Silicon solar cells

In this section we will focus on silicon solar cells as the most commonly used solar cells in photovoltaic systems. Efficiency of solar cells is limited by several factors. Energy photons by increasing the wavelength of light decreases, the maximum wavelength at which photons have enough energy rate for silicon is 1.15 mm. Radiation with a wavelength greater warming causes only solar cells. Photon can cause only one pair of electro-hole, so that also at lower wavelengths than the maximum peak occurs photons, which also only heat the cell. The ceiling of the conversion of incoming light energy in a solar cell is approximately 23% (with an experimental silicon solar cells). When using other materials, the efficiency can be higher (experimentally up to 30%), due to a wider spectrum of light, the incident radiation cells can be converted into electricity. Own loss of solar cells appear to contact the network (own crown cover), the internal resistance of the cell and the reflection of solar radiation on the cell surface. Crystalline solar cells are usually in the form of slices, thickness 0.3 mm, cut from the Si ingot with a diameter of 10 to 1 5 cm, and generate around 35mA of current per cm2 (up to 2 A / cell) surface at a voltage of approximately 550 mV at full brightness. Laboratory performance of these cells have an efficiency of 18% to 15% classical.