Solar power systems include several components working together to convert the sun’s energy into electrical power that can be connected to a building’s standard electrical infrastructure and the utility grid.
Photovoltaic, or PV, cells are the basic engine of a solar power system. PV cells convert the sun’s energy into electricity. A PV cell is most often made of a thin wafer of silicon modified with small amounts of other materials that give the silicon wafer special electrical properties. When sunlight hits a PV cell, it produces an electric current. PV cells are connected together in a solar module, which has a non-reflective glass front, a protective insulating back sheet and an aluminum frame for strength and mounting.
A. Solar Modules are connected electrically to generate direct current electricity at the desired voltage and current. Panels are installed on rooftops or open areas, such as parking lots or fields that have full sun exposure. (Solar panels can collect solar energy on cloudy days.) A larger grouping of solar panels constitutes a “solar array”. Large non-residential solar facilities often contain multiple arrays, sometimes located on different buildings at a given site.
B. The Inverter transforms direct current (DC) electricity produced by the solar panels into alternating current (AC) electricity - the form of electricity used by most standard lights, motors, computers and air conditioners. The inverter also provides safety functions such as automatic shutdown of the solar electric system in the event of a power failure.
C. Electrical Panel - Power travels from the inverter to your electrical service panel (your breaker box) where it is distributed to electrical loads throughout your facility. The AC safety, or disconnect, switch is a manual switch that can be used to disconnect a building’s electrical system from the solar electricity system.
D. Utility Grid - Excess power produced by the solar modules flows into the grid through your electric meter, causing your meter to run backwards and gaining you a credit with the utility company.
E. Net Metering is an agreement between a utility company and you, the customer. The agreement states that the utility will credit your account for excess electricity you produce and feed into the utility grid.
If you choose to install a Time-of-Use Meter you can be credited for power at different rates; peak rates and off peak rates. Rates are dependent on the time of day, day of the week, and month of the year. Peak periods are typically week day summer afternoons. When you send power to the utility grid during peak times, you will receive a credit at the higher, peak rate. When you draw on your credit at off peak times your account will be debited at off peak rates.
Most people will benefit by installing the time-of-use meter. Keep in mind that you will receive a credit from the utility when you are generating more power than you are using. If all of the power being produced by your solar energy system is immediately being used, your meter will not “spin backwards”.