Photovoltaic power generation refers to a form of power generation that uses the photovoltaic effect of semiconductor materials to directly convert solar radiation energy into electrical energy. Photovoltaic effect refers to the change in the distribution and concentration of carriers that can conduct current inside an object after absorbing light energy, resulting in the effects of current and electromotive force. This effect can be produced in gases, liquids and solids. The electric energy converted from solar energy can be directly stored in energy storage equipment for use when needed, or it can be connected to the grid according to the actual situation of electricity consumption, so that the solar power generation system and the large grid system can be connected to the grid.
The photovoltaic power generation can be divided into grid-connected photovoltaic power generation system and independent photovoltaic power generation system according to whether it is connected to the public grid.
After rapid development in recent decades, photovoltaic power generation has developed to the third generation of power generation technology. Looking at the evolution of photovoltaic power generation technology, we can find:
The first generation of photovoltaic power generation technology is mainly crystalline silicon photovoltaic power generation, there is a difference between monocrystalline silicon and polycrystalline silicon. At present, the monocrystalline silicon cell technology is nearly mature, and the improvement of its photoelectric conversion efficiency mainly depends on the monocrystalline silicon surface microstructure treatment and zone doping process. At the best angle of sufficient light, the total photoelectric conversion efficiency of monocrystalline silicon cells can reach 20%~24%. Polycrystalline silicon raw material is the common upstream raw material of the semiconductor industry and photovoltaic power generation industry, and the conversion efficiency of polycrystalline silicon cells is not as good as that of monocrystalline silicon. In order to adapt to the continuous and stable growth of photovoltaic market demand, solar cell companies have to purchase semiconductor-grade silicon at a higher price to produce solar cells, which undoubtedly increases the cost of the photovoltaic power generation industry and restricts the development of the photovoltaic power generation industry. The advantage of the first generation of photovoltaic power generation technology is that the photoelectric conversion rate is relatively high, but the disadvantage is that the price is more expensive, the production of polysilicon consumes more energy, and it is easy to pollute the environment.
The core of the second-generation photovoltaic power generation technology is the bondable thin-film battery. The advantage is that the material consumption is small and the price is lower. The disadvantage is that the photoelectric conversion rate is only half of that of crystalline silicon, the module attenuation is large, and the module with the same power occupies an area. The area is also larger. The main varieties are: ①Amorphous, nanocrystalline, microcrystalline and other silicon films; ②CIGS, a film composed of copper indium gallium selenium; ③TeCd cadmium telluride film.
The third generation of photovoltaic power generation technology uses the “solar smelting + tracking + concentrating + high-efficiency concentrating silicon cell” technology to generate electricity. This is the most essential technical difference from the first and second generations. The third-generation photovoltaic power generation technology can increase photovoltaic power generation by 30%-40% and reduce the consumption of crystalline silicon by 30%-40% through tracking systems and concentrating systems.
It can be seen from the development history of the above photovoltaic technology that the main goal of each generation of photovoltaic power generation technology is to reduce manufacturing costs and increase solar cells by improving existing manufacturing processes, designing new battery structures, and developing new battery materials. By increasing the effective receiving area of photovoltaic modules and adopting the maximum power point tracking technology, the total power generation efficiency of the photovoltaic power generation system is improved.