How To Build A DIY Solar System
Designing and building a DIY off-grid solar system can be a cost-effective and sustainable way to generate your own electricity. Whether you’re living off-grid or simply want to reduce your dependence on the grid, a solar system can provide a reliable source of power. The process of designing and building a solar system can seem daunting, but with the right information, like understanding how to make your own DIY solar system, it’s totally doable.
Building a DIY solar system requires a fair amount of planning and preparation. The first step is to assess your energy needs by determining the total wattage of all the appliances and devices you want to run on the solar system and multiplying that number by the number of hours per day they will be used. Next, research the average sun hours per day in your area and the orientation and angle of your solar panels. This will be crucial in making your own solar system.
Once you have a better understanding of your energy needs and the amount of sunlight you can expect, you can begin to choose the type and size of solar panels, battery bank, DIY solar charge controller, and inverter that will be required for your system. Gather all the necessary components and materials, mount the solar panels in an optimal location, and connect all the components together. Once the battery, controller, and solar panels are all linked up, your DIY home solar will begin to take shape.
Also, it’s good to have a DIY solar monitoring system in place, so you can turn on the assembled system and test it while watching how it delivers voltage and current.
If you want to build your own solar system, you are in the right place! In this article, we will walk you through the process of assessing your energy needs, researching the average sun hours in your area, choosing the right components and materials, and assembling the system.
We will also go over some important considerations such as solar panel efficiency, types of solar panels, battery options, charge controllers, and inverters. As you embark on your DIY home solar journey, these elements will be key to your success.
How To Plan A DIY Solar System
Assess Your Energy Needs
Determining your power needs is the first step in building a DIY off-grid system or creating your own DIY home solar system. To determine your power needs, you need to calculate the total wattage of all the appliances and devices you want to run on the solar system. We also built a solar system and powerwall planner to help you figure out exactly what you need.
Make a list of all the appliances and devices you want to run on the solar system and note their wattage. You can find the wattage of each device by checking the label or the user manual. This will be crucial for making your own solar system.
Multiply the wattage of each device by the number of hours per day it will be used. This will give you the number of watt-hours (Wh) per day for each device. Add up the number of watt-hours per day for all devices to find the total number of watt-hours per day for the entire system.
To determine your power needs for your DIY solar system, you need to calculate the total wattage of all the appliances and devices you want to run on the solar system. This includes lighting, refrigeration, pumps, and any other electrical devices. You can find the wattage of each device by checking the label or the user manual. Once you have a total wattage, you can then calculate the amount of power you will need to generate daily to meet your needs.
For example, let’s say you want to run a refrigerator (150 watts), a laptop (50 watts), and a light bulb (60 watts) for 8 hours a day as part of your DIY home solar system.
Refrigerator: 150 watts x 8 hours = 1,200 watt-hours per dayLaptop: 50 watts x 8 hours = 400 watt-hours per dayLight bulb: 60 watts x 8 hours = 480 watt-hours per day
So in this example, the total power needed for the system is 2,080 watt-hours per day. This means that the solar panels, battery bank, solar charge controller, and other components you choose for your system need to be able to generate at least 2,080 watt-hours per day to meet your needs.
1,200 watt-hours 400 watt-hours 480 watt-hours = 2,080 watt-hours per day
It is important to note that this is an example and that you should use your own devices and hours of usage to determine your power needs when building your own solar system. Also, it’s important to consider that some appliances such as air conditioners, electric vehicles, and electric ovens tend to use a lot of power, and you should take this into account when determining your power needs for your DIY home solar system.
Select The Solar Panels
Based on your power needs for your DIY home solar system, you can calculate the number and size of solar panels required for your system. Solar panels come in a variety of sizes and power outputs, so it’s important to select panels that will generate enough power to meet your needs when building your own solar system.
Make sure to research the average sun hours per day in your area and the orientation and angle of your solar panels. Also, examine your property to determine what options you will have in terms of solar panel orientation and angle.
The orientation and angle of the solar panels also play a role in how much power they can generate. Solar panels that are positioned and angled towards the sun will generate more power than those that are not.
The more sun hours per day your area receives, and the better your solar panels are positioned, the more power your DIY solar system can generate.
Calculating the Size and Type of Solar Panels
There are several types of solar panels available on the market, each with its own unique characteristics and benefits. The main types of solar panels include:
- Monocrystalline solar panels: These are made from a single crystal of silicon and are the most efficient type of solar panel, with efficiencies ranging from 15-20%. They are also the most durable and have the longest lifespan. They have a distinctive dark color. These are a popular choice for a DIY home solar system.
- Polycrystalline solar panels: These are made from multiple crystals of silicon and are less efficient than monocrystalline panels, with efficiencies ranging from 12-16%. They are also less durable and have a shorter lifespan than monocrystalline panels. They have a bluish color. They are an affordable option for those making their own solar system.
- Thin-film solar panels: These are made from a thin layer of semiconductor material and are the least efficient type of solar panel, with efficiencies ranging from 7-12%. They are also the least durable and have the shortest lifespan. They have a variety of colors and can be flexible. While not as efficient, they can be a suitable option for specific DIY solar system installations.
DIY Solar System Efficiency
Solar panel efficiency is a measure of how well a solar panel converts the energy from the sun into usable electricity for your DIY home solar system. The efficiency of a solar panel is typically measured as a percentage and is determined by the amount of sunlight that is converted into electricity compared to the amount of sunlight that is received by the panel.
High-efficiency solar panels are able to convert more of the sunlight they receive into usable electricity, which means they can generate more power in a smaller area than lower-efficiency panels. This can be an important consideration when space is limited or when you want to minimize the number of panels you need to install. High-efficiency solar panels can be more expensive than lower-efficiency panels, but they can offset the cost over time by producing more power.
Low-efficiency solar panels, on the other hand, convert less of the sunlight they receive into usable electricity, which means they need more space to generate the same amount of power as a high-efficiency panel. This can be an important consideration when space is not limited, and you have a lot of areas to put the solar panels. Low-efficiency solar panels are less expensive than high-efficiency panels, but they may not produce as much power over time.
When choosing solar panels for a DIY solar array, it’s important to consider both the efficiency of the panels and the amount of space you have available. High-efficiency panels can be a good choice when space is limited, but they can also be more expensive. Low-efficiency panels can be a good choice when space is not limited, but they may not produce as much power over time. It’s important to keep in mind efficiency is based on the panels being clean, so always keep your solar panels clean for optimal performance when building your own solar system.
How Many Solar Panels Are Needed For A DIY Solar System?
Once you have considered these factors, you can use the following formula to calculate the number of solar panels you need:
Number of Panels = (Total Daily Power Needs (watt-hours) / Average Sun Hours per Day) / Panel Wattage
Choosing The Battery for your Solar System
The battery bank is used to store the energy collected by the solar panels. You need to select the type and number of batteries that will store the energy. Lead-acid batteries are the most common type used in off-grid solar systems, but lithium-ion batteries are becoming increasingly popular as well. We wrote up a full guide on building a DIY powerwall which goes into great detail on the power storage aspect of building a solar system.
Choosing the best battery for a DIY solar system is an important step in the planning process. The battery is responsible for storing the energy generated by the solar panels, so it is crucial to choose a battery that is suitable for your needs and budget. Here are some common cell chemistries and their characteristics that you can consider when choosing a battery:
Lithium Ion Batteries
These batteries are becoming increasingly popular in off-grid solar systems. They are lightweight, have a long lifespan, and require little maintenance. They come in different types such as:
- Lithium Ferrous Phosphate (LFP): These batteries are known for their safety, long lifespan, and low cost. They have a low energy density, which means they are not as efficient as other types of lithium-ion batteries.
- Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2 or NMC): These batteries have a higher energy density than LFP batteries, which means they are more efficient. They are also more expensive than LFP batteries.
- Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2 or NCA): These batteries have the highest energy density of all lithium-ion batteries, which makes them the most efficient. They are also the most expensive of all lithium-ion batteries.
- Longer lifespan: Li-ion batteries can last up to 10-15 years, whereas lead-acid batteries typically last around 5-7 years.
- Higher energy density: Li-ion batteries can store more energy in a smaller space, which makes them ideal for smaller systems or those with limited space.
- Lower maintenance: Li-ion batteries require less maintenance than lead-acid batteries and do not need to be regularly topped off with water.
- Higher efficiency: Li-ion batteries have a higher charge/discharge efficiency, which means they lose less energy during charging and discharging.
- Higher cost: Li-ion batteries are more expensive than lead-acid batteries.
- Requires specific charging/discharging cycles: Li-ion batteries require special charging and discharging cycles to maintain their optimal performance, which can make them more complex to operate and maintain.
Lead acid batteries are still the most common type of batteries used in off-grid solar systems. They are relatively inexpensive and have a long lifespan, but they do require maintenance. They come in different types such as:
- Flooded Lead-acid batteries: These are the most traditional type of lead-acid batteries. They are relatively inexpensive but require frequent maintenance, such as checking and refilling the water levels.
- Sealed Lead-Acid (SLA) batteries: These batteries are also known as maintenance-free batteries. They are sealed, which means they don’t require water refills. However, they are less efficient than flooded lead-acid batteries.
- Absorbed Glass Mat (AGM) batteries: These batteries are a type of SLA battery. They have a higher efficiency than traditional SLA batteries, but they are more expensive. They are also sealed, which means they don’t require water refills.
- Lower cost: Lead-acid batteries are less expensive than lithium-ion batteries.
- Widely available: Lead-acid batteries are widely available and easy to find, making them a good option for those who want to build their own solar system.
- Fewer special requirements: Lead-acid batteries do not require specific charging/discharging cycles, making them easier to operate and maintain.
- Shorter lifespan: Lead-acid batteries typically last around 5-7 years, whereas Li-ion batteries can last up to 10-15 years.
- Higher maintenance: Lead-acid batteries require regular maintenance, such as topping off with water, to maintain their optimal performance.
- Lower energy density: Lead-acid batteries can store less energy in a smaller space, which makes them less ideal for smaller systems or those with limited space.
- Lower efficiency: Lead-acid batteries have a lower charge/discharge efficiency, which means they lose more energy during charging and discharging.
LFP vs NMC For DIY Solar System
LFP batteries have a longer lifespan and are more stable, making them a good choice for long-term energy storage. They also have high thermal stability, making them less prone to overheating. However, LFP batteries have a lower energy density compared to NMC batteries, so they may be larger and heavier for the same amount of storage capacity.
On the other hand, NMC batteries have a higher energy density, which means they can store more energy in a smaller and lighter package. They also have a high power density, making them well-suited for high-power applications like grid-tie inverters. However, they have a shorter lifespan and are more prone to overheating compared to LFP batteries.
