DIY Solar Power System
Residential solar photovoltaic systems supply electricity directly to a home using solar panels mounted on a roof or in an open area, such as the garden. These types of solar systems are basically the same type of system installed by pioneering homeowners back in the early days of solar development, the difference today however, is that installing your own DIY Solar Power System has never been easier as today, solar panels are much more energy efficient, lighter, compact and also a lot cheaper.
The type of electricity produced by solar panel is called DC, or direct current, the same type that batteries use. However, most standard household appliances and lighting fixtures operate on higher AC, or alternating current, electricity.
Therefore, any photovoltaic solar system must include some form of inverter to convert the low level DC power (typically 12 volts) from the solar panels into the higher level AC power (typically 240 volts) for use around the home. Household appliances operate just as well on solar generated DC power as they do on mains generated AC power supplied by the utility company.
Before you can start designing your very own DIY solar power system or ready made solar kit, you need to make a few decisions first. Such as: do I want a grid-connected or an off-grid connected system, do I want or need storage batteries as part of my system, and what are my energy requirements and consumption, etc.
Photovoltaic (PV) systems may only cost a fraction of what they did say 25 or 30 years ago, but they are still quite expensive to buy and install, so making some decisions and having a clear idea first before you start will same you money in the long term.
Whether you choose a whole-house grid-connected system or a self contained off-grid system with battery storage, you may need an array of solar panels producing several thousand solar watts of power just to meet your current household needs (depending on your house size, its energy efficiency, teenagers and so on). So before you start designing a solar power kit, you will need to calculate the total power requirements of all of your homes electrical items.
Calculating your Energy Requirements
The actual electricity generated by a simple DIY Solar Power System is basically a function of its panel size (either individually or as an array), its solar efficiency, positioning, amount of sun exposure plus a variety of other such factors, so it is important that when you are designing a DIY solar power kit that its size will generate enough electricity to cover your average household’s electricity usage throughout the year.
The electrical power rating of a typical appliance is generally given in Watts which you can find by either looking at the appliances identification sticky label or by the products data given in the user manual. Some manufacturers give the appliances wattage value in volt-amps, for example 200VA (two hundred volt-amps). This volt-amps rating is more or less the same as that given in Watts because Watts is just voltage times current, that is volts times amperes, or VA which is shortened to just VA.
The appliances daily energy consumption is simply calculated as the VA or Wattage rating multiplied by the number of hours per day it is switched on or being used (watts times hours or Whr). So for example if our 200VA (or Watts) appliance is used for 5 hours during a 24 hour period, then the total consumption of energy would be 200VA multiplied by 5 hours which gives 1,000 watt-hours or 1 kWh (one kilo-watt hours), as 1,000 watts is equal to 1 kilo-watt (kW).
Likewise if you had a 60W lamp switched on at night for 3 hours, its energy consumption would be 60 multiplied by 3 which equals 180Whr (one hundred and eighty watt hours), or 0.18kWhr.
The advantage of using watts is that wattage always represents the electrical power of an appliance regardless of the supply voltage. Once done, repeat the above calculations for all the electrical items you want to power from your diy solar power kit and add them up.
Note that unless you intend to have a full-house grid-connected solar system it is beneficial when designing a solar power kit to have a mixture of both low voltage components such as 12 volt or 24 volt lamps, batteries and appliances, etc as well as mains voltage connected items just in case the mains inverter or circuit becomes faulty.
Building a Solar Powered Workshop
Finally, the important thing to remember when designing a diy solar system is to not only determine exactly what it is you will be powering, but can you reduce your energy needs. Because one watt of energy saved in the home, is one watt of energy that needs to be generated by solar, and if you manage to save over 200 watts in the home, that’s one less solar panel to buy and install.
Storing the Solar Energy in Batteries
Once you know how much electrical energy you are going to consume each day you can start thinking about ways of storing enough of it, because without storage you would only have power available during the day when the sun was shining. Luckily for us, long ago some bright spark invented the storage battery (actually French scientist Georges Leclanché in 1866) which allows us to do just that. the downside is that batteries add cost and complexity to any DIY solar power system, so choosing the right battery is also very important.
