SolarDesignTools provides free interactive online design tools for Electric Solar Power energy systems. This includes determining the required number of solar panels, how many batteries will be needed, calculating wire sizes, a solar radiation chart, example system pictorials, and more.
Try this example of an interactive electric Solar Power Simulator to see how Solar Energy systems work.

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Storage Batteries

Storage Batteries
If you want a stand alone system that does not require the existing electrical grid, you will have to use storage batteries. The batteries will charge up and store power when there is sunshine and deliver it later. A DC to AC power inverter is required to convert the 12 Volt DC battery voltage to usable 120 Volt AC power which most appliances use. A small cabin might get away with all 12 Volt DC equipment, but a normal house will need 120 Volt AC power to run modern appliances, lighting, computers, etc.
Batteries come in many different configurations. The actual physical size is a combination of the voltage and the power capacity of the battery usually expressed as AmpHours. The overall voltage of the battery bank needs to match the charging voltage from the solar panels. For example: If you used four 6 Volt batteries wired in series, this would give you a 24 Volt battery bank. There are many combinations of total voltage and total power (capacity). The Battery Bank Designer will show you the most common variations.
There are two basic categories or types of batteries. Flooded and Sealed. A flooded battery has filler caps and water must be added periodically to maintain the electrolyte level. Flooded batteries are probably the most popular because they are less expensive. The main problem with these batteries, though, is they emit hydrogen gas during the charging process causing corrosion of the cable connectors and other metal parts. Also, since hydrogen gas is explosive, venting is required.
Sealed batteries eliminate all these problems. They do not require water, do not outgas hydrogen, do not cause corrosion, and no venting is required. I believe the extra cost is well justified. The first time you have to shut your system down, remove all the cables/connectors, and repair/clean or replace them entirely, I think you will agree. AGM (absorbed glass mat) batteries are a popular sealed battery. While both types use lead/acid chemistry, the sealed batteries use a paste rather than liquid. Another plus for AGM sealed batteries is that you can keep them indoors where they will stay warmer since they don't outgas. By the way, most battery specifications are based on a 77 degree temperature. If they are kept in a vented box outside, their performance will suffer dramatically when they are cold.

Do not confuse sealed batteries with maintenance free batteries. Maintenance free batteries are still flooded batteries, but you can't add water. They still emit hydrogen gas when charging and corrode cable/connectors, just not as bad. When their electrolyte levels do fall, they just go bad. (throw away consumerism)


Home / Overview Starting Guide System Sizing Tool Battery Designer Wire Size Calculator Tips & Strategies Terms & Definitions
Solar Panels Charge Controllers Storage Batteries Inverters/Generators Meters & Monitoring Solar Radiation Wiring Diagrams

DISCLAIMER : The information and suggestions on this website are generally proven and accepted standards and techniques. They are, however, not meant to supersede local zoning laws or the recommendations of a licensed electrician. Always read the instructions provided with your equipment and observe all safety precautions.