Ultimately, the best choice between LFP and NMC batteries will depend on your specific needs and the use case of your DIY solar system. If long-term energy storage is a priority, LFP batteries may be a better choice. If high-power applications and a smaller, lighter package is a priority, NMC batteries may be a better choice.
How To Choose A Battery Size For A DIY Solar System
When choosing a battery for a DIY solar array, you should consider factors such as cost, lifespan, efficiency, maintenance requirements, and weight. The overwhelming majority of the time, lead acid will have an initial lower cost but a larger total cost of ownership.
To calculate the size of a battery needed to power a home, you will first need to determine the total daily energy consumption of the home. This can be done by adding up the wattage of all appliances and devices that will be powered by the solar system and multiplying that number by the number of hours per day they will be used.
For example, if a home has the following appliances:
Refrigerator: 150 watts x 4 hours/day = 600 watt-hours/day
Lights: 50 watts x 4 hours/day = 200 watt-hours/day
TV: 100 watts x 4 hours/day = 400 watt-hours/day
Computer: 100 watts x 4 hours/day = 400 watt-hours/day
Total daily energy consumption = 600 200 400 400 = 1600 watt-hours/day
Next, you will need to determine the number of days of autonomy you want the battery to have. This is the number of days that the battery can power the home in case of no sunlight.
For example, if you want the battery to have 3 days of autonomy, you will need a battery that can store:
1600 watt-hours/day x 3 days = 4800 watt-hours
If the home’s daily energy consumption is 2000 watt-hours and you want the battery to have 4 days of autonomy then the required battery capacity would be:
For a home with a daily energy consumption of 10,000 watt-hours and a target autonomy of 3 days, a lithium-ion battery with a capacity of 30,000 watt-hours (10,000 x 3) would be needed.
For a home with a daily energy consumption of 15,000 watt-hours and a target autonomy of 2 days, a lithium-ion battery with a capacity of 30,000 watt-hours (15,000 x 2) would be needed.
For a home with a daily energy consumption of 20,000 watt-hours and a target autonomy of 5 days, a lithium-ion battery with a capacity of 100,000 watt-hours (20,000 x 5) would be needed.
Finally, you will need to determine the depth of discharge (DOD) of the battery. This is the percentage of the battery’s capacity that can be used before it needs to be recharged.
For example, if you want to use 80% of the battery’s capacity before recharging it, you will need a battery with a capacity of:
4800 watt-hours / 0.8 = 6000 watt-hours
Choose The Solar Charge Controller
A solar charge is responsible for regulating the flow of electricity from the solar panels to the battery bank. It ensures that the batteries are not overcharged or undercharged, which can damage the batteries and reduce their lifespan. There are two main types of solar charge controllers PWM and MPPT its important to consider both options.
When choosing a solar charge controller for a DIY solar array, you should consider the following factors:
Ensure that the charge controller is compatible with the voltage of your solar panels and battery bank. If the voltage is not compatible, the charge will not function correctly and could even cause a fire!
The most common voltages for DIY solar systems are 12V, 24V, and 48V. A 12V system is suitable for small, basic systems and is usually used for powering lights, small appliances, and charging devices.
A 24V system is more powerful and is suitable for powering larger appliances and devices. A 48V system is suitable for larger, more complex systems and is typically used for powering multiple appliances and devices at once. It’s important to note that the higher the voltage, the more efficient the system will be, but also the more expensive it may be.
It’s crucial to ensure that the charge controller is rated for the current output of your solar panels. If the current rating is too low, the charge controller may not be able to handle the amount of electricity being generated by the solar panels, which can cause damage to the system. If the current is too high, then you are wasting money if you don’t need the additional capacity.
It’s important to ensure that the charge controller is compatible with the type of battery you are using. Different battery chemistries require different charging voltages and methods, so it’s important to use the correct type of charge controller to ensure that the battery is being charged correctly and safely.
Some charge controllers include temperature compensation, which adjusts the charge voltage based on the temperature of the battery. This can help prolong the life of the battery by preventing overcharging or undercharging, which can occur at different temperatures.
Display and monitoring
Most charge controllers include a display that shows the voltage, current, and the state of charge of the battery. This can be helpful for monitoring the performance of the system, knowing when the battery is fully charged, and detecting any issues that may occur. It can help to ensure that the system is working efficiently.
The formula to find the right power level for your charge controller is:
Power level = Current rating of your solar panel x Voltage of your solar panel
For example, if you have a solar panel that has a current rating of 10 amps and a voltage of 12 volts, the power level of the charge controller you would need would be:
Power level = 10 amps x 12 volts = 120 watts
So the charge controller should technically be at least 120 watts, but it’s always best to over budget by about 20 percent so that you are not running your equipment at its limits.
Choosing DIY Solar System Inverter
An inverter is used to convert the DC power stored in the batteries to AC power that can be used to run appliances. There are different types of inverters, like a pure sine wave and modified sine wave, that you can choose from. When choosing an inverter for a DIY solar system, you should consider the following factors:
- Voltage: Make sure the inverter is compatible with the voltage of your battery bank.
- Current: Make sure the inverter is rated for the current output of your appliances and devices.
- Sine wave: There are two main types of inverters: pure sine wave and modified sine wave.
- Pure sine wave inverters produce a cleaner, more stable power output, which is better for sensitive electronic equipment such as medical devices, computers, and home theater systems. They are also more expensive than modified sine wave inverters.
- Modified sine wave inverters produce a less stable power output, and they are not recommended for sensitive electronic equipment, but they are less expensive than pure sine wave inverters. They are suitable for basic loads such as lights, fans, and refrigerators.
- Size: Based on your power needs, you need to select the size of the inverter. If you are planning to run several appliances, you will need a larger inverter than if you are only running a few devices.
- Efficiency: Efficiency refers to how well the inverter converts DC power to AC power. High-efficiency inverters will convert more DC power to AC power, which can save you money in the long run by reducing the amount of power you need to generate.
- Cost: Inverters can vary widely in price, so it’s important to choose an inverter that fits your budget while still meeting your needs.
Generally speaking, a pure sine wave inverter is always the best option unless cost is the most significant factor.
How To Build A DIY Solar System Step By Step
So, now that you know all the details, here is a step-by-step general overview of how to build a DIY solar system:
Step 1: Gather all the components and materials needed for the system.
It’s important to have all the necessary components and materials on hand, including solar panels, battery bank, charge controller, inverter, wiring, and mounting hardware to build your DIY solar system before you get started.
Step 2: Mount the solar panels on a suitable location that has good sunlight exposure, making sure to follow the manufacturer’s instructions.
Mounting the solar panels on a suitable location that has good sunlight exposure is crucial to ensure that your solar panels are receiving the maximum amount of sunlight possible. It is important to follow the manufacturer’s instructions when mounting the solar panels to ensure that they are installed correctly and safely.
Step 3: Connect the solar panels to the charge controller using the appropriate wiring. Using the right wiring to connect the solar panels to the charge controller is essential to ensure the most efficient and cost-effective operation of your DIY solar system.
Making these connections are simple. All you have to do is connect the positive output terminal of the solar panel to the positive input terminal of the charge controller. Then, connect the negative output terminal of the solar panel to the negative input terminal of the charge controller.
Step 4: Connect the battery bank to the charge controller. Make sure to use the correct type of battery and to follow the manufacturer’s instructions.
Connect the positive (red) cable from the charge controller to the positive terminal of the battery bank. Inspect the connection to ensure that it is securely attached to the terminal. Then, repeat that process for the negative (black) wire. Again, make sure that the cable is securely attached to the terminal.
Step 5: Connect the inverter to the battery bank. Connecting the inverter to the battery bank will allow your DIY solar system to power 120V AC appliances and devices.
This process will be the same as connecting the battery and solar panel, but with just a different input. So, simply attach the positive and negative connections to the load connection on the charge controller and you will be good to go.
Step 6: Turn on the inverter and test the system by turning on the appliances one by one. Check for any issues or problems.
Testing the system by turning on the appliances one by one is important to ensure that your solar system is working correctly. It is important to check for any issues or problems and make any necessary adjustments to the system.
Step 7: Make any necessary adjustments to the system, such as adjusting the angle of the solar panels or the charge voltage on the charge controller.
Making any necessary adjustments to the system, such as adjusting the angle of the solar panels or the charge voltage on the charge controller, is important to ensure that your solar system is working efficiently and effectively. It is important to periodically check the system and make any necessary adjustments to ensure that it is working at its optimal performance.
Step 8: Once the system is working properly, you can start using the power generated by the solar panels to run your appliances and devices. It is important to monitor the system and make any necessary adjustments to ensure that it continues to work efficiently and effectively. Additionally, it is important to maintain and service the system regularly to ensure that it continues to perform well and has a long lifespan.
How To Test A DIY Solar System
Once the system is assembled, you should test the system by turning on the appliances one by one and checking for any issues or problems. This will give you an idea of how well the system is working and if any adjustments need to be made:
Turn on the inverter: Start by turning on the inverter and making sure it is working properly. The inverter is responsible for converting the DC power stored in the batteries to AC power that can be used to run appliances.
Test the solar panels: Next, test the solar panels to ensure they are generating power. You can use a multimeter or a voltage meter to measure the voltage and current output of the solar panels. Make sure that the voltage and current output match the specifications of the solar panels.
Test the battery bank: Check the voltage and current of the battery bank to ensure they are within the recommended range. You can use a multimeter or a voltage meter to measure the voltage and current of the battery bank.
Test the charge controller: The charge controller regulates the flow of electricity from the solar panels to the battery bank. It ensures that the batteries are not overcharged or undercharged. Test the charge controller to make sure it is functioning properly by measuring the voltage and current of the battery bank while the solar panels are generating power.
Test the load: Finally, test the load by turning on the appliances one by one and monitoring the voltage and current of the battery bank. Make sure that the voltage and current remain within the recommended range when the appliances are turned on.
Finalize the testing by checking for any issues or problems. If everything is working properly, you can start using the power generated by the solar panels to run your appliances and devices.
Designing and building a DIY solar system is a great way to generate your own power, save money on your energy bills and be more self-sufficient. The process of building a DIY solar system begins with assessing your energy needs, then designing and implementing a DIY solar system.
To build a DIY solar system, you need to determine the total wattage of all the appliances and devices you want to run on the solar system, and multiply that number by the number of hours per day they will be used. Then. you will need to research the average sun hours per day in your area and the orientation and angle of your solar panels. This will help you determine how much power your solar panels can generate. After that, you can choose the type and size of solar panels, battery bank, charge controller, and inverter that will be required for your system. Once you have all the necessary components and materials, the next step is to mount the solar panels in an optimal location that has good sunlight exposure, making sure to follow the manufacturer’s instructions. After that, you will need to connect the solar panels
We hope this article provided everything you needed to know about how to build a DIY solar system, thanks for reading!
