The loss of low-energy photon energy. When the photon energy in the solar panel is less than the forbidden band width of the semiconductor, the photons will directly penetrate the semiconductor material without being absorbed or generating electron-hole pairs, and the energy of this part of the light is lost about 26%.
High-energy light is a loss of energy. When the photon energy is greater than or equal to the band gap of the semiconductor, the photon will be absorbed by the semiconductor material, and the energy of the photon larger than the band gap of the semiconductor will be released in the form of heat, and the energy of this part of the light will lose about 40%.
Absorption efficiency and reflection loss. Not all semiconductor materials have the same ability to absorb light. A semiconductor material with a larger light absorption coefficient absorbs the same amount of photons at a thinner thickness as a semiconductor material with a smaller light absorption coefficient at a thicker thickness. the same number of photons. While incident photons are effective light, they cause reflection losses due to surface reflections. The reason for the reflection on the surface of the solar panel is (1) the direct reflection of the electrode surface where it is located. (2) Reflection due to the difference in refractive index between semiconductor material and air.
Open circuit voltage loss. The light-generated carriers move in the PN junction under the action of the electric field in the space charge region, polarize the charge, and generate a voltage. In the PN junction, the power released by the diffusion potential determined by the doping impurity concentration cannot be taken out, and this loss is called the voltage factor loss, which is about 40%.