Solar Integration: Inverters and Grid Services Basics
An inverter is one of the most important pieces of equipment in a solar energy system. It’s a device that converts direct current (DC) electricity, which is what a solar panel generates, to alternating current (AC) electricity, which the electrical grid uses. In DC, electricity is maintained at constant voltage in one direction. In AC, electricity flows in both directions in the circuit as the voltage changes from positive to negative. Inverters are just one example of a class of devices called power electronics that regulate the flow of electrical power.
Fundamentally, an inverter accomplishes the DC-to-AC conversion by switching the direction of a DC input back and forth very rapidly. As a result, a DC input becomes an AC output. In addition, filters and other electronics can be used to produce a voltage that varies as a clean, repeating sine wave that can be injected into the power grid. The sine wave is a shape or pattern the voltage makes over time, and it’s the pattern of power that the grid can use without damaging electrical equipment, which is built to operate at certain frequencies and voltages.
The first inverters were created in the 19th century and were mechanical. A spinning motor, for example, would be used to continually change whether the DC source was connected forward or backward. Today we make electrical switches out of transistors, solid-state devices with no moving parts. Transistors are made of semiconductor materials like silicon or gallium arsenide. They control the flow of electricity in response to outside electrical signals.
A 1909 500-kilowatt Westinghouse “rotary converter,” an early type of inverter. Illustration courtesy of Wikimedia.
If you have a household solar system, your inverter probably performs several functions. In addition to converting your solar energy into AC power, it can monitor the system and provide a portal for communication with computer networks. Solar-plus–battery storage systems rely on advanced inverters to operate without any support from the grid in case of outages, if they are designed to do so.
Toward an Inverter-Based Grid
Historically, electrical power has been predominantly generated by burning a fuel and creating steam, which then spins a turbine generator, which creates electricity. The motion of these generators produces AC power as the device rotates, which also sets the frequency, or the number of times the sine wave repeats. Power frequency is an important indicator for monitoring the health of the electrical grid. For instance, if there is too much load—too many devices consuming energy—then energy is removed from the grid faster than it can be supplied. As a result, the turbines will slow down and the AC frequency will decrease. Because the turbines are massive spinning objects, they resist changes in the frequency just as all objects resist changes in their motion, a property known as inertia.
As more solar systems are added to the grid, more inverters are being connected to the grid than ever before. Inverter-based generation can produce energy at any frequency and does not have the same inertial properties as steam-based generation, because there is no turbine involved. As a result, transitioning to an electrical grid with more inverters requires building smarter inverters that can respond to changes in frequency and other disruptions that occur during grid operations, and help stabilize the grid against those disruptions.
Grid Services and Inverters
Grid operators manage electricity supply and demand on the electric system by providing a range of grid services. Grid services are activities grid operators perform to maintain system-wide balance and manage electricity transmission better.
When the grid stops behaving as expected, like when there are deviations in voltage or frequency, Smart inverters can respond in various ways. In general, the standard for small inverters, such as those attached to a household solar system, is to remain on during or “ride through” small disruptions in voltage or frequency, and if the disruption lasts for a long time or is larger than normal, they will disconnect themselves from the grid and shut down. Frequency response is especially important because a drop in frequency is associated with generation being knocked offline unexpectedly. In response to a change in frequency, inverters are configured to change their power output to restore the standard frequency. Inverter-based resources might also respond to signals from an operator to change their power output as other supply and demand on the electrical system fluctuates, a grid service known as automatic generation control. In order to provide grid services, inverters need to have sources of power that they can control. This could be either generation, such as a solar panel that is currently producing electricity, or storage, like a battery system that can be used to provide power that was previously stored.
Another grid service that some advanced inverters can supply is grid-forming. Grid-forming inverters can start up a grid if it goes down—a process known as black start. Traditional “grid-following” inverters require an outside signal from the electrical grid to determine when the switching will occur in order to produce a sine wave that can be injected into the power grid. In these systems, the power from the grid provides a signal that the inverter tries to match. advanced grid-forming inverters can generate the signal themselves. For instance, a network of small solar panels might designate one of its inverters to operate in grid-forming mode while the rest follow its lead, like dance partners, forming a stable grid without any turbine-based generation.
Reactive power is one of the most important grid services inverters can provide. On the grid, voltage— the force that pushes electric charge—is always switching back and forth, and so is the current—the movement of the electric charge. Electrical power is maximized when voltage and current are synchronized. However, there may be times when the voltage and current have delays between their two alternating patterns like when a motor is running. If they are out of sync, some of the power flowing through the circuit cannot be absorbed by connected devices, resulting in a loss of efficiency. total power will be needed to create the same amount of “real” power—the power the loads can absorb. To counteract this, utilities supply reactive power, which brings the voltage and current back in sync and makes the electricity easier to consume. This reactive power is not used itself, but rather makes other power useful. Modern inverters can both provide and absorb reactive power to help grids balance this important resource. In addition, because reactive power is difficult to transport long distances, distributed energy resources like rooftop solar are especially useful sources of reactive power.
A worker checks an inverter at the 2MW CoServ Solar Station in Krugerville, Texas. Photo by Ken Oltmann/CoServ.