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How To Clean Solar Panels Dust, Dirt And Snow
When dust dirt and snow build up on your solar panels you can loose 5-25% of possible output. Check out our guide on how to clean solar panels to make this maintenance job quick, easy, and safe!
PWM Vs. MPPT Solar Charge Controller
If you are choosing a solar charge controller, some consideration is needed to decide whether MPPT or PWM charge controller is right for your application. We have laid out the two available options to help you make a clear and easy choice.
How To Connect Solar Panels To Battery
If you want to explore the realm of off-grid living, then you are going to need to know how to connect solar panels to a battery. Solar panels and batteries both come in a range of voltages and those voltages generally never match. So you need some sort of converter, regulator, or controller between the solar panel and battery.
Best DIY Solar Panel Kits – Pricing and Reviews
Solar panel kits can be used for a number of applications and are becoming more popular as the cost of solar panels has declined by more than 70% in the last decade. The most common use for solar kits are RV travelling, camping, boating and small off-grid cabins, as solar is a more attractive alternative to loud and smelly diesel generators or additional batteries.
These kits can also be used for a small building on your property that needs power, such as a barn or parking garage. Running electricity to these buildings can be expensive, particularly if all you need to power are a few light bulbs and small appliances. If you own a cabin that has a greater electricity demand and is off of the grid due to geographical reasons then a solar kit can be an excellent option.
There are also DIY solar kits for full-size homes (3kW – 5 kW) that have a larger electricity load (average residential solar size in the U.S. is approximately 6 kWs). These kits come with the same top of the line panels and inverters that you would get from a professional installer. People enjoy the thrill that comes from disconnecting from the grid or having back-up power. DIY solar can also generate energy savings depending on where you live and reduce the overall installation cost relative to a professional installation if you have the expertise to install the system.
Editor’s Summary Recommendation
Our recommendation is the Renogy 100 Watts 12 Volts Monocrystalline Solar Starter Kit. It features a highly efficient monocrystalline panel, is built in the USA and offers good value as a starter kit. Because it uses monocrystalline panels, it is lighter (19.8 lbs) and smaller dimensions that kits that use polycrystalline panels, which makes a difference for RV or boating applications. It can also be expanded up to 400Ws.
Best Solar Panel Kits Reviewed:
Solar Panel Kit ComparisonSolar Panel Kit Buyers GuideDetailed Solar Panel Kit Reviews
Renogy 100W 12v Solar Starter Kit WindyNation 100W Solar Panel Off-Grid Kit Grape Solar 100W Basic Off Grid Solar Kit Renogy 400W 12V Solar Starter Kit Grape Solar 400W Off-Grid Solar Kit
Solar Panel Kits Comparison Table
|Renogy 100W 12v Solar Starter Kit||Mono||Renogy||100W||Off Grid|
|WindyNation 100W Solar Panel Off-Grid Kit||Mono||WindyNation||100W||Off Grid|
|Grape Solar 100W Basic Off Grid Solar Kit||Poly||Grape Solar||100W||Off Grid|
|Renogy 400W 12V Solar Starter Kit||Mono||Renogy||400W||Off Grid|
|Grape Solar 400W Off-Grid Solar Kit||Poly||Grape Solar||400W||Off Grid|
Solar Panel Kits Buyers Guide
Buying the right solar kit for your specific application is important if you are going to extract the most value and usefulness from your purchase. Some important things to consider are:
The key items in a solar kit are solar panels, a charge controller, a battery, and an inverter. Some solar kits will include a few of these items, leaving you to buy the other components separately. Here is a simple diagram that explains how the solar system relates to each component, and what they each do. Note that the solar kits in this review do not include batteries and we have included advice on several battery options in the Buyers Guide.
The second most popular solution is to have a battery installation that gets charged during the sunny hours, and then when it gets dark you can switch to an inverter which changes your stored DC voltage into AC voltage for your appliances. Most solar reliant houses will have DC LED lighting to make the most of the lower power consumption of these efficient lighting products.
Working out your energy requirements is important before you go out and buy your next solar kit. Simply follow our guide and to calculate how many solar panels and batteries you will need based on your appliances and lighting. This is a very simple formula, but will require a bit of input from you.
Step 2: Calculate your solar panel requirements. Assume you will receive 4 hours of full sunlight per day ( check the DOE for exact amounts in your zip code), so a 100W panel will generate 400Whs of electricity (100W x 4 hours). Take your daily electricity usage (1,475 Whs) and then divide that by 400Whs per panel = ~3.7 100W panels or 4 with some cushion.
Step 3: Estimate your battery capacity. We need to factor in bad weather, so we will multiply your daily electricity usage by 2 days as a safety measure in case we don’t have enough sun to charge our batteries. Because we don’t ever want our batteries to discharge below 50%, we will then multiply this number by 2. So your daily electricity usage is 1,475 x 2 days x 2 (50% capacity) = 5,900Whs.
Step 4: Next we need to work out our total amp hours that we will need for our battery installation. We do this by dividing our total daily watt-hours by our battery voltage which is 12v in this case.
Example – 5,900Whs / 12v = 491AH
Step 4: Check your battery’s amp hour rating and then divide the total amp hours by your battery’s amp hour rating. Our example batteries have 105AH per battery
Example – 491AH / 105AH = 4.7 batteries (or 5 to round up for cushion).
These calculators may also be helpful.
Batteries are an important part of your solar kit installation if you plan on using your stored solar power when the sun goes down. Most solar kits don’t come with batteries, so you will have to choose the best battery for your needs. Luckily you can use the above formula to work out exactly what you need to keep your system powered up when you need it the most, at night.
Here are some of the better options for your solar battery requirements:
We understand that not everyone is familiar with of the terms and concepts that are used frequently when it comes to solar technologies, so we have included a simple glossary to explain some of the more common terms that you will come across when installing your solar kit.
Voltage – The force of electricity as it moves, measured in volts
Watts – This is an energy rating that we get when multiplying volts by amps
Amps – This is a unit of current, or a rate of flow. One volt across one ohm of resistance is equal to one amp.
Polycrystalline – This is a type of silicon wafer that is used in the construction of solar panels. It is made from many different crystals and is slightly less efficient than Monocrystalline panels.
Monocrystalline – This is a silicon wafer with a single crystal and is slightly more efficient than Polycrystalline panels.
Amp Hours – This measures a battery’s energy capacity and measures the flow of current per hour
Solar Panel – This is a flat panel that absorbs light and produces electricity
Solar Cells – Multiple solar cells make up a single solar panel and there are many inside a solar panel
Larger System Options
|3kW Ground Mount Kit||1.89||SolarEdge||3kW||Ground Mount|
|3kW Roof Kit||1.53||SolarEdge||3kW||Rooftop|
|5kW Ground Mount Kit||1.89||SolarEdge||5kW||Ground Mount|
|5kW Roof Kit||1.53||SolarEdge||5kW||Rooftop|
Solar Panel Kit Detailed Reviews
Renogy 100W 12v Solar Starter Kit
This is a well-built solar kit from Renogy, and it is capable in many different scenarios, from being installed on top of an RV or trailer, to being installed as part of a larger solar array, the Renogy 100 watt Solar Starter Kit is a solid choice. The panel is made from monocrystalline, which is a more efficient material than polycrystalline (smaller and lighter). This is because the yield of silicone is greater and of a more pure consistency on the mono panels as opposed to the poly panels. The kit comes with a charge controller, called the Renogy Wanderer, meaning that you can expand your installation up to 400w, or 4 panels at a later stage when you decide to increase your solar capacity. Some consumers have complained about the quality of the controller, but the company has recently upgraded the controller – the Wander is a good value and works for most people.
Renogy was started by students at Louisiana State University, is listed on the Inc. 5,000 List and is based out of Ontario, California
DIY Off-Grid Solar Power System for Homestead. Installation Wiring Guide
If you’re looking for a safe, reliable way to build your own massive DIY off-grid solar system at a fraction of the cost, you’ve come to the right place.
Hi there, we’re Jonathan Ashley from Tiny Shiny Home. Our family of 6 spent many years traveling full-time in our renovated vintage Airstream before finding some off-grid property in Cochise County, Arizona to settle on.
Our dream here is to build a sustainable off-grid homestead from the ground up using solar power, water catchment, and natural building techniques to create an oasis in the desert.
If you’re looking for a safe, reliable way to build your own massive DIY off-grid solar system at a fraction of the cost, you’ve come to the right place.
We’ll be doing a full cost breakdown in a separate article and video, but today we’re focusing on the planning, building, and installation process we went through to build a fully independent off-grid power system.
Before we go further, let’s give you a high level overview of our off-grid solar power system.
- 7,200 Watts of Solar Panels (5S6P)
- 28kWH of Lithium or LiFePO4 Batteries (2P16S @ 48 Volts)
- 5,000 Watt Inverter (Single Phase @ 120V, Surge to 10,000W)
- This should power our Airstream, Solar Shed, and eventually our House
Disclaimer: I’m not an electrician, nor do I play one on YouTube. All information here is solely for entertainment purposes, and all electrical work should be performed by qualified individuals according to local electrical codes. Cool? Cool.
Off-Grid Homestead Solar Wiring Guide
Ever wondered what all the major connections look like on a custom solar system like ours? As part of this deep dive, we created a very detailed replica of our wiring setup.
I know I’m a visual person, and sometimes I just need to see it all laid out no matter how many words there are to explain it.
This is as big as I can make it here on the site. if you’d like to download a vector PDF that you can zoom in on, grab a copy here:
Download Our Solar Wiring Diagram
Get up close and personal with this super detailed, impeccably illustrated hi-res PDF of our full off-grid power setup with a schematic representation of how everything in our 7200W, 28kWH, 120V off-grid battery and solar system connects together. Includes bonus individual component wiring configs, too!
- Housing the System: Earthbag Solar Shed
- Off-Grid Power Goals
- Sizing an Off-Grid Solar Power System
- Finding the Right Solar Panels
- Solar Ground Mount
- Wiring the Solar Panels
- Finding the Best Lithium Battery Deal
- LiFePO4 Shipping Update
- Assembling the LiFePO4 Battery Pack
- Major Fuses, Disconnects, and Breakers
- REC BMS Install
- Victron Color Control GX VRM Portal
- Victron Quattro 48V 5,000W Inverter
- Victron SmartSolar MPPT Solar Charge Controllers
- Final Tweaks Adjustments
- Real World Impressions Power Usage
- What Would We Do Differently?
