Solar-cell efficiency

Solar-cell efficiency is the portion of energy in the form of sunlight that can be converted via <a href="/facts/Photovoltaic/5Xefaayl">photovoltaics</a> into electricity by the <a href="/facts/Solar_cell/3L814UCC">solar cell</a>.
The efficiency of the solar cells used in a <a href="/facts/Photovoltaic_system/rD4rcJB8">photovoltaic system</a>, in combination with latitude and climate, determines the annual energy output of the system. For example, a solar panel with 20% efficiency and an area of 1 m2 produces 200 kWh/yr at Standard Test Conditions if exposed to the Standard Test Condition solar irradiance value of 1000 W/m2 for 2.74 hours a day. Usually solar panels are exposed to sunlight for longer than this in a given day, but the solar irradiance is less than 1000 W/m2 for most of the day. A solar panel can produce more when the Sun is high in Earth's sky and produces less in cloudy conditions, or when the Sun is low in the sky. The Sun is lower in the sky in the winter.
Two location dependent factors that affect solar PV yield are the dispersion and intensity of solar radiation. These two variables can vary greatly between each country. The global regions that have high radiation levels throughout the year are the Middle East, Northern Chile, Australia, China, and Southwestern USA. In a high-yield solar area like central Colorado, which receives annual <a href="/facts/Solar_irradiance/SI26I7aD">insolation</a> of 2000 kWh/m2/year, a panel can be expected to produce 400 <a href="/facts/Kilowatt-hour/qvVkEmPH">kWh</a> of energy per year. However, in Michigan, which receives only 1400 kWh/m2/year, annual energy yield drops to 280 kWh for the same panel. At more northerly European latitudes, yields are significantly lower: 175 kWh annual energy yield in southern England under the same conditions.

Several factors affect a cell's conversion efficiency, including its <a href="/facts/Reflectance/TT4sBwIw">reflectance</a>, <a href="/facts/Thermodynamic_efficiency_limit/avmge0h2">thermodynamic efficiency</a>, <a href="/facts/Theory_of_solar_cells/4AYomJsH">charge carrier separation</a> efficiency, charge carrier collection efficiency and <a href="/facts/Thermal_conduction/5vRktgcS">conduction</a> efficiency values. Because these parameters can be difficult to measure directly, other parameters are measured instead, including <a href="/facts/Quantum_efficiency/MQw86Evj">quantum efficiency</a>, <a href="/facts/Open-circuit_voltage/yHPRsGkK">open-circuit voltage</a> (VOC) ratio, and § Fill factor. Reflectance losses are accounted for by the quantum efficiency value, as they affect external quantum efficiency. Recombination losses are accounted for by the quantum efficiency, VOC ratio, and fill factor values. Resistive losses are predominantly accounted for by the fill factor value, but also contribute to the quantum efficiency and VOC ratio values.
As of 2024, the world record for solar cell efficiency is 47.6%, set in May 2022 by <a href="/facts/Fraunhofer_ISE/zKWwFJt8">Fraunhofer ISE</a>, with a III-V four-junction concentrating photovoltaic (CPV) cell. This beat the previous record of 47.1%, set in 2019 by <a href="/facts/Multi-junction_solar_cell/hw0qSrCr">multi-junction</a> <a href="/facts/Concentrator_photovoltaics/zW6W1IRv">concentrator</a> solar cells developed at <a href="/facts/National_Renewable_Energy_Laboratory/UMhnJKEC">National Renewable Energy Laboratory (NREL)</a>, Golden, Colorado, USA, which was set in lab conditions, under extremely concentrated light. The record in real-world conditions is held by NREL, who developed triple junction cells with a tested efficiency of 39.5%.

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Solar-cell efficiency