Batteries are a very important part of a home solar power system. Solar power is only generated during daytime hours when the sun is shining. The lifestyle of most people dictate that the major portion of the energy they consume in their home is at night when they are home. A bank of batteries will store the electricity generated during the day and discharge it at night for use in the home. The battery will also provide a consistent flow of electricity to the home, preventing damage to electronics devices. Using electricity directly from the solar cells can damage delicate electronics because output from a cell can vary greatly due to changing light conditions.

Using the proper type of battery is vital. Deep-discharge, lead acid batteries are the best storage medium for the solar home power system. Automobile batteries are shallow-discharge batteries designed to provide a short, powerful burst of energy to start a vehicle. They are harmed if more than twenty percent of their power is discharged. Lead acid, deep discharge batteries can discharge fifty to seventy percent of their stored charge without harming them.

There are three major types of lead acid batteries available for use in home solar power systems. These are the flooded, gel, and absorbed glass mat (AGM) batteries. The flooded type is the cheapest of the three and should give many years of service. They have caps for adding water and should be checked regularly. Gel batteries are sealed and will need less maintenance. AGM batteries uses a woven glass mat to hold the electrolyte in the battery. These batteries are also sealed and will not leak. They also maintain voltage better, have a lower rate of self discharge and have a longer life. They are also much more expensive than other types of batteries.

The typical solar home power system needs more than one battery. Individual batteries are connected together in a string, which can either be a twelve, twenty-four, or forty-eight volts. These strings are then connected together to form a battery bank. The bank is circuited through an inverter which converts the DC voltage of the batteries to the AC current needed by household appliances.

Batteries work best if they are installed in an area where the temperature stays between seventy and seventy-five degrees. Lead acid batteries will discharge toxic gases when charging, so they should not be installed inside the home. A separate, warm area is needed for them, or ventilation provided which will draw off these fumes. Gel and AGM batteries do not give off gases when they charge, so they may be installed without venting.

A charge controller installed between the solar panel and the solar cell will protect the batteries from damaging overcharge, and will also sense when the battery is getting low in charge and will shut the circuit down to prevent damage to the battery. Various meters can be installed to monitor the charge and available voltage in the battery.

A well chosen storage battery can help your solar home power system deliver consistent, reliable power to your home during periods of low light levels. They can also help protect the electronics in the home by delivering a constant flow of electricity at a stable rate. If installed in a suitable environment the batteries should give many years of service.

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