- Lightning Protection
- Cost Breakdown
- Wrapping Up
Housing the System: Recap of our Earthbag Solar Shed Project
We have to mention that our solar and electrical install were part of a larger project. our hyperadobe earthbag solar shed office. Besides needing somewhere to store our batteries and power gear, we needed an office, a guest room, and really just some extra breathing room. The Airstream was getting a little cramped.
Plus, it was a chance to explore a bunch of natural building techniques that we’ll use as we design and build other earthbag buildings here on our property. Setting up an independent power system was an important piece of infrastructure, a huge step for our homestead.
We’re excited to share our power setup with you because we believe we’ve found an incredibly cost effective way to build a massive 100% off-the-grid system that is safe, stable, and reliable.
Off-Grid Power Goals
Let’s start by talking quickly about our situation. While our property was completely off-grid, connecting to the the power company wasn’t out of the question. We can see our closest power pole about half a mile up the road, so theoretically it could’ve be possible to run those lines to us.
Like we mentioned, running off grid power wasn’t really part of our dreams or goals. but turns out it’s really expensive to run a power line half a mile. Like 35,000! And then we’d get the pleasure of paying the power company every month for our usage.
So not only did our resolve to stay off-grid send us down the road of building our own system. it turned out we could build the whole thing cheaper than it would’ve cost to run the power to our property anyway.
We knew this off-grid solar system needed to be large enough to power our Airstream, Solar Shed, and eventually our house. And we also knew that a 48V lithium battery bank was the way to go. Inverting from 48V to 120V is so much more efficient than 12V or 24V, but still low voltage enough to work with safely.
This setup needed to power some large appliances. air conditioners, power tools, transfer pumps, and kitchen gadgets like a blender and instant pot.
But we also wanted to be Smart about our usage, especially in the cold months. For heating and cooking we would supplement as much as we could with propane, gas, or wood. And by building with earthbags we took advantage of thermal mass transfer and passive solar heating.
This meant we could setup our power system at 120V power instead of 220V. Our stove would be gas or wood, and a we really don’t need a clothes dryer out here with our endless sun and low humidity. Should we get in a situation where we need 220V power, we can always switch out the inverter or add more batteries.
Sizing an Off-Grid Solar Power System
Let’s talk big picture setup before we get super nerdy. Based on our goals out here, and the fact that we’d been living low power in our Airstream for years, we already had a pretty good idea of how much power we’d need. But we reached out to Juan from Beginning From This Morning to help us work through the transition from a 12V system to a 48V system. After a few conversations we decided on a few specs:
7,200 Watts of Solar Power
By connecting 240w panels in series of 5, we could create high voltage arrays that charged well even in cloudy conditions. This also helped keep our wire size down as we had a fairly long run from the ground mount to the charge controllers (over 100’). We ended up with 30 panels total for this project.
28kWH Lithium Battery Bank
Battery bank size is always tricky. trying to find the right balance between having enough storage and not spending too much money. Fortunately we found some great deals on 280AH cells shipped directly from China, and were able to create a large bank for an incredible price. We knew the BMS would only have 16 cell inputs so we opted for 32 total batteries, grouping them in packs of 2. We’ll get into this more later.
5,000 Watt 120V Power Inverter
Finally, the inverter. Again, lots of options here for massive wattage, but we settled on a 5,000 Watt Quattro Inverter Charger from Victron. It surges to 10,000 watts which should be more than enough for us. And if we ever need more power we can daisy chain these units together. The decision to go with Victron also tied into our charge controllers, BMS, the ability to monitor the system remotely, and manage all power systems on the property from one app. Also more on this later.
Finding the Right Solar Panels
As you can imagine, there are a plethora of options out there for residential and commercial solar panels. When renovating our Airstream, the size and weight of the panels on the roof were a huge consideration. But here on our 11 acres of property we could install as many panels as we wanted. The sky was the limit! Well, really our budget was the limit.
And we wanted to get the most bang for our buck. So we did a ton of research and ran across SanTan Solar. They’re a (semi) local solar panel dealer that specializes in both new and refurbished used panels of all kinds.
Here’s a secret. solar panels get replaced often. usually way before they need to be. So SanTan buys them, tests them extensively, and resells them to folks like you and me at a fraction of the cost of new ones.
They still have plenty of life left in them, and the cost savings can be so significant that even if they need to be replaced a few years earlier you’re still getting a great deal.
During their yearly Sidewalk Sale, we snagged all 30 of our 240W solar panels for only 25 each. That’s a crazy deal. 7200W of solar for less than 800. Whoah!
As you’ll see below, we still had to build a massive ground mount to attach these to, but we were off to a good start saving some cash.
Solar Ground Mount
Now before we could install any of our gear, we needed the solar panels mounted and ready to use. That in itself was a massive project. Since we didn’t have a roof to mount on. and because the solar shed itself was setup for passive solar, and the roof was tilted North. we had to create a solar ground mount array ourselves.
Thanks to some simple online tools we calculated our panels needed to be tilted about 30 degrees and pointed about 10 degrees East of South.
Fun fact. here in the high desert of South East Arizona we have weather events that can create up to 100mph updrafts. And our soil is high in sand content. So engineering what’s effectively a huge windsail of solar panels wasn’t as simple as throwing them on some wooden posts.
Thankfully there are a few companies out there that will help you do this. We used IronRidge’s Design Assistant Tool, to design a heavy duty ground mount, and were impressed with its level of detail. They help you work through:
- Foundation type
- Titling angle
- Snow loads
- Wind events
- Soil type
- Panel configuration
- And more.
They even let you use custom panel dimensions which is perfect because we bought used residential panels from SanTan Solar.
Then they output technical drawings with easy to read dimensions and all sorts of other complicated data like shear and uplift strength, the total amount of pipe and cement you’ll need, and more.
Now of course, IronRidge is selling you something. they make quite a few of the important pieces you’ll need to build your mounting system. the reason they do this is to give you an estimate for what you’ll need to buy from them.
But without this tool we would have spent days trying to calculate all this stuff, and would have had no idea where to start. Let’s start with the basics.
Note: none of the IronRidge components here are affiliate purchase links because the cost per piece on Amazon is insane. Build your setup with the Design Assistant Tool, and it will give you a full parts list, and then help connect you with a local distributor to get the best pricing.
Assembling the Ground Mount Frame
The frame of your solar ground mount will be 2” or 3” Schedule 40 Steel Pipe. We went for the 3” due to the size of our mount. You can either concrete your piers into the ground or use massive ground screws depending on your environmental conditions. In our case, the soil was too sandy so concrete it was. IronRidge doesn’t sell the pipe so we had to source from a local metal yard. This was during COVID so were higher than usual.
We also ordered a few pallets of concrete, cinder blocks, and jacks to help us build the frame. on that in a minute.
Using the diagrams generated by IronRidge, we planned and marked the 8 pier holes needed for the mount. Then our friend came out with his tractor to auger the 12” wide 7’ deep holes they required for installation.
But it turned out that with the extension, his tractor arm couldn’t go high enough to start drilling. So we adjusted the settings for 24” holes instead which got us to about 5.5’. The downside was that this created the need for a lot more cement. It also meant we had to rent a different auger.
But we didn’t want to skimp on the strength of the structure so we called Lowe’s and had a few more pallets of cement delivered, and waited till the next weekend to use the 48” auger.
Then we had to cut the steel pipe. It came in 20’ lengths which meant our 32’ long array had to be built in multiple pieces. Also, we had to cut the piers to certain lengths depending on whether they went in the front or back. There was lots of measuring and re-measuring to make sure we did this right. We only had one shot at cutting. For the long pieces we had to make sure that they were cut to hit right on top of a pier for stability.
Again, the IronRidge Design Assistant Tool, was super useful in helping us know exactly how long to cut each piece.
Once the holes were dug, it was time to use stacks of cinder blocks and jacks to get the horizontal rails in place both parallel with each other and leveled horizontally. As you can imagine, lining all this up took a while, and we had to re-adjust many times.
But we finally got it! This meant our main horizontal supports were exactly where they needed to be. So it was just a matter of attaching the vertical piers via IronRidge’s Top Caps, letting them hang in the holes, and filling with cement.
I say just. we’re talking over 200 bags of Quickcrete here. It took DAYS to mix by hand and fill in. I never wanted to see a bag of concrete again.
Installing Solar Panels
With the frame in place, it was time to install the other IronRidge pieces. Their rails are the centerpiece of the system. we went with the XR1000 which is rated for heavy loads and high winds. Since our panels were 6 across and 5 down, we needed 12 rails (one on each side of each array). Here’s a visual.
These rails are held on by Rail Connectors. an L shaped piece of steel with U Brackets to attach to your pipe. You have to do some measuring to set them in the right place, but once you get going it’s pretty easy.
And pretty forgiving, too. The more we worked with this system we realized that much of our stressing about everything being perfectly lined up wasn’t necessary. The whole thing is designed with a lot of wiggle room.
Once your first two rails are in you can start installing solar panels! Panels are mounted to the rails using UFO’s or Universal Fit Objects. They have a small foot that slides down the track on top of the rails and then clamps down on top of the panels.
On the first and last panel of the vertical array you have to attach Stopper Sleeves to the UFO’s. This provides a solid, flat surface for the panels to sit against.
Set your first panel on the UFO’s then slide two more in the track so they touch the top of the panel. Slide the next panel down on those UFO’s and repeat.
You also need to tighten down the UFO’s to the correct torque. Too much and you could break the panel. Not enough and it might fly away in a wind storm.
Speaking or torque, there are several parts of this process that require exacting torquing specs. I recommend getting both foot pound and inch pound torque wrench’s as well as a deep socket set.
Wiring the Solar Panels
With the ground mount built, and the panels attached, we turned our attention to wiring. Like we mentioned, our plan was to group 5 panels at a time in series to run at high voltage. This meant the panels would produce more power earlier and later in the day or in cloudy conditions, and that the amps being transferred to the batteries would be lower, allowing us to use smaller wire for the conduit runs. Remember our mount was over 100’ from the solar shed, so cost was an important consideration.
Here’s how the math worked out. Each 240W solar panel array connected 5 in series produced 1200 Watts, 186 Volts, 8 Amps. Then connecting all 6 arrays in parallel created a 7200W, 186V, 50A solar panel system.
Grouping the panels 5 in series meant we had 6 total arrays (or 5S6P). It also meant that we had to create a bunch of solar wires to complete the series back to the combiner boxes. That meant buying our own MC4 connectors and hundreds of feet of PV solar wiring. And again, lots of measuring. One end of the series was always closer than the other, and each array got farther from the combiner boxes. So for our size panels we needed 300’ of 10 AWG PV Wire and 24 MC4 Connectors.
