What are home solar systems?

Home solar systems, sometimes referred to as rooftop solar systems, are small arrays of solar photovoltaic modules that can be installed on a rooftop (see Figure 1) or mounted on stand-alone panels. More recent styles of rooftop systems incorporate the PV cells in the roof material itself (see Figures 2 and 3 or OWOE: Solar Roof Shingles). These systems provide electricity to help power a single home, building, or facility. Systems can be designed to provide enough electricity, when the sun is shining, to eliminate the need for power from an electrical utility company or even to provide more electricity than needed that can be sold back to the utility. See OWOE: How do photovoltaic cells work to generate electricity?.

Figure 4 shows the various components that make up the simplest form of home solar system. Starting at the solar array, the sun strikes the panels and the photovoltaic reaction in the panel materials produces a flow of low voltage direct current (DC) electricity. This DC current enters into an inverter that transforms it into higher voltage alternating current (AC), which is the type of electricity required to run typical appliances and machinery. The AC current enters the main electrical panel and is then distributed throughout the house or business to meet electrical needs. The system is also connected to the utility company's electric grid through a bi-directional electrical meter. During the day, the home solar system will provide some, or all, electrical needs. When additional power is needed, for example during the night or on cloudy days, additional electricity will flow from the grid through the meter in normal fashion. When the home solar system produces more electricity than needed, the excess will flow backwards through the meter and into the grid. The home or business is only charged for the "net" reading on the meter, i.e., the amount coming in less the amount going out, so-called "net metering".

More complex (and expensive) systems incorporate battery storage systems. Battery storage allows the excess electricity that is generated while the sun is shining to be stored and used at night. This allows a home or business to depend even less on power from the grid. It also provides for power during an outage when grid electricity isn't available. And one step further in complexity, an Electrical Vehicle (EV) charging station can be added.

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