Employing a backup generator in a stand-alone PV system is a prudent addition. Trying to produce every last watt-hour needed can cost a pretty penny in added PV array and battery bank capacity—much more than the cost of a generator. That’s why using a backup generator in a stand-alone PV system can make financial sense. A reliable backup source allows greater design flexibility and, most often, a smaller and more cost-effective system. The size of the PV array can be reduced to a more affordable size, while a backup generator can make up the difference when the solar resource is inadequate. In addition, equalization, an important aspect of battery maintenance, can be difficult to achieve with a PV array alone. As long as there is fuel in the generator, you aren’t dependent on the weather to keep the lights on and the beer cold. (For more information on backup generators, see “Engine Generator Basics” in HP131.)
