How Small Solar Electric Systems Work

Solar electric systems, also known as photovoltaic (PV) systems, convert sunlight into electricity.

Solar cells—the basic building blocks of a PV system—consist of semiconductor materials. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms. This phenomenon is called the "photoelectric effect." These free electrons then travel into a circuit built into the solar cell to form electrical current. To see a simulation of the photoelectric effect, please view our Solar Power Basics animation. Only sunlight of certain wavelengths will work efficiently to create electricity. PV systems can still produce electricity on cloudy days, but not as much as on a sunny day.

The basic PV or solar cell typically produces only a small amount of power. To produce more power, solar cells (about 40) can be interconnected to form panels or modules. PV modules range in output from 10 to 300 watts. If more power is needed, several modules can be installed on a building or at ground-level in a rack to form a PV array.

PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day.

Because of their modularity, PV systems can be designed to meet any electrical requirement, no matter how large or how small. You also can connect them to an electric distribution system (grid-connected), or they can stand alone (off-grid).

An illustration showing a residential grid-connected small solar electric or photovoltaic system. It shows two square-shaped solar panels, each containing nine smaller squares, on the roof of a house. You can see how the electric current travels from the solar panels to an inverter box. From the inverter box, the electric current travels to a meter box and then to an electricity transmission tower, referred to as the utility service. Inside the house, from the inverter box, you see the electric current powering two lights, a television, and a clothes washer and dryer.

Download high-resolution diagram: JPG (ZIP 124 KB) | EPS (ZIP 541 KB)

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Related Links
PV Fundamentals
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