Finding the right combiner box(es) was important. They needed to be the right size in terms of voltage and amperage for each array, and because of our wide open skies a lightning arrestor was necessary to protect the gear inside the solar shed from a lightning event. We ended up with these Eco-Worthy combiner boxes. They’re heavy duty, rain proof, and already have MC4 connectors installed to make connections easy.
Even though they sell a 6 string, we decided to buy two 4 string boxes just in case we ever wanted to expand and add more panels later. So one combiner box has 4 strings and the other has 2.
Honestly, figuring out a way to mount the combiner boxes to the 3” pipe was more complicated than hooking the wires up. But with some pipe clamps, plywood, and Unistrut we figured it out.
Once the panels were connected, we started our trenching conduit runs.
I won’t go into a ton of detail here as your trenching requirements are likely very different than ours. But there are a few important things to keep in mind.
The first is that the length of the run out of the combiner boxes, and the amount of amps running through these wires is important. For us, we decided to go with 6 AWG wire for the 100ft run because each combiner box had a potential of 32A. It’s cost effective, but also still oversized in case we want to add higher capacity panels later (more on this below).
Note: the link above it to Amazon, but you can likely source this much cheaper at your local hardware or electrical store.
The second is that you’ll want conduit large enough to easily pull your wires through, keeping in mind any twists and turns along the way. We went with 1.5” electrical conduit for our four 6 AWG wires. And we had 6 90 degree bell turns. Fish tape helped a ton with this process. We bundled them together and pulled them all at the same time.
Our local codes call for electrical conduit it to be buried at least 2’ so we dug a trench by hand, glued everything together, and pulled the wires through into the solar shed. One day we’ll get a tractor or ditch witch, because that was way too much work!
The final piece for the solar mount was grounding. The IronRidge system is designed so that all the metal frames of your panels are connected together, meaning you just have to run a copper line to a copper ground rod off one of the rails. They supply the lug connection for you. In our case, we decided to add a second ground rod to connect to the lightning arresters in the combiner boxes as well. Then we ran another copper wire between the two.
This should allow the lightning arresters to trip if lightning were to ever hit the mount or anywhere near it. Out here indirect lightning strikes are totally a thing, so just trying to be extra careful. When it trips, it cuts all power from the combiner box so no surges can make it into the shed and destroy the charge controllers, inverter, batteries, etc…
Finding the Best Lithium Battery Deal
There are so many ways now to build a large battery bank for off-grid living. But the one constant is that you should definitely be looking at Lithium Ion or LiFePO4 batteries.
Lead acid or AGM batteries are bigger, heavier, wear out quicker, can only use half the capacity, charge slowly, and are affected by large loads.
But Lithium batteries are smaller, lighter, last much longer, use most of their stated capacity, don’t have much voltage sag, and charge quickly.
For reference, the batteries we purchased have a lifespan of 2,000 to 3,000 cycles. Currently we’re using about 10 cycles per month because we have so much solar, and the State of Charge rarely drops below 80% overnight. That means these batteries could easy last anywhere from 15-20 years if we take care of them. Whoah!
The one downside is that Lithiums are more expensive and need a brain or BMS to manage the cells. But if you are building an off-grid system to use full time, the investment in lithium pays off easily.
These have been the main options on the market so far:
- Tesla sells the Powerwall which includes a battery pack, inverter, and charger all-in-one.
- Used electric car batteries are very popular as well, Chevy Volt and Nissan Leaf being the most widely used.
- Rack Mounted 48V Systems like the LifePower4 EG4
- And of course everyone’s getting into the lithium cell game with companies like Battle Born that have a BMS built into each battery.
There are some issues with these, though:
- Powerwalls are crazy expensive per kWh (500/kWh).
- Battle Born’s are also ridiculously expensive (720/kWh), and the built-in BMS doesn’t interface well if you have more than one.
- Rack mounted systems are a little cheaper (300/kWh).
- Electric car batteries are all over the map (170-300/kWh), but they’re difficult to source, and then they often come in a hard to open housing with lots of voltage and setup quirks.
What if you could buy small, efficient, easy to connect cells that allow you to build your own bank exactly how you want at a fraction of the price?
Enter Alibaba. Here’s the thing. Other than Tesla, all those lithium cells I mentioned above come from China anyway. In fact, just about every other lithium battery you buy. whether it comes in your phone, laptop or a flashlight. come from China. They know how to make lithium batteries.
And recently there’s been a surge in competition for these cells. Do a search on their site and you’ll get thousands of results for 3.2V 280Ah lithium Grade A cells.
We paid about 130/kWh in the middle of COVID for our batteries, so there’s a chance they’ll be even cheaper in the future. With these insane we got estimates from a few suppliers and bought 28kWh or 32 battery cells directly from China for only 3,700.
The Tesla or Battle born options would have cost 5-7x more for the same amount of storage. The trick is you have to assemble yourself. We’ll get to that in a minute.
Beware the Purchasing Process on Alibaba
Before I get too ecstatic about these cells, we have to talk about the buying experience on Alibaba. In a word: “sketch city.” Things started out ok. The conversations I had with each supplier were super helpful. They all were asking important questions like, “What are you going to do with all these batteries?”, and “How are you connecting, what voltage, what size bank are you looking for?” to make sure my math was correct.
I picked a supplier, and accepted the offer. The trouble started when I went to pay. My Apple Card was immediately declined. Then apparently because I had a credit card declined I was not ever allowed to pay with credit cards again. Western Union was an option. I mean, c’mon. how much more sketchy can we get? I was about to give up, but decided to try Paypal and it actually went through! Sweet!
But wait! The saga isn’t over yet. Literally the day after I paid I got a message from the supplier saying the cells I ordered weren’t available anymore along with a bunch of spec sheets in Chinese for a similar cell that they would send instead “at no extra charge.” We went back and forth over this for several days. the new cells were REPT instead of EVE. This may not mean a lot, but if you do any research on these cells, there’s a lot more real world experience with the EVE cells, and they come highly recommended. I was hesitant to accept this change because there wasn’t much data about REPT yet.
I told them I’d prefer what I paid for, but they said it would be another 6 months before they got them in. With COVID and all sorts of shortages going on I decided to take the risk and settle for REPT. Why? Because they get shipped via freight overseas and it takes months to receive them. And we needed them ASAP.
I kind of feel like this whole process was more of a cultural thing. In the US when you buy something you expect to get exactly what you ordered. But the Chinese supplier really wanted to sort of wheel and deal, and change things up afterwards. this was really foreign to me and made me uncomfortable.
After agreeing to the new cells, it was a matter of waiting. And man, did we wait. The FedEx tracking numbers they gave me never showed any updates. I messaged them several times for some kind of tracking info, and they sent over shipping manifests completely in Chinese.
I was starting to get worried I got ripped off. Finally they said the ship was at port, but because of the pandemic was just sitting out there, and it hadn’t been unloaded. Then a few weeks later it was in customs with no timeframe for release.
And then, 2 1/2 months later the FedEx guy showed up with 8 big heavy boxes of batteries! And that FedEx tracking number still never showed any updates.
Now here’s one thing you should know. The way Alibaba works is that they function as a middle man. So we paid them, and they hold the funds in Escrow until we receive and sign off. Then they release the funds to the supplier. So theoretically we were somewhat protected the entire time, it just felt sketchy.
Also, several other YouTubers have had mixed success actually receiving Grade A cells that aren’t prone to swelling and capacity loss (they likely received Grade B or C cells).
- Going through Alibaba instead of Aliexpress
- Sticking to well known cell names like EVE or REPT
- Getting quotes from multiple suppliers, and avoiding any that seem too good to be true. Even with our amazing cost savings here, an even lower price can be a red flag.
- If you’re curious, we bought our cells from Dongguan Lightning New Energy Technology Co
- This is the exact listing: 3.2V LiFePO4 REPT 280Ah
That being said, our batteries were all packaged very securely, with no swelling, in perfect condition, and almost perfectly top balanced with each other right out of the gate. So if you do your diligence and don’t mind dealing with a bit of sketchiness, you can assemble yourself a large lithium battery bank at a fraction of the cost of other options.
LiFePO4 Shipping Update
Since writing this article, I got an email from the same supplier I bought my batteries from, and they had a very interesting piece of information. Apparently they’ve seen the long wait pain point and have setup a warehouse here in the US with a stockpile of EVE, REPT, and CATL grade A lithium batteries that are ready to ship without all the overseas customs and wait times.
In fact, they told me it would only take 3-7 days to receive the cells here in the U.S. That’s a huge deal! And after looking at the current battery for the cells I bought vs these stateside stockpiled cells there’s barely any difference in cost. just a few bucks per piece.
And these are “DDP” or Delivery Duty Paid which means the price they give you includes import duties, customs and any clearance taxes. Even better, their sales rep Hayley told me that if you mention Tiny Shiny Home they’ll give you an extra discount.
Use these non-affiliate links to buy them directly:
Now let’s get into how we built our battery bank.
Assembling the Lithium Battery Bank
While using these types of cells made the process of building our battery easier, that’s not to say it was a simple process. There’s so much to keep in mind.
Series vs. Parallel
The first is how do you connect them? Batteries wired in series means their voltages are added together. But batteries wired in parallel will have their amp-hours added together.
We knew we wanted a 48V system, and we also knew that the REC BMS we were going to use had 16 cell inputs.
So in our case, it was just a matter of doing the math. We could have bought 16 of the 3.2 V battery cells, connected them all in series, and created a 48V system (3.2v x 16 = 51.2V). But that would have only been about 14kWh of storage (280AH x 50V = 14kWh). Don’t get me wrong, that’s a lot of storage, but we wanted a larger bank for our needs.
The simplest way to add more size to the bank was just to double it. So we bought 32 cells, grouped them in packs of 2 via a parallel connection, and then joined each pack in series. So the first bit of math stayed the same (3.2v x 16 = 51.2V), but the storage capacity doubled (280AH x 2 = 560AH), (560AH x 50V = 28kWh).
As for the actual connections, the batteries shipped with threaded posts, bus bars and nuts. Some folks don’t like threaded posts because you can strip them out easily if not put in correctly. we didn’t have any issues, though. Also, the bus bars they came with were thin, and honestly there just weren’t enough of them. So we decided to buy 16′ of 1/8” x 1.5” copper bar stock, and cut it, drill it, and make our own.
Before we could connect, though, we had to build a battery box. The first step was to decide how they would be organized. The best way would be all 32 end to end, flipping each pack of 2 for the series connection, but we didn’t have room in our tiny solar shed for that. So we planned on two rows of 16, stacked on top of each other.