Different videos on YouTube and websites on Google shows us that it is possible to make a diy battery with just a lemon, a single copper coin and a galvanised nail, but obviously one lemon wouldn’t produce enough power to light a single LED (but apparently 4 or more will!). So in order to have sufficient power for your TV, lights and appliances around the home, we need something a little more advanced such as the 12V 100Ah AGM UB121000 deep cycle battery.
Modern solar kit batteries are available in a variety of shapes and sizes, ranging from just a few amp-hours (Ah) to many thousands capable of supplying huge amounts of electrical power. However, solar storage batteries are not the same in type or construction as regular car type cranking batteries.
These batteries should not be used when designing a DIY solar power system because these types of cranking batteries cannot be fully discharged and recharged continually without suffering from internal damage. However, they can still be charged using a photovoltaic panel.
Solar storage batteries are considered to be deep cycle lead acid types with have much thicker internal plates that can withstand many deep discharging cycles, although you shouldn’t really deep cycle them very often. When used as part of an alternative energy systems, deep cycle batteries will have a reasonably long working life if maintained and looked after.
RV or Marine type deep cycle batteries are basically classed as recreational batteries used in boats, caravans and camper vans. They are suitable for most small sized DIY solar power or lighting kits, and are available in 6, 12 and 24 volt sizes. Another very popular battery for small DIY solar systems is the golf cart battery. These are slightly more expensive than the recreational battery but are a good choice for a small solar system on a budget.
Heavier industrial type deep cycle lead acid batteries are very common in a typical off-grid system because of their physical size and power rating. Lead acid batteries exist in three main types: flooded lead acid, AGM (Absorbed Glass Mat) or sealed GEL batteries. Sealed AGM and GEL batteries have the advantage that they do not release as much gas (if any) into the room when they are charging.
All batteries store DC power as it’s not possible to store AC power in batteries. Solar storage batteries are rated in ampere-hours or Ah and generally come in multiples of 2 volt cells, so 6, 12 and 24 volt batteries are the most common.
We said previously that we use Watts (that is volts multiplied by amperes) to measure the power requirements of a solar system. Since batteries are rated in amp-hours (Ah), we need to calculate how much electrical power in Watts this equates to. So a typical 12 volt battery rated at 80 Amp-hours would be capable of delivering 960 Watt-hours (Wh) of power.
on grid solar power system | How to install solar power system for home | solar system
A DIY Solar Power System Battery Charging
All types of rechargeable battery can be charged-up using solar panels, wind turbines or a mains connected charger. While it is possible to charge a 12 volt battery directly from a 12V solar panel without regulating or controlling the amount of charging current it isn’t the best way of doing it.
To continually charge deep cycle storage batteries in a better and controlled way you will need a some form of charge controller. Charge controllers deliver the right amount of power from the solar panel to the battery in a precise and controlled way and are an important part of any well designed DIY solar power kit.
Keeping the deep cycle batteries of your solar power kit full of charge and healthy is also important because they will last a long time if you look after them giving you a return on your investment. Overcharging and/or undercharging a battery will eventually damage it, so keeping batteries healthy means charging them fully, regularly and in a controlled way.
Of course there’s a huge range of charge controllers available to choose from a few Dollars or Euro to several hundred. The more expensive models have built-in digital displays which allows you to monitor and see exactly what’s going on in your system. The charge controllers here is an excellent high quality example and would control a system well, but choose one that suits not only your system but your budget.
Calculate the Amount of Battery Storage You Need
Now that you know how much power you need, you need to figure out how many batteries you need to store it.
- Think about the weather patterns in your area. How frequently do you get multiple sunless or low-sun days in a row? Your batteries need to be able to get you by during periods when your solar panels are producing well below their maximum. Do you need only enough storage for a day or two, or do you need to have enough batteries to store three or four days (or more) worth of power?
- Do you have another power source, like a generator or turbine, that can kick in in a pinch?
- Will you be storing the batteries in an insulated room or will they be in a cold location?
Batteries are rated for storage at around 77°F (25°C). The colder the room they live in, the less efficient they are and the bigger the battery bank you’ll need – over 50% bigger for below freezing! Each of these answers affects the size – and therefore the cost – of your battery bank.
