A battery bank stores electricity produced by a solar electric system. If your house is not connected to the utility grid, or if you anticipate long power outages from the grid, you will need a battery bank. This series provides an overview of battery basics, including information to help you select and maintain your battery bank.
There are many types of batteries available, and each type is designed for specific applications. Lead-acid batteries have been used for residential solar electric systems for many years and are still the best choice for this application because of their low maintenance requirements and cost. You may remember the flooded version, which used to be widely used in automobiles. The sealed version is used in most types of portable equipment. Other names for sealed batteries are absorbed glass mat, valve regulated lead acid, and gel. Lithium and nickel metal hydride (NiMH) batteries, which are commonly used in cell phones, laptop computers, and camcorders because of their energy-to-weight ratios, are very expensive and may be difficult to use in residential solar applications.
The best kinds of batteries to use in a residential power system are deep-discharge lead-acid batteries specially designed for stationary solar electric systems. Some golf cart batteries may be a less expensive alternative. Car and marine batteries are not recommended for solar electric system use because they are designed to give a large burst of energy when starting a vehicle and are not made for deep discharges. Although they are sometimes used in situations in which deep discharge batteries are not available, car and marine batteries will quickly fail if used in a solar electric application.