Types of Inverters
There are several types of inverters that might be installed as part of a solar system. In a large-scale utility plant or mid-scale community solar project, every solar panel might be attached to a single central inverter. String inverters connect a set of panels—a string—to one inverter. That inverter converts the power produced by the entire string to AC. Although cost-effective, this setup results in reduced power production on the string if any individual panel experiences issues, such as shading. Microinverters are smaller inverters placed on every panel. With a microinverter, shading or damage to one panel will not affect the power that can be drawn from the others, but microinverters can be more expensive. Both types of inverters might be assisted by a system that controls how the solar system interacts with attached battery storage. Solar can charge the battery directly over DC or after a conversion to AC.
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Home » Solar Information Resources » Solar Integration: Inverters and Grid Services Basics
How Solar Power And The Grid Work Together
The popularity of producing clean energy with your own solar power system continues to increase. As more people are going solar, utility companies are using programs like net metering to help integrate solar power and the grid.
We believe the solar power industry and the electric grid can enjoy mutual benefits through increased energy supply that stabilizes when, where, and how electricity is generated and distributed.
When thinking about solar power, it’s helpful to understand how home solar, solar companies, utilities, and the power grid can all work together to better serve the electricity needs of the population.
How Does the Electricity Grid Work?
The day-to-day operations of the electricity grids in the United States are rather straightforward, as utility companies have used the same top-down model for over a century. Here is a breakdown of the process:
- Generation: Big power plants generate power. Step-up transformers increase the voltage of that power to the very high voltages needed for transmission.
- Transmission: The generated power travels long distances over high-voltage transmission lines.
- Conversion: At local facilities, the high-voltage power flows through step-down transformers to become lower voltage.
- Distribution: Distribution wires carry lower voltage electricity from transformers to homes and businesses in the area.
- Transformation: The transformers on power poles further lower the voltage to consumption level.
- Connection: Electricity enters your home or business via the electricity meter which keeps track of consumption.
The Relationship Between Your Solar Power System and the Electric Grid
Despite what people often think, going solar doesn’t necessarily mean you’re going to be off-the-grid. In fact, no conversation about how solar energy works would be complete without discussing the relationship between solar power and the grid. This is because the vast majority of homes that install solar panels still draw power from the grid that the utility companies help operate.
So why does your home need power from the grid after solar panel installation? The simple answer is that remaining connected to the grid allows your home to draw additional power when solar panels can’t generate enough electricity, including nights and cloudy days. At the same time, your home can also push additional power back into the grid when your home doesn’t need all of the electricity being generated, such as in the middle of a sunny day when everyone is away from the house.
For most homes, your residential solar power system will probably be grid-tied, more commonly known as on-the-grid. When grid-tied, your solar panel system is connected to the grid via a bi-directional electricity meter. It measures the excess power you send to the grid when your solar panels produce more than you need, and the amount of energy you pull from the grid when your solar panel system doesn’t generate enough.
If you are truly off-grid, you are not connected in any way to the local grid. That means there are no distribution wires from the power line to your home. You are entirely reliant on the electricity your solar panels produce to meet your energy needs, and there’s no backup in case of a power outage or other issue.
Off-grid living requires you to take some extra steps to be successfully disconnected from the grid, including generating energy from multiple sources, solar power battery storage, and home design that minimizes excess energy usage.
Net Metering Credits Homes That Add Solar Power To The Grid
A net metering program credits homeowners when they generate electricity and send that excess generation to the grid. If your utility company offers net metering and you participate in the program, every excess kilowatt-hour (kWh) of energy you send to the grid counts as credit towards your future energy consumption.
The more excess power generated and fed to the electricity grid, the more credit you will earn, which will help offset the energy you use when your solar power system doesn’t create enough electricity to power your home. Thus, your electricity bill is based on the total electricity you used, relative to the total energy you generated and fed to the grid.
Most people consume more electricity in the morning when getting ready for the day, and in the evening when they get home from work. Net metering ensures you get the most value from the energy generated by your solar power system, especially in the afternoon, which happens to be when you typically consume less electricity.
The excess energy you generate goes to the grid, earning you credit while also helping the grid by reducing electricity demand. Keep in mind that electricity demand is usually highest during the day when most businesses are open, so feeding your surplus energy back to the grid helps meet this increased demand.
If you wish to participate in net metering, make sure to find out if it is available in your area and how it will help offset your usage. One easy way to do so is with Palmetto’s Free Solar Savings Estimate. Once you find out how much you could save by going solar, just enter your contact information and one of our solar experts can review the programs that are available in your area, and help you understand how to take advantage of them.
Time-of-Use Plans Align Rates with Demand on the Grid
Time-of-use rates allow utility companies to adjust the rate of pay for electricity over the course of the day. When demand goes up, rates go up as well, and when demand drops, homeowners can pay less for the electricity they need.
On a time-of-use rate plan, your photovoltaic (PV) system’s excess solar energy generation in the middle of the day is usually less valuable than the power you draw from the grid at night. During peak sun hours, solar-powered homes often add more electricity to the grid than they use, so utility companies don’t want to pay as much for that electricity because of the increased supply.
When the sun goes down, utilities can then charge homeowners more per kWh for the electricity they draw from the grid as demand outpaces supply.
If you live in an area with time-of-use rate structures, you may be able to save more money by storing the excess energy generated by your solar panels during peak sun hours, and then using your solar power storage later in the day when rates are highest. This requires the installation of battery storage as part of your solar power system, which can help you save more money by circumventing the peak utility charges at night.