What voltage battery bank will you use – 12V, 24V, or 48V? Generally, the larger the system, the higher voltage battery bank; this keeps the number of parallel strings to a minimum and reduces the amount of current between the battery bank and the inverter. If you are planning a small system and simply want to be able to charge your cell phone and power 12V DC appliances in your RV, then a 12V battery bank makes sense. But if you need to power much over 2000 Watts at a time, you’ll want to consider 24 volt and 48 volt systems. Besides reducing how many parallel strings of batteries you’ll have, it’ll allow you to use thinner and less expensive copper cabling between the batteries and the inverter. Most full-time off-grid homes are best off with a 48V system.
So how many batteries do you need for your off-grid solar system? Use our off-grid calculator to calculate what size battery bank you need based on your answers to the questions above.
Calculate the Number of Solar Panels Needed for your Location and Time of Year
The second half of our off-grid calculator can help you figure out how many solar panels you’ll need for your solar system. After discovering how much energy you need to make per day from our load calculator, you’ll need to tell it how much sunshine you’ll have to harvest from. This available energy from the sun for a given location is referred to as that location’s “sun-hours.”
The number of sun-hours at a location is not the number of hours of daylight at the location. It is how many hours 1000 Watts worth of solar radiation strikes a square meter of surface area at the location over the course of a day. Obviously, the sun isn’t as bright at 8AM as it is at noon, so an hour of morning sun may be counted as half an hour, whereas the hour from noon to 1PM would be a full hour. And unless you live near the equator, you do not have the same number of hours of sunlight in the winter as you do in the summer.
When designing an off-grid solar system – especially one that will be counted on to provide your electricity day in and day out, be conservative. Take the worst case scenario of sun-hours for your area by using the season with the least amount of sunshine during the period in which you’ll be using the system (i.e. winter if your system will be powering a full-time residence). This way, you won’t end up short on solar energy for part of the year. If your system will be used for a summer camp or seasonal vacation cabin, you don’t need to plan for winter, but if it is a year-round home or a hunting cabin, you need to use the number of sun-hours that corresponds to winter.
Select a Solar Charge Controller
Alright, so we have batteries and we have solar, now we need a way to manage putting the power from the solar into the batteries. An extremely rough calculation to figure out what size solar charge controller you need is to take the Watts from the solar and divide it by the battery bank voltage. Add another 25% for a safety factor.
But there’s a bit more to consider with selecting a charge controller. Charge controllers are available with two major types of technologies, PWM and MPPT. In short, if the voltage of the solar panel array matches the voltage of the battery bank, you can use a PWM charge controller. So if you’re using a 12V panel and a 12V battery bank, you can use a PWM. If your solar panel voltage is different form the battery bank, and can’t be wired in series to make it match, you need to use an MPPT charge controller. If you have a 20V solar panel and you have a 12V battery bank, you need to use MPPT charge controller. If you’re doing a whole-home system, chances are very high that your best bet is a 48V battery bank and an MPPT charge controller (but we can help you confirm this if you want to give us a call at 877-878-4060 and talk through your system plans).
Step 2: Battery Selection
The batteries I use for my solar system
Top view of the batteries
The output from the solar panel is dc power. This power is generated during day time only. So if you want to run a dc load during day time then it seems to be very easy. But doing this is not a good decision because…
- Most of the appliances need a constant rated voltage to run efficiently. Solar panel voltage is not constant, it varies according to the sun light.
- If you want to run the appliances during the night then it is impossible.
The above problem is solved by using a battery to store the solar power during the day and use it according to your choice. It will provide constant source of stable, reliable power.
There are various kind of batteries. Car and bike batteries are designed for supplying short bursts of high current and then be recharged and are not designed for a deep discharge. But the solar battery is a deep-cycle lead-acid battery that allows for partial discharge and allows for deep slow discharge. Lead acid tubular batteries are perfect for a solar system.
Ni-MH batteries and Li-Ion batteries are also used many small power application.
