You don’t need to know the detailed physics of solar electricity to understand its appeal. However, it’s wise to be familiar with some fundamentals before you shop.
Solar electric technology converts sunlight directly into electricity whenever sunlight strikes the solar electric modules. The amount of electricity produced by a system will vary. More electricity is generated when the light is most intense (a sunny day) and strikes the solar electric system’s modules directly (when the sun’s rays are perpendicular to the modules).
Solar electric systems shouldn't’t be confused with solar water-heating systems that operate by using the sun’s rays to heat water. Rather, solar electric technology produces electricity directly from electrons that are freed when sunlight interacts with the semiconductor material in the solar electric cells. These cells are the basic building blocks of the system and are wired together to form modules, the system components that are sold commercially.
Power output from modules ranges from 10 to 300 watts. One or more modules are installed as part of a typical solar electric system. The modules are then connected to an electric utility through an inverter that changes the Direct Current (DC) produced by the cells into Alternating Current (AC). AC current is the same form of electricity supplied by your local electric utility and can be used to operate heating and cooling systems, appliances, lights, etc.
Solar Electric System Components
By connecting a solar electric system to your electric utility, you can automatically use power from both your system and the utility when your system’s output is low, such as on a cloudy day. Conversely, you can send any surplus power produced by your system back to the electric utility for a credit on future electric bills (this is called net metering).
If you are interested in backup capability in the event of a power outage, you can purchase a solar electric system that includes batteries. A stand-alone system (not connected to an electric utility) will incorporate batteries in order to provide power at night and on cloudy days.