How Solar Power Helps the Grid
While there is some interaction between solar power and the grid operated by utility companies, it can often seem like they operate independently from each other. However, installing solar panels on your home can actually help the electric grid, so we think that the relationship between solar homes and the electric grid should be strengthened.
From helping lower the electricity demand and reducing grid stress to increasing generation, going solar helps support the grid in various ways:
Solar Power Smooths Out The Grid’s Demand Curve
The demand curve is how the energy industry describes the increase and decrease in consumer demand for electricity relative to supply in a given day.
By adding electricity to the grid with your solar panels, you reduce the peaks of that curve because people can use the energy you generated without the utility companies ramping up their power plants to meet consumer demand. Thus, the grid doesn’t experience massive spikes in demand because solar energy generation is available from grid-tied panels.
Solar Power Reduces Grid Stress
When you go solar, you help reduce the amount of electricity that needs to be moved across transmission and distribution lines. Solar energy lowers the stress on the electricity grid because most solar energy stays in the area where it’s generated, and doesn’t need to be transmitted long distances. As a result, the transmission lines get a breather during the hottest parts of the day when demand is highest.
Solar Power Helps Lower The Cost of Grid Upgrades and Maintenance
Going solar helps offset the need for spending on both new generation and new transmission infrastructure. When solar power enters the grid (instead of energy from fossil fuels) the reduced grid stress translates into lower operating costs for utility companies thanks to reduced maintenance expenses. The less money the grid needs to spend to fix problems, the less you have to pay on your utility bills over time to cover that expense.
How Solar Energy and the Electricity Grid Don’t Get Along
Even with the benefits they provide, many utility companies aren’t excited about the growth in homes with solar power systems. Afraid of losing revenue and influence in the energy industry, the people in charge of the electricity grid have started looking for ways to make going solar more challenging for people. Their perceived problems with the recent growth of solar power and the grid boil down to five factors:
Solar Energy Reduces Income for Utilities
Homeowners with rooftop solar panels purchase less energy from the grid and pay less to the utility companies. People who participate in net metering programs can sometimes produce enough surplus electricity to offset the majority of their utility bills, so they end up paying almost nothing to their utility company.
While this is a good thing for consumers, the environment, and the long-term health of the grid, some utility companies are concerned about how rooftop solar may reduce their potential earnings in the future.
Solar Energy Increases The Fear of Competition
In many places, the utility company has basically operated as a monopoly for many years, which means they haven’t had to compete in the open market to “win” their customers. Now that solar panels give homeowners an alternative to how they get power, utilities have to compete in ways they’ve never had to in the past.
Furthermore, as the cost of solar decreases and efficiency increases, the technology approaches grid parity, which is when solar power costs less than, or equal to, the cost of electricity from conventional fossil fuel sources like coal, oil, and natural gas. The goal of grid parity is to make solar more affordable than fossil fuel power, even without tax credits or other incentives, which would drastically increase the competitiveness of clean energy.
This increase in solar installations worries utility companies because they view it as consumers paying less for grid operations. In many places, the utilities are so concerned about consumers becoming power producers that they’re seeking additional restrictions on solar energy production and net metering to prevent that competition.
Solar Energy Doesn’t Provide Predictable Generation
While solar panel systems can generate a lot of electricity and add it to the grid, they can’t do so all the time. When the sun isn’t shining, energy production decreases, so there’s no way to just ‘turn on’ more solar energy like you can with fossil fuel electricity generation.
Solar Energy and The Grid are Built Differently
The current power grid is designed to support electricity transmission that starts at large power plants and gets distributed out to consumers. Compared to the grid’s top-down model, solar panels are designed to work using a distributed model.
Distributed generation focuses on electricity production at or near where it will be used, with a big FOCUS on the electricity created by photovoltaics. While energy from solar panels can be fed to the electric grid to support clean power and reliable delivery, the current grid configuration needs some improvement for the two distribution infrastructures to work seamlessly together.
Solar Energy Uses the Grid Without Paying for It
On a grid-tied system, homeowners with rooftop solar panels generate the electricity they need, feed the surplus to the grid, and only turn to the grid when their systems aren’t generating enough to meet their needs. Utility companies feel they need to be allowed to recover the costs associated with maintaining the grid infrastructure that solar-powered homeowners stay connected to, even if they don’t pull power from it all the time.
At Palmetto, we feel that no customer wanting to go solar and participate in net metering should be penalized. Solar energy helps the planet by reducing our reliance on fossil fuels, and home solar plays a big role in easing pressure on the aging grid by lowering overall electricity demand.
How the Utility Grid and Solar Energy Companies Can Work Together
The world is getting more focused on using renewable energy sources for a pollution-free planet, but the grid is not yet ready to fully integrate renewable energy technologies. A significant upgrade is necessary for that to happen, and can be made easier if solar companies and utility companies join hands. (It’s a concept we call the New Utility Revolution.)
The utility companies should be ready to accept that the time for a change is here, and look for ways to upgrade the current top-down system to support distributed generation. This new Smart grid has the potential to benefit solar homeowners, utility companies, and the grid at the same time, but only if everyone works together for the greater good.
Embracing distributed generation, focusing on increasing solar generation, and investing in solar technologies are some of the things the utilities should consider implementing to help solar power and the grid work together.
