Free Sun Power shining on Solar panels generates free energy by converting sunlight to electricity with no moving parts, zero emissions, and no maintenance Free tutorials, interactive online Design Tools and a Solar Power Simulator at

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Details of the Solar Energy System used in this small, energy efficient, earth sheltered home.

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Easy to follow Step by Step Guide to setting up a solar energy system
Frequently Asked Questions
What is the minimum equipment I'll need?
The basic components required to produce electricity from the sun are : One or more Solar Panels, a Charger Controller, a Power Inverter, and of course, Batteries.
Take a look at a simple animation of all these components working together. This will give you an overview of the minimum equipment needed for a solar powered alternative energy system.    <details>
Solar Panels   <Back to Top>
How many Solar Panels will I need? This will depend on the amount of energy in watts that your appliances use. To get an idea of the wattage you'll need, use our System Sizing Estimator.
How do I mount my Solar Panels? The most simple mount is a ground based frame angled toward the sun. A step up is a raised mount that has an adjustable angle to allow for the changing angle of the sun in the sky through-out the year. The most efficient (and most expensive) is a tracking mount that follows the sun in it's arc across the sky each day.
How much do Solar Panels cost & what is their expected LifeSpan? Depending on size, expect to pay between $4.00 and $5.00 per watt. A typical 100 watt solar panel will cost about $400 to $450. The good new is they are quite durable & you can expect 25 years or more of service.    <details>
Is it true that a Solar Panel won't produce as much energy as it took to manufacture it? Many studies have been done on this subject and the answer is NO. It is a complete myth that a solar panel will never produce as much energy over its useful life to equal the energy that it took to manufacture it. This question may have had some truth to it 30 years ago, but not today. That's just the electric company talking...
Charge Controllers   <Back to Top>
Why do I need a Charge Controller?  A charge controller regulates the charge on the batteries, giving full power when necessary and reducing the charge as the batteries require less. This is important for maintaining the health of the batteries.
What is a PWM charge controller?  PWM stands for Pulse Width Modulation and is basically a 3 stage charging cycle type controller. Most decent charge controllers use this technique.
What is a MPPT charge controller?  MPPT stands for Maximum Power Point Tracking. This is a newer type controller that not only provides multi-stage charging, but it also delivers more power to the batteries by matching the battery voltage to the solar panel voltage. This makes them more efficient especially in varying levels of sunshine. They also cost a little more.    <details>
Power Inverters   <Back to Top>
Do I need a Power Inverter? Actually, no. This is the only component of a solar energy system that is not absolutely required. However, if you don't use one, you will not have 120 volts AC and will have use battery power alone. This might be acceptable in a small RV or cabin, but most people want to use normal AC appliances.
What's the difference between 12, 24, and 48 volt inverters?  This refers to the input voltage from the battery bank. The main consideration is that at higher voltages the current is less so that you can use smaller wires between your solar panel array and your battery bank. Of course, when you decide on a system voltage, the Solar Panels, Inverter, and Battery Bank all need to use the same voltage. More detailed information on voltage & current is explained in the tutorial on Power & Watts.
What is a Grid Tie inverter?  If you are connected to normal Utility company power and just want to add some Free Sun Power electricity to reduce your electric bill and you do not need a independent system, it is possible that a Grid Tie inverter will suit your needs. With a Grid Tie inverter, whatever electricity that your solar panels produce will reduce the amount supplied by the power company, in effect lowering your bill. For this setup a large battery bank to store the power for later use is not needed. Unless you have frequent power company outages, you will not need any batteries at all.
What's the difference between a true sine wave inverter and a modified sine wave inverter?  The AC sine wave of a true sine wave inverter is just as good as the utility company's AC power. A modified sine wave inverter is not as close, but is still quite satisfactory in most cases. Certain motor control circuits don't like the modified wave. Modified sine wave inverters are also much less expensive.   <details>
Storage Batteries   <Back to Top>
What is meant by Flooded batteries? Flooded batteries have those little caps on top and you must add water (distilled) to them from time to time as the charging process boils off some of the water as hydrogen gas. They should be installed in vented boxes and not used indoors or near spark or flame.
What is a sealed battery? Not to be confused with maintenance free, a sealed battery has no service caps and water is never added. They also do not out gas during the charging process and are safe to use indoors. This usually means that the temperature of the battery will be more constant which translates into more efficient operation.
Should I use Flooded or Sealed batteries? While you can safely use sealed types indoors, they are more expensive than flooded types. So, cost factors and where you plan to locate the batteries are the main deciding factors.    <details>
AC Generators   <Back to Top>
Why should I have a Generator if I have Solar Panels? When supplying your own power, it's a good idea to have back-up power for 2 reasons. Number one is that in the winter (depending on your location) you will often have too many days of low sunshine to supply all your electric needs from the solar panels alone. Reason number 2 is that you will probably have some equipment that uses large amounts of power but is only needed some of the time. (say filling a water tank with a large pump)
How long does the generator need to run? During bad weather, you will need to supply the bulk of your battery charging with the generator. For a medium sized system, with no sunshine at all, an hour per day will usually provide enough of a charge for the batteries. A large system may require up to 2 hours. If you're running the generator for more than 2 hours per day, you most likely have sized your battery bank too small. See our System Sizing Estimator for more info on this subject.
What size Generator should I use & what do they cost? Generally speaking, except for very small or very large systems, a 5000 watt generator should do nicely. These vary in price, but a basic model will run around $500 to $700. <details>
Correct Cables & Wire sizes   <Back to Top>
Why is wire size so important? In order to obtain maximum energy transfer from your solar panels, the wires running to your equipment center need to be large enough too carry the current. Also, if they are too small, it is possible they could overheat & even catch fire. Just like water in a pipe, if the pipe is too small, then not enough water can pass through it. And, if you try to force the water through with more pressure, the pipe will begin leaking from the excess pressure just like the wire will begin to overheat with too much current passing through it. See our Wire Size Calculator to find the proper size wires for your system.
What about the rest of the system? The wires between the Charge Controller and the Batteries can be the same size as the wires from the Solar Panels. However, all the batteries and the inverter need to be connected with very large cables. These cables will usually be 2/0 or 4/0 gauge cables like the large battery cables in cars. The size of your battery bank and inverter will determine the minimum size and should be covered in detail in the instructions that come with your inverter.   <details>

Design your system quickly with our Interactive Design Tools
(Note : These design tools require javascript to be turned on in your browser)
* Check out our easy point & click System Sizing Estimator to quickly & easily calculate the number of solar panels and storage batteries you'll need for a wide range of system sizes.
* Our Battery Bank Design Tool will take the confusion out of wiring up your battery bank. Use 2, 4, 6, or 12 volt batteries to build a system voltage of 12, 24, or 48 volts using series and parallel wiring with just 4 clicks. Battery bank capacities from 300 AmpHours to over 4000 AmpHours are displayed graphically so you can see exactly how to wire the batteries together.
* This Wire Size Calculator will allow you to quickly find the correct wire size in AWG (American Wire Gauge) based on the distance to your solar panel array & the amount of amperage your panels put out. No math required!

New Feature!  Check out our new feature Solar Projects where you can build easy, do-it-yourself projects for your solar power system to save money and have fun doing it!

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