Electricity for homes or other buildings farther than a couple football fields from the nearest electrical lines, may be cheaper if obtained from photovoltaic cells than by buying electricity from the local power utility, because of the cost of running an electrical line to the house. In most urban areas, however, buying electricity from a utility is much cheaper than using photovoltaics.
The cost of using photovoltaic technology depends not only on the photovoltaic cells themselves but also on the batteries and equipment needed to condition the electricity for household use. Modules made of groups of photovoltaic cells set side-by-side and connected in series generate direct current (DC) electricity at a relatively low voltage, but most household appliances use 120-V alternating current (AC). Inverters and power conditioners can transform DC to AC current at the correct voltage.
The types of appliances in the house are also a consideration for whether to use photovoltaic. Some devices—like televisions, air conditioners, blow-dryers, or laser printers—require a lot of power, sometimes all at once. Because photovoltaic cells do not change the amount of voltage they can supply, this sort of load can drain batteries rapidly. Many people with houses powered by photovoltaic cells buy energy-efficient lights and appliances and limit the number of unnecessary electrical devices in their homes.
In remote parts of the world, entire villages are powered by photovoltaic systems. A few utility companies in the United States and Europe run "solar farms" to produce electricity. Other industrial uses exist for photo-voltaic cells, too. These are usually low-power applications in locations inconvenient for traditional electrical sources. Some emergency roadside phones have batteries that are kept charged by photovoltaic cells. Arrays of cells power cathodic protection: the practice of running current through metal structures to slow corrosion.
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