Focus on Increasing Solar Generation
The aging US electricity grid already struggles to meet the rising energy demands of modern homes filled with electricity-powered devices. With consumption increasing by the day, a shift to renewable energy to address that additional demand is more viable and timely. Instead of seeing solar companies as competitors, utility companies should start seeing how they can empower them to produce more clean energy in the future.
Embrace Distributed Energy Generation
Utility companies feel disadvantaged by the growth of solar technologies. Both the current regulations and the new ones they seek are a major blow to increasing and improving clean energy generation. Instead of ignoring the benefits of solar energy and its growing popularity, utility companies should adapt by creating a conducive environment for their counterparts, working together to create and distribute the electricity that we all need.
Invest in Solar Technology
Renewable energy sources like solar panels are the wave of the future, and that won’t change any time soon. For that reason alone, utilities need to think of ways to be part of the trend, instead of working against it. This starts with efforts like developing utility-scale solar, increasing net metering options, and improving the grid to allow for better distributed energy generation.
Utility companies can also invest in solar companies and solar technologies, setting themselves up to share in the success of this clean energy revolution, instead of just seeing those companies as competition.
Key Takeaways
Solar power is a key element of the greater renewable energy movement that’s helping to mitigate climate change. While solar companies work tirelessly to develop better solar technologies, utility companies can take steps to work with, and adapt to this new norm. Programs like net metering and time-of-use rates are helping solar power and the grid work better together, but more can be done to adapt to the needs of solar-powered homes.
Solar power helps the grid in many different ways, such as smoothing out the demand curve, reducing grid stress, and lowering the cost of grid upgrades and maintenance. Grid operators need to find ways to keep up with modern solar technologies to better serve the electricity needs of the population. People want to go solar, and utility companies should be proactive to this trend, not reactive or combative.
If you are interested in going solar to lower your utility bills and help the electricity grid, Palmetto can help you achieve those goals. Our experts will analyze your home’s energy needs, recommend the best solar energy system for you, and guide you through the entire installation process from start to finish.
Off-Grid Solar System Design Installation Guide
So, you’ve decided to start your journey to off-grid living.- congratulations! Installing an off-grid solar setup can be intimidating, so we’ve put together this complete guide to off-grid solar system design and installation to help guide your project.
Inside, you’ll find a complete overview of the process of going off the grid with solar, including detailed calculations to help you size an off-grid system that precisely fits your needs. We’ll also outline how to build an off-grid solar system that is safe and code-compliant.
Off-grid solar systems are not the same as grid-tie solar systems. With an off-grid system, you are entirely independent of the grid and 100% responsible for your power needs. You won’t be able to harness extra electricity from the utility company. Learn more about off-grid vs. grid-tie systems.
Shop Off-Grid Kits
Ready to add an off-grid solar system to your home? Speak to one of our off-grid solar experts today!
Off-Grid Solar System Components
Here’s a quick overview of the parts you can expect to find in your off-grid solar system. It’s important to pick components specifically rated for off-grid use. For example, most grid-tie inverters are not configured to connect to a battery bank.
Solar Panels
Solar panels absorb the sun’s rays, converting sunlight into DC (direct current) power.
While you may find that some panels are marketed as “off-grid solar panels,” this is a bit of a misnomer. There used to be panels that were designed to match the lower voltages of specific types of charge controllers and battery banks, but the technology has improved enough that the design standard has become outdated. Nowadays when a panel is marketed as off-grid it often means that the wattage is lower than the current standard, and many of the panels marketed this way tend to be of inferior quality.
Now, MPPT charge controllers allow us to make use of standard, mass-produced solar panels in off-grid applications. Any traditional 60/120 or 72/144 cell solar panel will work just fine, and if you have space on your property to mount full-sized panels, that will be your most cost-effective option.
Common solar panel sizes:
Both 60-cell and 120-cell solar panels are about 3.5 feet by 5.5 feet. The difference is that 120-cell panels utilize half-cut cells, which are slightly more efficient and resistant to failure.
72-cell and 144-cell solar panels are about 3.5 feet by 6.5 feet, with 144-cell panels using half-cut cells as well.
60/120-cell panels are easier to carry and offer more flexible design options, while 72/144-cell panels cost less to install. Compare 60/120 vs. 72/144-cell panels here.
Cost/Watt
Weight
Monocrystalline (mono) solar panels are cut from a single section of silicon. They are slightly more efficient than polycrystalline (poly) solar panels, which contain cells made of blended fragments of silicon.
Mono solar panels cost a bit more than poly panels, because their increased efficiency allows you to fit more solar in a smaller space. In terms of performance, mono and poly solar panels will produce power equally well, but an array of poly panels would take up more room on your property.
Batteries
The centerpiece of off-grid solar systems. Batteries store the energy you produce. You can draw power from your battery bank to run your appliances at any time.
Off-grid solar systems use deep cycle batteries, which are designed to be discharged and recharged gradually. Typically solar batteries are sized to cover your energy usage for one night and recharge from solar during the day, completing one charge / discharge cycle over a 24 hour period.
Some common battery types used in off-grid solar applications:
Flooded Lead Acid Batteries
Flooded lead-acid (FLA) batteries are sometimes referred to as wet cell batteries because the electrolyte is in liquid form and can be accessed by removing the battery caps.