Lithium batteries need to be compressed so they don’t swell over time, so we got some heavy duty plywood, cut to slightly larger the size of a battery, stacked them end to end, and used allthread rod and nuts and washers to create a compression frame for each row of 16.
Then we welded a metal frame that would hold the weight of each row. Each cell weight about 11.5lbs, so each row was 184lbs. Huge thanks here to Juan and Michelle from Beginning From This Morning for helping us not only plan the battery setup, but the frame itself. A ton of thought went into making it.
With our packs created, we slid them into the frame, and began to connect the bus bars. They were carefully measured, cut, and drilled so they slid down over the threaded posts so that 2 cells were connected in parallel and then each pack of 2 was connected in series. I know that sounds confusing, but this is what it looks like:
Then all we needed to do was connect the negative of the top row to the positive of the bottom row to continue the series connection. We used 2/0 welding cable for this and crimped our own lugs on.
Before we tightened the nuts down to hold everything in place, we needed to add the cell connections for the BMS. We’ll cover the BMS in more detail below, but for now just know that in order for the BMS to keep the cells balanced, it needs a wire connected to each cell’s positive terminal. This used small 18 AWG wire with ring terminals crimped on to the positive terminal for each group of 2 cells.
Finally, we needed to run heavy duty 2/0 welding cable off the first positive terminal and last negative terminal to the system posts. We’ll get into more detail for that below as well.
Protecting the System: Major Fuses, Disconnects, and Breakers
Before we get into wiring the BMS, let’s talk about the main sources of protection in the system. The first is a T-Class Fuse. The idea behind the T-Class Fuse is that during an unwanted power surge event, it will blow break the main connection to protect your equipment. You’ll create a 2/0 AWG wire and crimp on lug that runs from the positive post of the battery to one side of the fuse block. This should be as physically close as possible to the batteries.
On the other side of the fuse, you’ll create another 2/0 wire that goes through a large switch or disconnect. This will allow you to turn off battery power to the other electronics, and shut the system down to do maintenance.
After that you’ll continue using 2/0 AWG welding cable cut to size with crimp lugs to connect to one side of the contactor, which is tied to the BMS. The other side will flow through a 200A Double Pole toggle or breaker and then is wired directly to the Inverter. The 200A breaker also protects the system in the event that the Inverter has a power surge.
The BMS uses the contactor to turn your system off if it detects under/over voltage or high/low temps. the system side is only activated if the BMS says everything is ok. Otherwise it breaks the connection.
The last major connection in this loop is a large 2/0 welding cable that goes from the negative input on the Inverter to the negative side of your Current Sensing Shunt (see below).
One important safety note: As you install any breaker or switch, always make sure it’s in the “off” position, and leave it that way until you start to boot up the system.
REC BMS Install
I can’t overstate enough how important a BMS or Battery Management System is for a large battery bank like this. You HAVE to protect these cells from over charging, under voltage, and temperature extremes. And if you want them to last for years and be a good return on your investment, the BMS needs to be able to balance the cells and keep them all close to the same voltage.
Like I mentioned, Lithium batteries are amazing, but need a BMS for these reasons:
- Over Voltage: overcharging the batteries can be very dangerous and cause swelling or fires. The BMS constantly checks for high voltage and shuts off the system if needed
- Under Voltage: batteries that have discharged too low can also be permanently damaged if tried to use during that state. The BMS checks for low voltage and will shut off the system until it reaches a safe threshold.
- High Temperatures: the stability of lithium battery cells depends on keeping them within their operating temperatures. If you’re charging them while they’re too hot, this could lead to a fire.
- Low Temperatures: lithium batteries will be damaged if you try to charge them and their internal temperature is below 32 degrees. So the BMS checks for cell temperature and shuts down the charging aspect if needed.
- Charge, Float, and Hysteresis: a good BMS will let you set these parameters so that over voltage and temperature issues never happen in the first place. The BMS should talk to your charge controller and help it fill and float the system safely.
- Balancing Cells: There are a number of reasons your cells voltages may not sync up at the same time. and keeping all your cells near the same voltages will drastically increase their life. A good BMS should be able to equalize or balance all the cells’ voltages by diverting some current from higher voltage cells to the whole pack or from the whole pack to a lower voltage cell.
Trying to run a large off-grid lithium battery bank without a BMS is asking for long term issues, reduced battery life and return on investment, and even worse explosions or fire. Spend the extra cash and get yourself a proper BMS.
We chose REC BMS for a few reasons.
- They have a great reputation for stability and customization, and are particularly knowledgable of using batteries off-grid.
- Their support is fantastic, and very technically detailed
- Their products can talk natively to Victron gear using the proprietary Victron VE.Can protocol. This was important for setting both charge controllers and the Color Control GX which is the heart of our monitoring system.
- Deep level settings are accessible via their new Wi-Fi Module so you don’t have to connect a computer to make updates
- Measures battery temperatures via probes, but also has an internal temperature for the unit itself (we’ll talk about why this is important later)
- Displays real time info at the cell level on it’s own touch screen
- Can be configured with a Precharge Delay. This should prolong the life of our equipment by sending a trickle charge to components so that they don’t get hit with a large in-rush of current.
- Measures current using a precision shunt resistor. this gives a very accurate “State of Charge” percentage.
You may be wondering why we didn’t opt for some kind of built in BMS? It’s true, there are a lot of options on the market for lithium batteries that come with a BMS built it. Unfortunately this often inflates the cost quite a bit, and puts all these separate pieces like voltage and temperature sensors inside a closed housing. This means if something goes bad, finding and replacing those components will be a huge a pain. Or you might even just have to buy a whole new unit. By keeping things separate, long-term maintenance becomes easier.
That being said, actually connecting our REC BMS was by far the most complicated part of our install. There’s a lot of moving pieces, a lot of wires, and a lot of strange connections. I’ll do my best to illustrate and explain how ours is setup, but make sure you read their manual in all it’s nerdy glory when you go to install your own.
This is our recommended shopping list:
Note: if you go directly to the BMS page, you can add many of these options, build your own bundle, and get extra discounts.
Step 1. Turn off the BMS, pull the cell wiring harness out, and start running individual wires from each battery cell to the corresponding number. You can use small 18 AWG wire. one end will go into the screw terminal, and the other we crimped on ring terminals to go on the positive post of the cell. Keep in mind that the first input in the harness actually goes to your negative connection on the battery. Then you connect to all the positives in order down the line. Do not plug in this wiring harness until later!
Remember how we grouped our batteries in packs of 2? This was so we would have 16 cells which happens to be the exact number of inputs the REC Q BMS has. If we wanted more storage we would need to do it in sets of 16 to continue to create a 48V battery pack. So instead of 32 batteries we’d have to buy 48 and parallel them in packs of 3. If you really need more than 16 cells being monitored, REC does sell a Master Unit that acts as the Primary, and then you can connect multiple Q 16S BMS’s as secondaries underneath it. But that’s more complicated and expensive. We recommend keeping things as simple as possible.
Speaking of cells, if you have less than 16 cells, you can also use the dip switches on the unit to tell it exactly how many you’ll be using. Don’t forget that in this configuration you still have to run a positive connection to the 16th pin.
Wiring up 16 individual cells will take a while, but this will allow the system to not only keep track of each cell of your battery, it’ll also enable that important balancing feature we talked about earlier.
Step 2. Now it’s time to connect your VE.Can Bus communication cable that goes into the back of the Victron Color Control GX. This allows the BMS to talk natively to the central hub of your power system.
The next one gets a little complicated. It can go directly to your REC Touch Display, a small led touchscreen that gives you all sorts of useful info like State of Charge, Cell Temps, Cell Voltage, Amps being used, and more. Or you can connect it through the REC Wi-Fi module.
We highly recommend getting the Wi-Fi Module for a few reasons.
- If you don’t have it, you have to buy some PC software, and use a special RS485 to USB cable to even connect it. Then go through an arduous Windows driver installation setup. Because it connects to your RS485 port, that means any time you want to use it you have to disconnect your display. For someone who is Mac based like me, this would be a huge pain in the butt.
- The Wi-Fi Module stays connected all the time, and is easily accessible from any device via direct Wi-Fi connection. You still get access to the full programming features of the BMS, but in a much simpler and easier to use web version of the application.
- You can also choose to connect it to your existing Wi-Fi network so that any device can connect quickly at any time without needing to connect to the unit’s specific Wi-Fi network
- You’ll likely be doing a lot of tweaking to settings in the beginning, as well as monitoring, so being able to do this on any device is incredibly convenient.
- By the time you buy the PC software and cable, you’re halfway to the cost of the Wi-Fi Module anyway. Totally worth the 100 upgrade.
So yeah, we recommend getting the Wi-Fi Module.
Step 3. That means your RS485 port on the BMS goes into the module’s main communication port. Note there are small positive and negative wires coming out of this cable that need to be connected to your main positive and negative post.
Step 4. Use the Wi-Fi Module’s display cable to connect to the REC BMS Display. This also has negative and positive wires that need to be connected to your main positive and negative post.
Step 5. The temperature sensors. This cable comes with 3 sensors attached, just screw in the connection at the BMS and place the sensors where you like on your batteries with some tape.
Step 6. The current sensor wire will connect directly to the positive and negative output screws on the top of the shunt. This provides an accurate system State of Charge back to the BMS. Remember that the positive side of the shunt is where you battery negative connects, and the negative side of the shunt is for everything else.
Moving on, we have the output wiring harness. Again, make all connections with this unplugged. You’ll plug everything back in later in a certain order.
Step 7. Now, we mentioned the Precharge unit above. Even though this can seem like it’s really over complicating your setup, we think it’s worth installing. According to REC, it “charges the input capacitors of the system components before the main contactor switches on which eliminates high inrush currents at the switch-on of the contactor and prolongs the contactor lifespan dramatically.”
For the BMS wiring harness, you only have two connections. One that goes straight to the “Battery” side of your contactor. And one that goes to the BMS Input on the Precharge Unit.
The rest of the Precharge connections are pretty self explanatory:
- System goes to the “System” side of your contactor
- Battery goes to the “Battery” side of your contactor
- System. goes to the “Negative” side of your shunt
- Contactor goes to the positive contactor wire
- Contactor. goes to the negative contactor wire
Victron Color Control GX VRM Portal
The Color Control GX is the communication center of you entire off-grid power system. It controls all products connected to it, gives live info at a glance, and even creates a Remote Management Portal (VRM) so you can access you system from anywhere in the world.
Before you fire up your system for the first time, you’ll want to make sure everything is connected to this display.
