The efficiency of solar panels refers to the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity by the solar cell. The efficiency of a solar panel is determined by both photovoltaic cell efficiency (cell type and design) and total panel efficiency based on such considerations as cell type, layout, and size. The efficiency of solar panels has improved dramatically in recent years, from an average of around 15% conversion of sunlight to usable energy to around 20% . High-efficiency solar panels can reach as much as nearly 23% . The efficiency of the photovoltaic (PV) cells that make up a solar panel is calculated on the basis of energy from sunlight that is converted into electricity by semiconductors.
The efficiency of solar panels used in a photovoltaic system, 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 will produce 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. The amount of light reflected away from the cells surface and the temperature are two factors that affect solar panel efficiency above and beyond the manufacturers’ rating.
As of 2022, the world record for solar cell efficiency is 47.1%, set in 2019 by multi-junction concentrator solar cells developed at National Renewable Energy Laboratory (NREL), Golden, Colorado, USA. However, most commercial panels have efficiencies from 17% to 20% . Researchers have developed PV cells with efficiencies approaching 50% . Assuming intermediate efficiency, PV covering 0.6% of U.S. land area would generate enough electricity to meet national demand.
In conclusion, the efficiency of solar panels has improved significantly in recent years, and it is determined by both photovoltaic cell efficiency and total panel efficiency based on such considerations as cell type, layout, and size. The efficiency of solar panels used in a photovoltaic system, in combination with latitude and climate, determines the annual energy output of the system.