Charging flooded batteries causes water in the electrolyte solution to evaporate, so they regularly need to be refilled with distilled water to keep them topped off. This need for routine maintenance means flooded batteries are only suitable for those who have the time (and the desire) to perform maintenance checks on their battery bank on a monthly basis.
FLA batteries are especially prone to failure if not properly maintained, and we find that most people can’t (or won’t) commit to the monthly maintenance schedule needed to properly care for FLA batteries. Their strict maintenance requirements means they are not suitable for vacation homes, nor would we recommend them for full-time off-grid residences, unless you really love the idea of getting hands-on with your system.
Sealed Lead Acid Batteries
Sealed lead acid (SLA) batteries get their name because the compartment containing the electrolyte is sealed, which prevents leaks and noxious fumes coming from the battery.
Unlike flooded lead-acid (FLA) batteries, sealed batteries have minimal maintenance requirements and do not need to be installed in a ventilated battery enclosure. SLA batteries can also be mounted in any orientation, because the contents of the battery are sealed shut.
There are two sealed lead acid battery types: absorbent glass mat (AGM) and gel batteries.
- AGM batteries are less expensive and perform better than gel batteries in cold temperatures. They are also capable of higher charge and discharge rates. They are the more cost-effective sealed battery option, recommended in most off-grid solar applications.
- Gel batteries are an older technology that cost more than AGM batteries. They take longer to charge and are not as widely available as AGM. Gel batteries do perform better in high ambient temperatures, so they may make sense in hot climates, but AGM is usually the more cost-effective option.
Lithium Ion Batteries
Lithium Ion batteries tend to be about 3x the cost of SLA batteries, but they also last about 3x longer, so the higher initial cost balances out over the life of the system. (For a lifetime cost comparison chart, see the “Cost of Off-Grid Solar” section below.)
If you want a high performance battery that you don’t have to replace for a decade, lithium batteries are the most convenient option. They have faster discharge and recharge rates, weigh less and are maintenance-free. In addition, lithium batteries are modular, meaning you can start small and expand your battery bank as needed.
# of batteries
Storage Capacity
warranty
temperature range
Charging Temperature 32°F to 114°F
Discharging Temperature.4°F to 131°F
Off-Grid Inverters
The inverter is the central hub of the system, responsible for routing power between its various components. For off-grid solar, you need an inverter that is purpose-built for off-grid use.
State of the art off-grid inverters have a variety of capabilities and Smart functions. MPPT charge controllers are built in to many inverters. Some not only accept generator power inputs, but can start the generator if battery power dips too low. Inverters include the brain for monitoring systems so that you can monitor your system remotely. And if you are using lithium batteries, many inverters can communicate directly with the battery’s built in BMS (Battery Management System) in order to maintain proper charge levels and to make battery bank information available for your monitoring.
Your off-grid inverter takes low voltage DC power from the battery bank and converts it into 120/240V AC, the standard format that powers household appliances.
State of the art off-grid inverters offer several Smart features to manage your system. A few examples include remote monitoring, automatic generator start, and the capability to communicate directly with lithium battery banks to monitor and maintain proper charge levels.
Racking
The foundation that supports your solar array. We recommend the Ironridge XR metal rail system.
Racking is universal between grid-tie and off-grid systems. There’s no special equipment; it’s just a metal structure that supports the weight of the solar array.
Both roof and ground mount racking works well, and there are pros and cons to both options. Take a look at our article comparing ground mount vs. roof mount solar if you’d like help deciding where to mount your array.
Charge Controllers
A solar charge controller regulates the battery charging process. Charge controllers keep solar panels from overcharging your battery bank by regulating the voltage the panels generate.
48-volt batteries are common in off-grid systems; however, most solar panels deliver more voltage than is required to charge the batteries. Charge controllers convert the excess voltage into amps, keeping the charge voltage at an optimal level while reducing the time necessary to charge the batteries fully.
Undercharging and overcharging both reduce the expected lifespan of your battery bank, so it’s important to pick the right controller and properly program the charging profile of the batteries.
There are two main types of charge controller: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracker).
- PWM controllers are an older technology that we do not recommend for off-grid homes. They are less efficient and have limited options for compatible solar panels. PWM controllers are better suited for less intensive applications, like remote telecom setups.
- MPPT controllers are a more efficient and reliable technology that maximizes the current running into the battery bank. As the intensity of sunlight changes throughout the day, MPPT controllers automatically adjust the voltage to charge the battery bank as efficiently as possible. We exclusively use MPPT charge controllers in our solar kits to meet the demands of full-time off-grid living.
Power Center
A power center is a pre-wired unit that contains the “brains” of the system.- the inverter, charge controllers, monitoring system, overcurrent / surge protection, AC and DC inputs/outputs, and wiring to tie it all together.
Buying a pre-wired power center, or a state of the art off-grid inverter that has most of these features built-in, saves the intricate work of correctly mounting and wiring a number of components together.
How much does it cost to go off grid with solar?
First, the standard disclaimer: every off-grid solar project is different, and your costs will vary (™). To put together a custom off-grid solar package that suits your needs, reach out to us for a free PV proposal.
However, it can be useful early in the research process to look at some sample systems to help benchmark the costs of off-grid solar. Feel free to take a look at our off-grid solar kits in our shop for up-to-date pricing.
