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

Run your own Solar Energy System! 5 Meters display charging, power, voltage, & more. Watch the power change as you turn appliances on/off.

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

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  System Sizing Estimator
  Battery Bank Designer
  Wire Size Calculator
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Advanced Tutorials: Solar Radiation
Solar Radiation : Sunshine across the United States
The map below shows the yearly average of the approximate daily sunshine in KiloWattHours per square meter of flat panel surface area facing the equator and tilted at an angle equal to your latitude. Translation: Each zone shows the average number of hours of sunshine per day. A typical solar panel in the range of 75 to 85 watts is about a square meter. So if you have six 80 watt solar panels in the 5.0-5.5 zone you can figure 6 panels times 80 watts times 5 hours equals 2400 watthours per day or 2.4 KiloWatts per day. Of course, this is an average and you will get more power in the summer than the winter, obviously.
This chart shows the distribution of Solar Radiation (sunshine) across the United States
Another way to calculate this is using AmpHours. An 80 watt panel at 12 volts will produce about 5.5 amps under strong sunlight. If you have 5 hours of sun times 5.5 amps you will get 27.5 AmpHours per day. Using the example of 6 solar panels, that becomes 6 times 27.5 or 165 AmpHours per day.
A practical everyday example using AmpHours instead of WattHours
Ok, you ask, how is all of this useful? Well, when calculating system size for both the number of solar panels and the number of batteries needed it is customary to use WattHours. However, in practice, when your system is operating, your meters/monitors will give you AmpHour information. For example, if your charge controller is showing that by midday you have already received 85 AmpHours of energy and the only thing running is your refrigerator (using 40 AmpHours per day), then you can quickly see that you are gaining and your batteries are charging not discharging. This is immediately obvious without having to convert everything to watts and WattHours.

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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