Note: Before going to choose the components decide your system voltage, 12/24 V or 48 V. The higher the voltage, the lesser the current and the lesser the copper loss will be in the conductor. This will also reduce your conductor size. Most of the small home solar systems will have 12 V or 24 V.
In this project I’ve selected the 12 V system.
Rating of Battery:
Batteries capacity are rated in term of Ampere Hour.
Watt Hour = Voltage (Volts) x Current (Amperes) x Time (Hours)
Battery Voltage = 12V ( as our system is 12V)
Battery capacity = Load / Voltage = 365/12 = 30.42 Ah
But batteries are not 100% efficient, assuming 80% efficiency
Capacity = 30.42/0.8 = 38.02 Ah
By taking some margin you can select a 40Ah deep cycle lead acid battery.
Step 3: Solar Panel Selection
A big 255W solar panel @ 24V
Solar panel ratings for the 255W solar panel
The Solar Panel converts the sunlight into electricity as direct current (DC). These panels are typically categorized as mono crystalline or poly crystalline. Mono crystalline are costlier and more efficient than poly crystalline panels.
Solar panels are generally rated under standard test conditions (STC): irradiance of 1,000 W/m², solar spectrum of AM 1.5 and module temperature at 25°C.
Rating of Solar Panel:
The solar panel size should be selected in such way that it will charge the battery fully in one sunny day.
During the 12hr day time the sunlight is not uniform, and it also differ according to your location on the globe. So we can assume 4 hours of effective sunlight which will generate the rated power.
So total power output of Panels = 12V x 40Ah = 480Wh
Power to be generated per hour = 480 / 4 = 120W
By taking some margin you can choose a 125 W, 12v solar panel.
Step 4: Charge Controller Selection
An example charge controller
Another charge controller
A solar charge controller is a device which is placed between a solar panel and a battery. It regulates the voltage and current coming from your solar panels. It is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar panel rises, the charge controller regulates the charge to the batteries preventing any over charging.
Usually, the solar power systems uses 12 volt batteries, however solar panels can deliver far more voltage than is required to charge the batteries.
By, in essence, converting the excess voltage into amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This allows the solar power system to operate optimally at all times.
Types of Charge Controllers:
Try to avoid the ON/OFF charge controller as it is the least efficient.
Among the 3 charge controllers MPPT have the highest efficiency but it is also costly. So you can use either PWM or MPPT.
Rating of Charge Controller:
Since our system is rated at 12V, the charge controller is also 12V.
Current rating = Power output of Panels / Voltage = 125 W / 12V = 10.4 A
So choose a Charge Controller of 12 V and more than 10.4 A.
If you like to reduce your system cost you can make your own PWM charge controller. For step by step instructions you can see my instructable on building a PWM Charge Controller.
You may also like my new 3.0 design of an Arduino MPPT Solar Charge Controller.
Building solar panels: how to make your own solar system
Making your own solar panel is a time-consuming process and requires some electrical skills. However, it can also be very rewarding – learning to build your own PV panel is a great way to understand how solar electricity is generated.
Before you can build your own solar panels, you first need to understand how solar cells generate electricity. The vast majority of solar panels in use today are made of crystalline silicon wafers, which typically measure six inches square. When the sun shines on those wafers, the electrons in them start to move. This flow of electrons is an electrical current.
A single full-sized solar panel, like the kind used in rooftop solar power systems, will have 60 silicon wafers. You can also make smaller panels if your electricity needs are low. Once you’ve bought individual solar cells (they can be purchased online), the basic process for building your own solar panel goes like this:
- Prepare the backing for your panel. Many DIY solar panel builders use a wooden board as the base for their solar cells. You’ll need to drill holes in the board so that the wires for each cell can pass through.
- Wire your solar cells together. This requires some experience with electrical work. Use a soldering iron to attach wire to the solar cells and then link each of the cells together.
- Attach cells to your backing. If possible, affix each solar cell to the backing individually. This makes it easier to replace a single cell in the event that becomes damaged or is not operating properly.
At this point you have a functional solar panel that can produce electricity when the sun shines. However, a solar panel by itself is not useful. If you are trying to generate electricity to power devices in your home, you need to pair your panel with an inverter that will turn direct current (DC) power from the sun into the alternating current (AC) power used in most modern electronic devices.