Please note that the kits in our shop do not include the cost of batteries, as the battery bank will need to be sized to match your energy consumption (we’ll explain how to do that in the Off Grid Solar System Design section).
Tax Incentives Polices by State
You are eligible to claim the solar tax credit if:
- You owe taxes for the filing year that the system was installed
- The system is installed at your primary residence
- You are the owner of the system (leases / PPAs do not apply)
Backup Generator Costs
While solar can handle your day-to-day power needs, most off-grid systems are designed for a single day of autonomy (days that you can fully meet your energy needs with solar). You will inevitably encounter stretches of bad weather where your solar panels can’t produce enough power to cover your needs.
For that, off-grid systems must include source of backup power. For most people, that means adding a backup gas generator to get through periods of low solar production.
Be sure to budget for a backup generator as part of the overall cost of your system.
Need Help?
We’ll help you design an off-grid solar system. Whether you’re converting an existing system to off-grid or starting from scratch, we can guide you to the best energy-saving solution.
Minimizing Off-Grid System Costs
Before you size your off-grid solar system, consider whether you can take measures to reduce your energy usage. Lower consumption means you can get away with a smaller battery bank and inverter, reducing system costs.
Two simple things to consider:
- Propane Appliances Consider outfitting your off-grid home with propane appliances to limit your electricity usage. We recommend looking for a propane stove, clothes dryer, wall heater and on-demand water heater; in our experience these are more cost-effective than running them off electricity. Be sure that you have reliable access to a propane vendor near you. Some places have propane delivery services, which are convenient.
- Stagger Appliance Usage Usage Off-grid systems are designed with peak consumption in mind.- how many electrical loads are run simultaneously. By staggering your usage of major appliances, you can reduce the peak demand on your system. For example, if you’re willing to run your dishwasher and laundry at different times, that will reduce peak demand and keep system costs in check.
Off-Grid Solar System Design
Off-grid living means you are fully responsible for your own power production; if your energy storage doesn’t live up to your needs, there’s no grid power to fall back on. For that reason, it’s critical to take all the factors that impact solar production into account during the system sizing process.
Factors that Impact Off-Grid System Design
Before we get into the system sizing process, consider the following:
Sun Hours Some parts of the country get more exposure to the sun than others. You’ll need to know how many sun hours you get in your location.- a measure of the duration and intensity sunlight in your region. Fortunately there’s no guesswork involved, thanks to the solar insolation maps provided by the National Renewable Energy Laboratory (NREL). Look for the DNI (Direct Normal Irradiance) maps and take a note of the average sun hours in your location. Most places in the US fall in the range of 4-5 sun hours per day. You may notice from the monthly maps that sun hour availability dips dramatically in the winter. Your solar production will fall below your needs in the winter months, and it will be up to your generator to pick up the slack. While you could theoretically oversize your solar array so that it works in those bleak winter months, it would be insanely expensive (think triple the system costs). It’s much more cost-effective to size your solar array to be effective most of the year, but let the generator take over in the winter.
Obstructions Solar panels work best in full sunlight, so you want to keep them free from obstructions that would cast shade on the panels. Check your build site for trees, chimneys, or anything else that could block sunlight from hitting your panels. Keep in mind that shadows get longer in the winter as the sun takes a lower arc across the sky. Make sure that your build site will be free from shade all year-round. If partial shade is unavoidable, the impact can be mitigated with micro-inverters or power optimizers. However, they won’t match the output of an array built with full exposure to sunlight.
Orientation Solar panels produce the most power when they face directly toward the sun, which takes a path in the sky that follows the Equator. So if you live in the Northern Hemisphere, you want to face your panels due South. In the Southern Hemisphere, face them North. As you select a build site, make sure you can face your panels in the right direction. If you don’t have a suitable space on your rooftop, consider a ground mount away from obstructions to get the most out of your panels.
System Voltage Solar batteries come in a variety of voltages, including 6V, 12V, 24V and 48V. We recommend a 48V DC battery bank simply because it’s the most efficient and cost-effective option available. At lower voltages, you will need to buy more electronics and invest in more cabling to handle the higher amperage from the system (the amperage is doubled every time the voltage is cut in half). In an off-grid residence, 48V is the better option. For best results, it is most common to use 6V batteries and wire them in series for a total of 48 volts.
Determine Your Energy Needs
There are three key factors to consider when sizing an off-grid system:
(“KWh” stands for kilowatt-hour, the standard measure of how much electricity your appliances consume while in use. You can find this rating on the appliance’s EnergyStar sheet.)
To start, make a list of each appliance’s wattage consumption. Then write down how many hours you plan to use each appliance on a daily basis. This information is necessary to move forward with the sizing process.
off-grid load calculator
We’ve got a handy off-grid load calculator to help you keep track of your appliance’s wattage consumption.
Important! 1,000 watts = 1 kilowatt. Be sure to convert watts to kilowatts before you make your kWh calculations, or your numbers will be off!
What is Your Peak Power Demand?
What are the electrical loads that you will need to run? Will they all run at the same time, or can you rotate the loads?
Your peak power demand is your total wattage usage when you are running all the electrical loads you need simultaneously. By staggering usage of major appliances at different times, you can reduce your peak power demand and bring system costs down.
Figure out how many appliances you expect to run at the same time, and add up their wattage consumption. The total is your peak power demand. Make note of this number, as we’ll be using it to figure out your inverter size.
