page_title: Photovoltaics
section_title: Photovoltaic systems
hierarchical_section_title: Photovoltaics / Applications / Photovoltaic systems
caption_attribution_description: English: Nine million cadmium telluride solar modules now cover part of Carrizo Plain in southern California. The modules are part of Topaz Solar Farm, one of the largest photovoltaic power plants in the world. At 9.5 square miles (25.6 square kilometers), the facility is about one-third the size of Manhattan island, or the equivalent of 4,600 football fields. Construction at Topaz began in 2011. The plant was mostly complete by November 2014, when it was turned on and began to generate electricity. By February 2015, all construction activity ended and plant operator BHE Renewable was set to announce that the project was officially complete. When operating at full capacity, the 550-megawatt plant produces enough electricity to power about 180,000 homes. According to BHE estimates, that is enough to displace about 407,000 metric tons of carbon dioxide per year, the equivalent of taking 77,000 cars off the road. From the ground level, the scope of the facility is difficult to comprehend. Visitors to Topaz describe rows of solar panels that seem to stretch endlessly into the horizon. This satellite image, captured on January 2, 2015, by the Operational Land Imager on Landsat 8, helps put the facility into perspective. Solar arrays appear gray and charcoal. The surrounding farmland and grasslands appear brown and green. The power plant is situated within a plain flanked by the Caliente Range to the west and the Temblor Range to the east. Topaz’s solar modules are mounted together on panels supported by steel columns; the structure holds the modules about 5 feet (1.5 meters) above the ground. Rows of panels are laid in a way that form large geometric shapes that are defined in part by the presence of access roads, stream beds, and preexisting infrastructure. The northernmost portions of the solar farm, which are close to a transmission line, were built first. Mid American Renewables and Gunther Portfolio have published interesting aerial video and photographs that show additional views of the plant at various stages of construction.
context_page_description: Photovoltaics is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry.
  PV has become the cheapest source of electrical power in regions with a high solar potential, with price bids as low as 0.01567 US$/kWh in 2020. Panel prices have dropped by the factor of 10 within a decade. This competitiveness opens the path to a global transition to sustainable energy which would be required help to mitigate global warming. The situation is urgent: The emissions budget for CO
  2 to meet the 1.5 degree target would be used up in 2028 if emissions remain on the current level. However, the use of PV as a main source requires energy storage systems or global distribution by high-voltage direct current power lines causing additional costs.
  A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power. PV installations may be ground-mounted, rooftop mounted, wall mounted or floating. The mount may be fixed or use a solar tracker to follow the sun across the sky.
context_section_description: A photovoltaic system, or solar PV system is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and directly convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling and other electrical accessories. PV systems range from small, roof-top mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large utility-scale power stations of hundreds of megawatts. Nowadays, most PV systems are grid-connected, while stand-alone systems only account for a small portion of the market.
  Rooftop and building integrated systems
  Photovoltaic arrays are often associated with buildings: either integrated into them, mounted on them or mounted nearby on the ground. Rooftop PV systems are most often retrofitted into existing buildings, usually mounted on top of the existing roof structure or on the existing walls. Alternatively, an array can be located separately from the building but connected by cable to supply power for the building. Building-integrated photovoltaics (BIPV) are increasingly incorporated into the roof or walls of new domestic and industrial buildings as a principal or ancillary source of electrical power. Roof tiles with integrated PV cells are sometimes used as well. Provided there is an open gap in which air can circulate, rooftop mounted solar panels can provide a passive cooling effect on buildings during the day and also keep accumulated heat in at night. Typically, residential rooftop systems have small capacities of around 5–10 kW, while commercial rooftop systems often amount to several hundreds of kilowatts. Although rooftop systems are much smaller than ground-mounted utility-scale power plants, they account for most of the worldwide installed capacity.
  Concentrator photovoltaics
  Concentrator photovoltaics (CPV) is a photovoltaic technology that contrary to conventional flat-plate PV systems uses lenses and curved mirrors to focus sunlight onto small, but highly efficient, multi-junction (MJ) solar cells. In addition, CPV systems often use solar trackers and sometimes a cooling system to further increase their efficiency. Ongoing research and development is rapidly improving their competitiveness in the utility-scale segment and in areas of high solar insolation.
  Photovoltaic thermal hybrid solar collector
  Photovoltaic thermal hybrid solar collector (PVT) are systems that convert solar radiation into thermal and electrical energy. These systems combine a solar PV cell, which converts sunlight into electricity, with a solar thermal collector, which captures the remaining energy and removes waste heat from the PV module. The capture of both electricity and heat allow these devices to have higher exergy and thus be more overall energy efficient than solar PV or solar thermal alone.
  Power stations
  Many utility-scale solar farms have been constructed all over the world. As of 2015, the 579-megawatt (MWAC) Solar Star is the world's largest photovoltaic power station, followed by the Desert Sunlight Solar Farm and the Topaz Solar Farm, both with a capacity of 550 MWAC, constructed by US-company First Solar, using CdTe modules, a thin-film PV technology. All three power stations are located in the Californian desert. Many solar farms around the world are integrated with agriculture and some use innovative solar tracking systems that follow the sun's daily path across the sky to generate more electricity than conventional fixed-mounted systems. There are no fuel costs or emissions during operation of the power stations.
  Rural electrification
  Developing countries where many villages are often more than five kilometres away from grid power are increasingly using photovoltaics. In remote locations in India a rural lighting program has been providing solar powered LED lighting to replace kerosene lamps. The solar powered lamps were sold at about the cost of a few months' supply of kerosene. Cuba is working
caption: Satellite image of the Topaz Solar Farm
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