For a standalone off-grid system, you will also need to include a battery pack and charge controller in your DIY solar setup. The battery pack serves to store excess energy, and the charge controller manages the amount of electricity that flows through the battery.
If you want to build a solar panel system that will power your home, the process is significantly more complicated. A standard grid-connected solar PV system that can power your home will have around 20 solar panels, each of which will need to be wired together and mounted to your roof (or in an unshaded ground location on your property). Most importantly, a qualified electrician has to confirm your system has been built correctly before your utility will allow you to connect your panels to the electric grid.
Build your own solar panel system, or work with an installer
Whether you DIY your own solar panel system with a solar kit or work with an experienced solar installer depends on why you want to install solar.
Solar panels are portable and convenient for a variety of off-grid uses. You don’t even have to build your own solar panels if you don’t want to – there are inexpensive solar panel kits for sale that include each of the components you’ll need for a DIY solar installation. Building your own solar panel system is a good option if you want to construct a small off-grid system to power a cabin, RV, boat, or tiny home.
For a whole-home solar panel system, work with a solar installer
When it comes to installing a full-scale solar power system on your property, working with a solar installer with significant experience can save you both time and money in the long run. Some of the top solar companies have been installing solar energy systems for decades – experience that no amount of online research or DIY guides can replicate. Your solar installer can also help you find the financial incentives available in your area and complete the permits and applications necessary to get your solar energy system up and running.
To get a sense for how much you can save by installing a solar panel system for your home, review an instant solar estimate from EnergySage’s Solar Calculator. If you’re debating between building your own solar power system and working with an installer, get a few quotes from local solar companies to see what it would cost. You can easily compare options from qualified installers in your area for free by joining the EnergySage Solar Marketplace.
The core accretion model
Approximately 4.6 billion years ago, the solar system was a Cloud of dust and gas known as a solar nebula. Gravity collapsed the material in on itself as it began to spin, forming the sun in the center of the nebula.
With the rise of the sun, the remaining material began to clump together. Small particles drew together, bound by the force of gravity, into larger particles, according to the core accretion model. The solar wind swept away lighter elements, such as hydrogen and helium, from the closer regions, leaving only heavy, rocky materials to create terrestrial worlds. But farther away, the solar winds had less impact on lighter elements, allowing them to coalesce into gas giants. In this way, asteroids, comets, planets and moons were created.
Some exoplanet observations seem to confirm core accretion as the dominant formation process. Stars with more metals — a term astronomers use for elements other than hydrogen and helium — in their cores have more giant planets than their metal-poor cousins. According to NASA, core accretion suggests that small, rocky worlds should be more common than the large gas giants.
The 2005 discovery of a giant planet with a massive core orbiting the sun-like star HD 149026 is an example of an exoplanet that helped strengthen the case for core accretion. The planet’s core is about 70 times more massive than Earth, scientists found; they believe that is too large to have formed from a collapsing Cloud, according to a NASA statement about the research.
Pebble accretion
The biggest challenge to core accretion is time — building massive gas giants fast enough to grab the lighter components of their atmosphere. Research published in 2015 probed how smaller, pebble-size objects fused together to build giant planets up to 1,000 times faster than earlier studies.
This is the first model that we know about that you start out with a pretty simple structure for the solar nebula from which planets form, and end up with the giant-planet system that we see, study lead author Harold Levison, an astronomer at SwRI, told Space.com at the time.
In 2012, researchers Michiel Lambrechts and Anders Johansen of Lund University in Sweden proposed that tiny rubble, once written off, held the key to rapidly building giant planets. They showed that the leftover pebbles from this formation process, which previously were thought to be unimportant, could actually be a huge solution to the planet-forming problem, Levison said.
In simulations that Levison and his team developed, larger objects acted like bullies, snatching away pebbles from the mid-size masses to grow at a far faster rate. The bigger guy basically bullies the smaller one so they can eat all the pebbles themselves, and they can continue to grow up to form the cores of the giant planets, study co-author Katherine Kretke, also from SwRI, told Space.com.