What is your daily kWh usage?
Using the load evaluation worksheet you filled out, multiply the appliance wattage by the number of hours it will be in use each day. As an example, if you run a 1,500-watt dishwasher for 30 minutes each day:
1,500 watts x 0.5 hours = 750 watt-hours (Wh)
Remember to divide by 1000 to convert from watts to kilowatts.
750 Wh / 1000 = 0.75 kWh daily usage
Repeat this step for each appliance you will use, and tally them all up to get your daily kWh usage. Write that number in your notes.
What is your nightly kWh usage?
In the daytime, the power you use comes straight from your solar panels. When the sun goes down and panels are no longer generating power, the battery bank takes over and your appliances will run off of stored energy.
Using the same method as above, add up the appliances you’ll use at night and tally them here. Your fridge, TV, and smartphone charger are common appliances that run in the evening and overnight. Your inverter also has a self-consumption rating (the amount of power it takes to run the inverter) which should be accounted for.
Well-designed off-grid homes can use as little as 3-4 kWh per night, but yours may be higher if you want to run power-intensive appliances in the evening, like an HVAC system.
Tally up your nightly kWh usage and write the number down in your notes.
Off-Grid Battery Bank Sizing
With the above figures in hand, we’re finally ready to begin our system sizing calculations. We’ll start with the battery bank, which needs to be sized to accommodate both peak and continuous demand.
For the purpose of demonstration, we’ll walk through the math for a sample off-grid system with the following energy needs:
Full Description and 5 Riveting Benefits of an Off-Grid Solar System
It is no surprise you are on the search to understand, “What is an off-grid solar system?” Right now, off-grid power is an extremely “hot” topic (no pun intended, so hold the applause ) among the renewable energy community. So, naturally, you want to understand more of the innovative power behind off-grid solar.
This blog is going to spark your queries into full-fledged confidence on what all this off-grid talk is about and specifically answer, what is an off-grid solar system. Plus, how does off-grid solar system work, and divulge the benefits of an off-grid solar system.
Off-Grid Living = Off-Grid Solar.
Perhaps you are confused by the ambush of information on the web for an off-grid living when all the while you were hoping to understand off-grid solar. There are differences between the two, yet at the end of the day, they connect beautifully.
Let’s begin connecting those dots.
Prepare to be charged with newfound inspiration for off-grid solar power!
First, what is Off-Grid Living?
Off-Grid Living: Living independently without any public supplies of utilities such as water, heat, AC, electric, etc.
You might be planning to live or create a getaway zone for yourself where you don’t have to deal with society and avoid the system. It can be anything such as an RV, Cabin, or a two-story house with a small garden that is not dependent on the electricity grid.
Now, as a huge part of off-grid living, you will most likely need to get on the off-grid solar systems! Here is where you’ll get the idea of “off-grid-living” and how it is linked to the “off-grid solar” topic.
Second, What is Off-Grid Solar?
According to Energy Sage, the term off-grid can be defined as, …” living autonomously without reliance on a utility for power.”
Or as Merriam Webster puts it, “not connected to or served by publicly or privately managed utilities (such as electricity, gas, or water)”.
The Official Zonna Energy Off-Grid Solar Definition
Let’s cut to the chase with the official and simple Zonna Energy definition. Off-grid is functioning electrically without any connection to a mainline power supply.
Whoa! So, off-grid literally means no connection to your state or counties main electrical grid.
What is an Off-Grid Solar System?
An off-grid solar system permits electricity to be harnessed by solar panels and stored inside a battery without direct connection to the utility grid, providing an independent power supply to your home or business.
Basically, an off-grid solar system is a novel innovation which provides you independent energy harnessed by the sun. An off-grid solar system is made up of the following components.
Now that we answered, what is an off-grid solar system, lets dish out how off-grid solar energy systems actually work.
How Does Off-Grid Solar Work?
The ingenuity of an off-grid solar energy system is made-up of the efficiency of its components. A solar energy system’s solar panels, charge controllers, battery bank, and inverters all work together to provide your laptop or refrigerator energy, and this is how.
Off-grid solar energy systems work by…
- Solar Panels (PV array). Solar panels are set either on your rooftop or in an open yard or property space. The Sunlight is soaked up by the solar panels and transferred to the charge controllers.
- Charge Controllers. The charge controller is the “delivery man” between the solar panels, the inverters, and the battery bank. Charge controllers also act as a regulator, ensuring that the amount of power received through the solar panels does not overload the battery, instead keep the battery fully charged and top it off when needed. The charge controllers either deliver the energy directly as DC power to your lights or to the inverters to be converted into AC power for household appliances and all excess energy goes to the…
- Battery Bank. With the charge controllers feeding energy to the batteries, the battery bank acts as the heart of the off-grid solar system, as it stores up excess energy for cloudy days and nights, when needed it pumps electricity to the…
- Inverters. Lastly, inverters convert the DC (direct current) power into AC power which is passed on to be digested by your electronics or appliances as DC power and allows you to switch on the TV or fry up an egg.
Bam! Can you picture yourself eating that fried egg on a piece of toast with some sliced avocado? Reality check…that delicious sunny side up, was fried simply through the power of the sun. If that does not pull your self-sufficient cape out, get a load of the following benefits of an off-grid solar system!