You’ve already connected the REC BMS via the VE.Can Bus, but in order for it to talk directly to everything you’ve got a few more cables to run.
To connect the Quattro Inverter, use a VE.Bus or Ethernet cable. And for the MPPT Solar Charge Controllers, use VE.Direct cables (one for each charger). The display also needs power, so connect its positive and negative wires to the positive and negative of the system.
You may need to put a Terminator Plug into your second VE.Can slot (it comes with one), and if you want to run the VRM portal full time, a USB Wi-Fi adapter will allow you to connect the display to your network. Hardwiring ethernet is also an option. You can even get a USB GPS adapter if your system is on the move. Pretty cool!
Booting for the First Time
At this point, you’ve built out the base of your system. We’ll look at solar chargers and additional inverter connections in a minute, but now’s the time to boot up the system for the first time, and see how things are working.
- Plug in the Outputs wire harness on the BMS(simultaneous)
- Plug in the Cell wire harness on the BMS(simultaneous)
- Turn on the Battery Disconnect Switch
- Turn on the BMS. you’ll see a red light
At this point, the BMS is going to run a bunch of checks:
- Tests balancing switches
- Tests BMS address and cells number
- Tests temperature sensors, self-calibration and EEPROM memory parameters.
After 7 seconds. if all is well. the light on the BMS will turn green, you’ll hear the “clunk” of the contactor, and everything connected to the system side of the contactor will turn on.
REC BMS Settings
The BMS needs the proper settings in order to know how to charge and balance your batteries, as well as passing along crucial information like load and State of Charge to the Color Control GX.
For reference these are the settings REC shared with me for my particular cells. Note: your settings will likely be different. Consult your battery spec sheet, and reach out to REC to get specific numbers for your battery bank.
- Balance Voltage END [V]: 3.55
- Balancing START voltage [V]: 3.4
- END of Charging [V]: 3.55
- END of charging voltage hysteresis per cell [V]: 0.25
- Max allowed cell voltage [V]: 3.75
- Min allowed cell voltage [V]: 2.7
- Max allowed cell voltage hysteresis [V]: 0.2
- Min allowed cell voltage hysteresis [V]: 0.1
- Min Vcell discharge [V]: 2.95
- Shunt: 200A/50mV
- Current sensor coefficient: 0.007813
- Current sensor offset [A]: 0
- Max device charging current [A]: 180
- Max device discharge current [A]: 180
- Charging coefficient [C rating]: 0.5
- Discharging coefficient [C rating]: 1.5
- Minimum allowed temperature for charging [℉]: 32
- Maximum allowed cell temperature [℉]: 150
- Max allowed BMS temperature [℉]: 131
- Max allowed BMS temperature hysteresis [℉] 5
- Operational capacity [Ah]: 560
- Chemistry: LiFePO4 Winston
Victron Color Control GX Settings
For now we’re really just looking to see the Color Control GX has turned on. Remember, the inverter itself should be shut off and the 200A Pole Toggle should also be shut off.
Depending on your setup, you will need to make some adjustments to the settings for the Color Control GX.
- Settings System Setup DVCC
- Main On
- Limit Charge Current On
- Maximum Charge Current On
- Maximum Charge Current 150A
- Maximum Charge Voltage 56.8V
- Shared Voltage Sense On
- Shared Temperature Sense On
- Temperature Sensor REC-BMS battery on Can Bus
- Shared Current Sense On
If you’ve connected everything properly you should see your battery’s percentage, voltage, amperage, and wattage all on the battery portion of the screen.
Keep in mind that most systems will treat the battery pack as 50% full by default until it’s been charged to 100%. So if it is showing a lower percentage than what you think it should be, just be patient.
Now you can test the Inverter. Turn on your 200A Pole Toggle (you might get a spark, don’t worry), and then flip the power button on the Quattro. The green light should turn on, and the Inverter icon on the Color Control GX screen should change add a green light, and change the status to “Inverting.”
Victron Quattro 48V 5,000W Inverter
Congrats, you’ve got power! That’s not to say you’re finished yet, though. It’s time to make more connections. But first, turn everything off in this order:
At this point you should already have your positive and negative trunk wires providing power to the Inverter. and a VE.Bus connection to the Color Control Power Center.
Generator Input Charging
If you want to charge your batteries via a generator, simply run some 6/2 wire to the AC In-1 connection. Then connect the other side of the wire to a 30A plug. Note that we’re now in 3 wire territory. Black is Line, White is Neutral, and Green is Ground. Also know that you’ll need to change the charge settings for your generator input.
Our backup generator is a small Harbor Freight 3500W Predator. But Victron assumes you’ll be using something much larger. I think the default input current limit is upwards of 60A. Our generator puts out about 25A max, so we had to change this setting.
Unfortunately Victron doesn’t make this easy. We had to do the dip switch dance. a very convoluted way to set your input current via tiny switches behind the top panel of the Quattro. I won’t get into this here. you’ll have to read the manual carefully. But once it is changed you’ll see the number for Input Current Limit updated by going to Menu Quattro Inverter on the Color Control GX.
Supposedly you can change this and some other settings by connecting the Quattro to your computer via an MK3-USB cable and software, but we haven’t tried it yet. Maybe one day.
The Quattro requires all grounding cables to be connected together. Not just the main AC in and Out, but also chassis grounds for other equipment. As you can see in the diagram, both solar charge controllers and the Inverter itself all have chassis grounds that should be connected together. Finally, you’ll want to run a minimum 6 AWG bare copper wire to a copper grounding rod per your local electrical codes.
Finally, we get the whole point of this setup. Clean, stable 120V household power! This is as simple as running a romex cable from the AC Out connection to energize your main panel box, and then connecting whatever you want on individual breakers. Because our inverter would be powering multiple things, we used larger 6/2 wire here to the main connections, and then standard romex to individual circuits.
Victron SmartSolar MPPT Solar Charge Controllers
Technically you can connect your solar earlier in the process, but we were still wiring our solar panels, trenching the conduit, and waiting on Amazon to deliver our final circuit breaker so it happened last for us.
Even though we installed combiner boxes at the ground mount array with individual circuit breakers and a lightning arrestor that should prevent any possible power spike to make it into the building, we added additional 40A Circuit Breakers for each main solar line going in front of the charge controllers inside.
This not only doubly protects the charge controllers and batteries, but allows us to completely shut off the solar from the inside of the building. With 7,200W of solar most days we’re running the system completely off of the sun so we need to be able to stop that power flowing through if we’re working on something.
We went with two Victron SmartSolar Charge Controllers (MPPT 250V, 85A). Technically we could have gone through one, but since we were already future proofing by having two combiner boxes and heavy gauge wire run through the conduit, it made sense to set it up with 2 in case we ever put in higher wattage panels one day (highly likely).
The wire runs for these are pretty simple. The positive PV wire goes through the 40A Circuit Breaker and into the PV input on the charge controller. The negative PV wire goes straight to the PV. input on the controller.
Then the Battery connection uses 2 AWG welding wire with crimped ring lugs that flows through a 100A Single Pole Toggle before connecting to the System side of the Contactor.
These 100A breakers act as even more protection for the batteries and system as the power coming out of the MPPT charge controllers is higher than what the panels are putting in. MPPT is cool like that.
The Battery. connection also uses 2 AWG welding wire and connects to the Negative or System side of the Shunt.
Don’t forget those chassis ground connections to the Inverter main ground, and VE.Direct cables to the Color Control GX.
Booting the Solar Charge Controllers
Once all your panels are connected properly, and wires are run from the combiner box through the charge controllers, it’s time to turn everything on.
- Turn on the Battery Disconnect Switch
- Turn on the BMS wait for the Contactor to turn on
- Flip on the breakers in the Combiner Boxes at the solar panel ground mount
- Turn on the 100A Pole Toggle Switches going from the MPPT Charge Controllers to the System
- Turn on the 40A Circuit Breakers going from the solar panel array to the MPPT Charge Controllers
I should note that I did this a bit backwards the first time and caused a bunch of headaches for myself. See, the SmartSolar MPPT Chargers are…well…Smart. They should be able to sense your battery setup and adjust their settings when they’re booted up for the first time.
In my haste to be extra careful, I did not flip on the 100A Pole Toggle Switches until AFTER I turned on the 40A Circuit Breakers. This meant that there was no connection between the MPPT Charger and my batteries so it wasn’t able to auto-sense my setup and defaulted everything to 12V instead of 48V.
As you can imagine, this caused all sorts of failures, alarms, and more. It was assuming my battery pack was over voltage, triggering the BMS contactor. Fun times.
Thankfully the SmartSolar Chargers are Bluetooth enabled. Remember the hoops we had to jump through for the Quattro Inverter? Not the case with these. Just use the VictronConnect app on your phone or laptop to quickly connect and change any setting necessary.
In our case, we needed to make a few important adjustments:
- Settings Battery Voltage 48V
- Settings Battery Preset Lithium Iron Phosphate (LiFiPo4)
- Double check your Absorption and Float voltages as well.
Final Tweaks Adjustments
Congrats. you’ve got power my friend! It’s been a long road, but by building the system and doing the install yourself you’ve saved thousands and thousands of dollars. High Five!
Moving forward I want to set a few expectations. Know that your new battery cells may take some time to balance. They might even overheat the BMS a few times as it works to get them within the right range.
We were constantly tweaking the BMS settings over the first few months trying to get it right, but still had a few shutdowns in the peak of the afternoon in the summer. It did its job, the VRM system sent us notifications, but it was still worrisome.
Finally I reached out to REC BMS, gave them the specs on my batteries, and they replied back with the EXACT settings I needed. I mean, as soon as I entered them the BMS never overheated again, the cells balance each day, and things have been running perfectly.
Don’t be like me. just ask and get the right settings out of the gate. Would have saved me a few months of stress.
Not having these settings right caused all sort of other issues. Because the internal BMS temp was reaching it’s max multiple times a day and rebooting, the Wi-Fi Module and BMS Display were constantly loosing their connection during that reboot cycle. It didn’t affect the data flowing to the Victron Color Control, but it was still annoying.
I also had some initial issues getting the Wi-Fi module to connect to our Wi-Fi network because we are using a cell based setup, and the IP address scheme needed to be manually adjusted.
Thankfully REC’s support was fantastic, and they got me up and running.
Real World Impressions Power Usage
At the time of this writing, we’ve had the system for over 6 months, and couldn’t be happier with the results.
It’s easy to throw around a bunch of theoretical numbers, but seeing this setup run silently and problem free in the background has been amazing. Especially once we got our BMS balancing settings locked in.
