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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-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.
Thermodynamic efficiency limits for different solar cell technologies are as follows: Single junctions ≈ 33%; 3-cell stacks and impure PVs ≈ 50%; Hot carrier- or impact ionization-based devices ≈ 54-68%; Commercial modules are ≈ 12-21%; Solar cell with an upconverter for operation in the AM1.5 spectrum and with a 2eV bandgap ≈ 50.7% [5]
The power conversion efficiency of a solar cell is a parameter which is defined by the fraction of incident power converted into electricity. [56] A solar cell has a voltage dependent efficiency curve, temperature coefficients, and allowable shadow angles.
The theoretical efficiency of MJ solar cells is 86.8% for an infinite number of pn junctions, [14] implying that more junctions increase efficiency. The maximum theoretical efficiency is 37, 50, 56, 72% for 1, 2, 3, 36 additional pn junctions, respectively, with the number of junctions increasing exponentially to achieve equal efficiency ...
The maximum theoretical limit of efficiency for conventional solar cells is determined to be only 31%, with the best silicon devices achieving an optimal limit of 25%. [ 15 ] With the introduction of quantum wells (QWs), the efficiency limit of single-junction strained QW silicon devices have increased to 28.3%. [ 15 ]
Numerical analysis shows that the "perfect" single-layer solar cell should have a bandgap of 1.13 eV, almost exactly that of silicon. Such a cell can have a maximum theoretical power conversion efficiency of 33.7% – the solar power below red (in the infrared) is lost, and the extra energy of the higher colors is also lost.