What You Need to Know About Off-Grid Solar Systems
As you already know, the sun offers an abundant supply of energy for those who tap into its power supply.
And solar energy is becoming increasingly affordable and available across the U.S.
The industry continues to increase solar capacity, with installations skyrocketing by 43% per year and adding more than 19.2 gigawatts in 2020 alone.
At current capacity levels, solar energy could power nearly 18 million homes in America.
Most people who install solar panels tap into their district’s power grid, but as COVID has shown us, it’s possible to detach from the grid entirely.
With remote work available and more people seeking self-sufficiency, we can live in remote locations and be entirely energy independent with an off-grid solar system.
What Is an Off-Grid Solar System?
If you live off the grid, it implies that you are entirely autonomous.
However, you can incorporate certain aspects of off-grid living into a residential home without going all out.
With off-grid solar, you obtain your home’s power supply from the sun with the help of solar panels, batteries, and inverters.
You aren’t dependent upon your local utility company to provide your home’s electricity. But this isn’t the only thing that answers what off-grid vs. on-grid solar systems is.
Differences Between Off- and On-Grid Systems
When answering the question, “What is meant by off-grid solar systems?” it helps to examine the differences between on- and off-grid systems.
Looking at these differences provides a clearer idea about what an off-grid system entails:
Energy Access
- The main difference between the two systems is how reliant you are on your utility company.
- With an off-grid system, your setup is entirely independent. Sunlight and batteries are your only sources of power.
- On-grid setups are still hooked into the local grid, so if your system can’t generate enough electricity to operate your household — you pull energy from the utility grid.
Excess Energy Production
- Often, solar panels pull in more energy than is needed to supply your home with electricity.
- If you have an off-grid system, the excess energy produced is stored in a battery bank.
- When you aren’t connected to the grid, you need this extra energy to power your home on cloudy days and after dark. Your system needs to be big enough to capture more energy than you need when the sun is shining.
- With an on-grid system, the excess is usually sent to the grid.
- You’re given credit for the amount of excess energy your system produces, and you draw down on those credits when your system doesn’t supply you with enough electricity.
Power Outages
- If you live in an area where power outages occur due to excess heat or storms, you know what it’s like to go without electricity, fumbling in the dark until the grid is restored.
- With off-grid solar systems, these outages won’t impact you.
- Unfortunately, grid-linked systems are still affected by power outages because they’re required to have Rapid shutdown capabilities to ensure power line workers’ safety.
Electric Bills
- If you aren’t connected to the grid, you won’t receive an electric bill.
- On-grid system users still receive a bill from the power company.
- Usually, homeowners still incur nominal charges — even if their homes are 100% solar-powered — just to connect to the grid.
The Benefits of Off-Grid Solar
Solar energy is great for your wallet, perfect for your off-grid energy needs, and good for the environment.
Currently, electricity generation is responsible for 28% of the United States’ greenhouse gas emissions, and 82% are carbon dioxide gases.
Solar significantly reduces your environmental footprint by supplying you with an emissions-free and clean energy source.
Installing an off-grid solar system requires an upfront investment, but it saves you money on your electric bill over the long term.
The amount you save depends on factors, such as where you live, how much sunlight hits your solar panels, and what your local utility company charges for electricity.
Most people find that they can save anywhere from 10,000 to 30,000 over their solar system’s life cycle.
How Does an Off-Grid Solar System Work?
Aside from the solar panels, the most critical component to a fully functioning off-grid solar system is the battery bank.
Since the home’s electricity is entirely independent of a utility company, the autonomous system relies on stored power when the solar panels cannot take in enough solar energy to supply household needs.
You need sufficient solar panels to power your home in an off-grid system while also sending excess energy to the batteries.
After the sun goes down or on cloudy days, you’ll draw power from the batteries.
So, you also need a large enough battery bank to store the energy you need to operate electric appliances, lights, and technology.
What Is Needed for an Off-Grid Solar System?
Let’s look at an off-grid solar power system in terms of the individual components you need to make it work.
These systems require these four primary components to function:
#1: Solar Panels
Most off-grid systems use monocrystalline solar panels.
These provide more efficient power than the polycrystalline panels, which is essential when you are off-grid.
The number of panels you need depends on what the electricity load and usage are in your home.
#2: Charge Controller
The charge controller is critical in keeping your batteries sufficiently charged without overloading them.
The controller adjusts the flow of energy between the panels and the batteries.
A maximum power point tracking controller is more reliable than a pulse width modulation controller in preventing battery overload.
#3: Inverter
An inverter is necessary to convert the DC power stored in the batteries into your home’s AC power.
You need to make sure you get one large enough to handle the peak electricity load in your home.
#4: Batteries
Batteries are essential in an off-grid system.
You’ll need enough of them to store a sufficient amount of electricity.
The most efficient and safest type of battery for off-grid solar is the lithium-ion phosphate battery. They also allow you to expand your battery bank without compromising its integrity.
Where Can You Get Everything You Need for Off-Grid Solar?
Unbound Solar has everything you need for your home’s off-grid solar system. We offer complete kits to meet your needs and your situation.
These kits come pre-wired, making installation a breeze.
We also have all of the individual components you’ll need to build the off-grid system you desire.
Together, we will handle all of your installation labor and requirements with free lifetime support.
We’re ready to help you achieve energy independence on your terms!