Because our house isn’t built yet, we’re still only using a fraction of this system. Currently, we average about 13kWH of solar production each day, and 10kWH of consumption. During the summer when we were running the air conditioner in our Airstream and Mini Split in the Solar Shed, that number was closer to 35kWH.
I’m excited to see how it performs once we have the house built and even more appliances running. Because right now I know we’re just scratching the surface in terms of solar production during the day. It’s usually filled back up by 10 or 11 in the morning.
All in all, this system is a beast, and cost about half of what our neighbors have spent on their own pre-packaged systems. Even better, should we outgrow our current power needs, we can switch out components, solar panels, or add more batteries to create even more capacity and wattage.
What Would We Do Differently?
It’s not all sunshine and roses, though. Hindsight is always 20/20 so now that we’ve been using this system for 6 months full time off-grid. would we change anything?
Understand Alibaba’s payment and shipping better
Like I mentioned in the battery portion, the whole purchasing, deal making, and long shipping times from Alibaba were less than ideal. I had no idea what was going to happen, when it was going to happen, or if it was going happen. I had thousands of dollars invested in other equipment that depended on the batteries making it here. I had hundreds of hours in building our earthbag solar shed and ground mount that depended on these batteries. We had our friends coming to help us install them, it was really hot outside and we needed our air conditioning to work. It was like a giant jigsaw puzzle, and the not knowing was overwhelmingly stressful.
Now I have better idea of what to expect. Payment is weird, the vendors may wheel and deal, and shipping from China takes about 2.5 months. But I got a massive amount of storage at a fraction of the cost. Totally worth it!
Solar Panel Wattage
We bought used 240W panels from Santan Solar during their Sidewalk Sale for an amazing deal. 25 each! We were so psyched to have secured that much power for so little cost.
It wasn’t until we started researching what it would take to build the ground mount to house them on that we realized our mistake. The steel pipe, concrete, and IronRidge pieces totaled nearly 5x the cost of the panels themselves. Holy cow.
If we had to do it again we’d buy higher capacity commercial panels, and build a smaller ground mount.
The only upside here is that if we ever do want more power we can replace the panels we have with higher capacity panels pretty easily and have a TON of solar.
SmartSolar Battery Voltage
Having our charge controllers connected to the battery on boot would have saved us a lot of panicked calls and grief since it defaulted to 12V instead of 48V. We had no idea what was going on, and it took some time to track down why our new solar setup wasn’t working at all.
BMS Balancing Settings
And finally, let me reiterate again that I should have reached out to REC so much earlier regarding my balancing settings. If I had let this continue long term I probably would have fried the components of the BMS since it was overheating so many times a day.
This stuff is complicated, so don’t be afraid to ask Smart people for help.
Since installing this system, the Summer of 2022 brought a historically strong monsoon season with epic storms, and a rogue indirect ground lighting strike that took out our Victron inverter, one of our charge controllers, and our BMS display.
This cost us thousands of dollars to replace, and we were without power for nearly a week. It sucked. Real bad.
It also led us to a months long journey researching additional lighting protection, desert soil conditions, warranties and even insurance.
We’ve written a new article and created a new video explaining what happened and what precautions we’re taking in the future:
Now you may be asking, “How much did all this cost again? Didn’t you say it was way cheaper?” Great question. With this article approaching 10,000 words, I’ve decided to create a separate cost breakdown and spreadsheet calculator to make sure it’s not too overwhelming.
Also I’ve tried to include links to each piece of equipment in this installation article so you can go ahead and start purchasing the necessary pieces if needed.
I’ll add the link to the cost breakdown here as soon as it’s ready. UPDATE: the cost breakdown is complete! See how much we spent total here.
How much will your off-grid solar system cost?
Get a better understanding of your project save thousands of dollars with our solar cost calculator!
Besides the intelligent spreadsheet, it includes includes links to everything we bought for our off-grid solar power install nearly 1 hour of behind the scenes videos with additional thoughts, details, tips!
Whew! I’m not sure how I keep talking myself into writing these massively detailed posts, but here we are again.
Thanks to the internet, there is so much great information out there about DIY solar systems. While it’s my job here to do that research and compile what I’ve learned to make the best power system decision for me and my family, I couldn’t end this article without giving a shout-out to those that have come before us.
- Beginning from This Morning. by far Juan and Michelle were our biggest influence for the overall big ideas as well as detailed implementation like wiring the BMS and building the battery boxes. We could not have done this without them!
- Wild Wonderful Off-Grid and Handeeman. Both of these channels helped us understand how to build our massive solar ground mount.
- Will Prowse of DIY Solar Power. Should you need to go deep down the rabbit hole of all things lithium battery banks, Will is a wealth of information and does extensive testing. Highly recommended.
I hope our installation breakdown and wire guide give you a better understanding of how to build your own large off-grid solar power system, and do it in a way that is safe, stable, and cost effective.
If you found this interesting I have to let you know that we’re just getting started here on our off-grid homestead. Besides building all sorts of unique, sustainable structures we’ll be setting up rainwater catchment, even be creating other smaller independent solar systems for various uses. So much going on, and we’d love to share it with you! Make sure you’re subscribed so you don’t miss our next project.
Download Our Solar Wiring Diagram
Get up close and personal with this super detailed, impeccably illustrated hi-res PDF of our full off-grid power setup with a schematic representation of how everything in our 7200W, 28kWH, 120V off-grid battery and solar system connects together. Includes bonus individual component wiring configs, too!
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About the Author
Jonathan Longnecker is the strongly opinionated tattooed and bearded half of Tiny Shiny Home. He loves making music, figuring out nerdy solutions, exploring the outdoors, and living off-grid.
Solar installations are getting easier all the time and there’s plenty of do-it-yourself information out there. But are you ready to go the DIY route?
If you’re interested in solar power, surely you already know that solar electricity is good for the environment, national security, and the air we breathe, not to mention your electricity bill. And that it’s one of the best ways to reduce your household’s contribution to global warming. You’ve also probably heard that going solar can actually be cheaper than paying for utility power, and you might wonder whether this claim is true. Well, in most cases, it is true. It just takes time for the incremental savings to overtake the initial investment (after that, the solar power is free). If you install the solar system yourself, you can hit this tipping point a lot sooner — in some cases, in half the time.
That brings us to the next big question: Can you really install your own solar panels? Again, the answer is yes. If you can drive lag bolts and assemble prefabricated parts, and if you’re willing to spend a day or two on your roof (or not, if you’re mounting your panels on the ground), you can install your own solar system. You don’t have to know how to hook up the solar panels to your household electricity or the utility grid. You’ll hire an electrician for the house hookup, and the utility company will take care of the rest, usually for free. For a completely off-grid system, the utility company isn’t involved at all.
Perhaps disappointingly, this job isn’t even a good excuse to buy new power tools, since the only one you need is a good drill.
So, if this is such a doable project, why do most people use professional installers? For starters, a lot of people have good reasons to hire out virtually everything, from oil changes to grocery shopping. (That’s probably not you, but even if it is, our book can help you plan for a solar installation and find a good local installer.) Solar professionals handle more than the installation. They design the system, they apply for rebates and credits, they order all the necessary parts, and they obtain the permits and pass all the inspections. But the fact is, you can do all of these things yourself, provided you have a helpful adviser and you are willing to follow the rules of the local building authority (that’s where you’ll get those permits).
Solar installations are getting easier all the time, and you might be surprised at how much do-it-yourself (DIY) help is available. Two good examples are PVWatts and the Database of State Incentives for Renewables Efficiency (DSIRE). PVWatts is an online calculator that helps you size a solar-electric system based on the location and position of your house and the angle of your roof. Solar pros use the same simple tool, but it’s free for everyone. DSIRE offers an up-to-date, comprehensive listing of renewable energy rebates, tax breaks, and other financial incentives available in any area of the United States. And it’s also free and easy to use.
Those two resources alone help answer the two most common questions homeowners have about solar electricity: How big of a system do I need? and How much will it cost? Other resources include solar equipment suppliers that cater to DIYers and offer purchasing and technical support, as well as online communities like Build It Solar. And there’s no law that says DIYers can’t hire a solar professional for help with specific aspects of their project, such as creating design specifications, choosing equipment, or preparing permit documents.
We should also say up front that installing your own solar panels is not a process well-served by cutting corners. We don’t want you to install your system without a permit or without hiring an electrician to make the final hookups. (Even professional solar installers use electricians for this stuff.) The permit process can be a pain, yes, but it’s there to ensure that your system is safe, not just for you but also for emergency responders who might need to work around your mini power plant. When you work with the local building department you also learn about critical design factors, such as wind and snow loads, that are specific to your area.
Can I Install My Own PV (Photovoltaic) System? A DIYer’s Checklist
It’s time for the litmus test that tells you whether to proceed boldly as an amateur solar installer or to hand over the reins to a professional. For most of you, the decision will come down to the rules of the local building authority (most likely your city, county, township, or state) or your utility provider, either of which may require that solar installations be done by a licensed professional. This is also the best time to confirm that your project won’t be nixed by your zoning department, historical district standards, or your homeowner’s association.
- Amateur installation is permitted by the local building authority and your utility provider.
- Requirements for amateur installation are reasonable and acceptable. Some authorities require nonprofessionals to pass tests demonstrating basic knowledge of electrical and other household systems, but such tests may not be extensive.
- You’re okay with several hours of physical rooftop work (those with ground-mount systems get a pass here) AND you’re wise enough to wear legitimate fall-arresting equipment (not a rope tied around your waist). You may feel as confident as Mary Poppins dancing on rooftops, but she can fly; you should be tethered.
- You don’t live in a historical district or, if you do, the zoning authority permits PV systems (with acceptable restrictions).
- Your homeowner’s association, if you have one, permits PV systems (with acceptable restrictions). Sometimes the homeowner’s association may need a little nudging to give permission.
- You have a standard type of roofing (asphalt shingles, standing-seam metal, wood shingles, standard flat roof). If you have slate, concrete tile, clay tile, or other fragile/specialty roofing, consult a roofing professional and/or hire out the PV installation. This is not necessarily a deal-breaker.
TEXT EXCERPTED FROM INSTALL YOUR OWN SOLAR PANELS © JOSEPH BURDICK AND PHILIP SCHMIDT.
Install Your Own Solar Panels
Labor and related costs account for more than half of the price of the average home solar installation. But homeowners can save thousands of dollars with this user-friendly manual, which follows the same process professional contractors use. Through detailed directions and step-by-step photos, veteran solar installer Joseph Burdick and seasoned builder Philip Schmidt teach you how to determine the size, placement, and type of installation you’ll need. This comprehensive DIY guide covers everything from assembling rooftop racking or building a ground-mount structure to setting up the electrical connections and making a battery bank for off-grid systems.