The disk instability model
Other models struggle to explain the formation of the gas giants. According to core accretion models, the process would take several million years, longer than the light gases were available in the early solar system.
Giant planets form really fast, in a few million years, Kevin Walsh, a researcher at the Southwest Research Institute (SwRI) in Boulder, Colorado, told Space.com. That creates a time limit because the gas disk around the sun only lasts 4 to 5 million years.
A relatively new theory called disk instability addresses this challenge. In the disk instability model of planet formation, clumps of dust and gas are bound together early in the life of the solar system. Over time, these clumps slowly compact into a giant planet.
Planets can form in this way in as little as 1,000 years, the models suggest, allowing them to trap the rapidly vanishing lighter gases. They also quickly reach an orbit-stabilizing mass that keeps them from death-marching into the sun.
As scientists continue to study planets inside of the solar system, as well as around other stars, they will better understand how gas giants formed.
Planets on the move
Originally, scientists thought that planets formed in their current locations in the solar system. But the discovery of exoplanets shook things up, revealing that at least some of the most massive worlds could migrate through their neighborhoods.
In 2005, a trio of papers published in the journal Nature outlined an idea the researchers called the Nice model, after the city in France where they first discussed it. This model proposes that in the early days of the solar system, the giant planets were bound in near-circular orbits much more compact than they are today. A large disk of rocks and ices surrounded them, stretching out to about 35 times the Earth-sun distance, just beyond Neptune’s present orbit.
As the planets interacted with smaller bodies, they scattered most of these objects toward the sun. The process caused the massive planets to trade energy with the smaller objects, sending the Saturn, Neptune and Uranus farther out into the solar system. Eventually the small objects reached Jupiter, which sent them flying to the edge of the solar system or completely out of it.
Movement between Jupiter and Saturn drove Uranus and Neptune into even more eccentric orbits, sending the pair through the remaining disk of ices. Some of the material was flung inward, where it crashed into the terrestrial planets during the Late Heavy Bombardment. Other material was hurled outward, creating the Kuiper Belt.
As they moved slowly outward, Neptune and Uranus traded places. Eventually, interactions with the remaining debris caused the pair to settle into more circular paths as they reached their current distance from the sun.
Along the way, our solar system may have lost members: It’s possible that one or even two other giant planets were kicked out of the neighborhood by all this movement. Astronomer David Nesvorny of SwRI has modeled the early solar system in search of clues that could lead toward understanding its early history.
In the early days, the solar system was very different, with many more planets, perhaps as massive as Neptune, forming and being scattered to different places, Nesvorny told Space.com
Where’s the water?
Even after the planets had formed, the solar system itself wasn’t quite recognizable. Earth stands out from the planets because of its high water content, which many scientists suspect contributed to the evolution of life.
But the planet’s current location was too warm for it to collect water in the early solar system, suggesting that the life-giving liquid may have been delivered after Earth formed.
Just one hitch: scientists still don’t know where that water might have come from. Originally, researchers suspected comets carried it to Earth, but several missions, including six that flew by Halley’s comet in the 1980s and the European Space Agency’s more recent Rosetta spacecraft, revealed that the composition of the icy material from the outskirts of the solar system didn’t quite match Earth’s.
The asteroid belt is another potential source of water. Several meteorites have shown evidence of alteration, changes made early in their lifetimes that hint that water in some form interacted with their surface. Impacts from meteorites could be another source of water for the planet.
Recently, some scientists have even challenged the notion that the early Earth was too hot to collect water. They argue that, if the planet formed fast enough, it could have collected the necessary water from icy grains before they evaporated.
Whatever process brought water to Earth likely did so to Venus and Mars as well. But rising temperatures on Venus and a thinning atmosphere on Mars kept these worlds from retaining their water, resulting in the dry planets we know today.
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Nola Taylor Tillman is a contributing writer for Space.com. She loves all things space and astronomy-related, and enjoys the opportunity to learn more. She has a Bachelor’s degree in English and Astrophysics from Agnes Scott college and served as an intern at Sky Telescope magazine. In her free time, she homeschools her four children. Follow her on at @NolaTRedd
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