Using crystalline silicon cells and thin film cells for photoelectric conversion are the first and second generation solar energy utilization technologies respectively, which have been widely used. Concentrator photovoltaics solar energy technology, which uses optical elements to gather sunlight and then generate electricity, is considered to be the third generation technology of the future development trend of solar power generation.
Concentrating photovoltaic (PV) is a kind of technology that uses concentrating technology to concentrate sunlight on the surface of solar cells to generate electricity by replacing expensive solar cells with relatively cheap concentrators.
Multi Junction solar cells used in concentrator photovoltaics are the core and foundation of concentrating photovoltaic technology, and crystalline silicon solar cells were mainly used in the early stage. Due to the high photoelectric conversion efficiency of GaInP / GaAs / Ge multi junction solar cells, and its high temperature characteristics, it can realize high-power concentrating. At present, GaInP / GaAs / Ge multi junction solar cells are widely used in the world to develop high-power concentrator photovoltaics technology. The typical GaInP / GaAs / Ge triple junction cell is composed of about 30 layers, which are fabricated by MOCVD or MBE technology.
Generally, the tracking system must be used to ensure the focusing effect for the focusing system with the concentration rate more than 10. Tracking system can be divided into single axis tracking and double axis tracking. According to the combination of rotation axis, the two axis tracking system can be divided into polar axis type, base type, horizontal pivot type, turntable type and so on. Generally speaking, the polar axis control is relatively simple, but the accuracy is slightly low; The polar and pedestal structures are relatively simple and easy to install, but they are greatly affected by the wind, and the single system capacity is limited by the structural strength and cost; The horizontal pivot type is less affected by wind and occupies less space. It is widely used in roof applications, but its installation is relatively complex. The turntable structure is least affected by the height and wind force, which can effectively reduce the structure cost, and the single system capacity can also be larger. However, turntable installation is the most complex of all forms, and a lot of adjustment work needs to be done to ensure the consistency of each solar array.