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Solar electric, or photovoltaic, systems utilize silicon-based cells that convert sunlight to electricity. Groups of these cells are wired together to form the solar arrays you may have seen on rooftops of homes and businesses. Solar electric systems produce direct current (DC) which can be used by some specialized appliances. More commonly, an inverter is installed which converts this power to the alternating current (AC) that is used by most equipment in our homes.
Some photovoltaic systems include batteries to provide back-up power at night and during cloudy weather. This is critical for homes that are far from the electrical grid, though an increasing number of homeowners are installing photovoltaic systems on homes that are already connected to the grid. These grid-connected systems provide the best of both worlds: abundant and reliable power from a traditional electric utility company, and clean renewable power from a photovoltaic system.
Photovoltaic systems are making a resurgence all around the world. The rising cost of electricity has driven some of this new interest, but improvements in solar technology are also making this renewable energy source increasingly attractive. They still require a significant investment of $15,000 to $30,000 depending on the size of the system. But for homeowners who have improved the performance of their homes in every other way, photovoltaic systems offer one more step towards energy independence.