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Solar-cell efficiency is the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity by the solar cell. The efficiency of the solar cells used in a photovoltaic system , in combination with latitude and climate, determines the annual energy output of the system.
The Shockley–Queisser limit, zoomed in near the region of peak efficiency. In a traditional solid-state semiconductor such as silicon, a solar cell is made from two doped crystals, one an n-type semiconductor, which has extra free electrons, and the other a p-type semiconductor, which is lacking free electrons, referred to as "holes."
For most crystalline silicon solar cells the change in V OC with temperature is about −0.50%/°C, though the rate for the highest-efficiency crystalline silicon cells is around −0.35%/°C. By way of comparison, the rate for amorphous silicon solar cells is −0.20 to −0.30%/°C, depending on how the cell is made.
Solar cells with multiple band gap absorber materials improve efficiency by dividing the solar spectrum into smaller bins where the thermodynamic efficiency limit is higher for each bin. [2] The thermodynamic limits of such cells (also called multi-junction cells, or tandem cells) can be analyzed using and online simulator in nanoHUB.
Thermophotovoltaic (TPV) energy conversion is a direct conversion process from heat to electricity via photons.A basic thermophotovoltaic system consists of a hot object emitting thermal radiation and a photovoltaic cell similar to a solar cell but tuned to the spectrum being emitted from the hot object.
Scientists used solar cells constructed of highly conductive photovoltaic materials such as gallium, indium, phosphide and gallium arsenide that increased total efficiency by over 30%. By the end of the century, scientists created a special type of solar cells that converted upwards of 36% of the sunlight it collected into usable energy.
The nominal power of PV devices is measured under standard test conditions (STC), specified in standards such as IEC 61215, IEC 61646 and UL 1703. Specifically, the light intensity is 1000 W/m 2, with a spectrum similar to sunlight hitting the Earth's surface at latitude 35°N in the summer (airmass 1.5), the temperature of the cells being 25 °C.
Reported records of solar cell efficiency since 1975. As of December 2014, best lab cell efficiency reached 46% (for ⊡ multi-junction concentrator, 4+ junctions). According to theory, semiconductor properties allow solar cells to operate more efficiently in concentrated light than they do under a nominal level of solar irradiance. This is ...