Solar energy is the cleanest and richest renewable energy available. Solar photovoltaic cells or panels are devices that convert solar energy into electrical energy. Intensive development and large-scale production of solar panels have begun in this new millennium. In 2018, the global installed capacity of solar PV has reached 494.3gw, which is expected to increase by more than 1 TW between 2019 and 2030 (source: global data). It is estimated that most of the new production capacity during this period will come from China, India and other Asia Pacific countries. With the rapid growth of installed capacity and the improvement of technical level, the average expenditure cost of establishing solar PV has been significantly reduced, but the gap between countries is still large. The reduction of production costs and the support of government policies have reduced the average system price of solar photovoltaic. In 2010, the average capital cost of global solar photovoltaic power stations was US $4162 / kilowatt, and decreased to US $1240 / kilowatt in 2018. According to the cost estimates of some countries, it is expected to further decrease to US $997 / kilowatt by 2030. The following figure shows the price trend of the top five solar photovoltaic countries and the average photovoltaic system in the world from 2010 to 2018.