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Solar PV

PV (Photovoltaic) solar is a technology for using the sun's energy to generate electricity using semiconductor solar cells. It's distinguished from direct solar energy, which uses the sun's energy to directly heat a building, a hot water system or both.

The electrical output of an individual solar cell is small, so they are typically grouped in modules, which in turn are grouped in arrays. Large arrays will generate a lot of electrical power. Most PV systems have battery rooms that store the power at night and on cloudy days. The output of the solar cells and batteries is direct current (DC), so most PV systems include an inverter which converts the power to alternating current (AC) for driving typical household appliances.

Solar cells are still quite expensive (although efforts are being made to drive the cost down), so the initial expense of a PV system is high. However, the electricity is produced at virtually no cost, so over time these systems can be quite economical. Some homeowners install large arrays and interconnect them with the electrical grid, so that in sunny weather the meter runs backward and the electrical utility writes them a check at the end of the month!

You can find details on photovoltaics and other renewable energy technologies at The Solar Guide. NREL, the National Renewable Energy Laboratory, has details about advances in PV technologies, and lists of PV resources for homeowners and small business owners. Brighter Energy is a new website with a wide range of news and information on cleaner energy, including an interesting story on the project by BJ's Wholesale Club to install PV arrays on the roofs of its stores. And the National Center for Photovoltaics showcase the latest on PV Research and Development.