Photovoltaic power generation cost
More than 60% of the cost of photovoltaic power generation systems comes from solar cells. Since the 1970s, great progress has been made in the research of solar cell materials, structures and processes, the efficiency of products has been improved, the cost has been reduced, and the scale of ground applications has gradually expanded. However, compared with conventional power generation, the cost of using solar photovoltaic power generation is still higher. Reducing the thickness of photovoltaic cell silicon wafers is an effective technical measure to reduce the cost of crystalline silicon solar cells. The average thickness of silicon wafers has been reduced from 0.3mm in 2003 to 0.18mm in 2007. Thin-film solar cells are made of cheap glass, stainless steel or plastic substrates attached with very thin photosensitive materials. They are cheaper than crystalline silicon technology that uses more materials, and their price advantage can offset the problem of low efficiency.
The cost of photovoltaic power generation reaches the level of conventional energy generation electricity prices, which is a concern. The Energy Research Institute of the National Development and Reform Commission of China proposed that the self-use of distributed power generation systems can be compared with the price of electricity sold by the grid, which shows that it is easier to achieve parity on the grid for self-use of photovoltaic power generation. However, if it is the grid-connected medium and high voltage on the transmission side, since the on-grid tariff of China’s conventional electricity is generally only 0.3 yuan/kWh, it is still quite difficult to achieve parity on the grid at this level.
In 2006, the cost of grid-connected photovoltaic power generation system was about 50,000 yuan/kW. Wuxi Suntech, the earliest solar energy company listed overseas in China, announced in July 2008 that it planned to reduce the cost of solar power generation to 1 yuan/(kWh) within 5 years. Based on the development of thin-film technology and its price advantages, thin-film solar cells are expected to be the first to reach grid equivalence.
Grid-connected photovoltaic power generation
With the rapid development of photovoltaic power generation, access to the grid has become a key issue, and grid connection has also become an important part of the future photovoltaic market. There are already many international standards for the requirements of grid-connected photovoltaic power plants. Chinese standards are scattered among some traditional standards, most of which are only requirements for voltage and current harmonics, voltage and frequency deviations, voltage fluctuations and flicker, DC components and power factor. When the capacity of photovoltaic power station is small, these parameter requirements are basically applicable. However, when the scale of photovoltaic power plants becomes larger and larger (tens or even hundreds of megawatts), it is necessary to consider factors such as photovoltaic power plants receiving grid dispatch and participating in grid management, specifically including low voltage ride through, reactive power compensation, active power derating, etc.
At present, the development of grid-connected solar photovoltaic power generation projects in China is relatively fast. In March 2010, the grid-connected solar photovoltaic power generation project of the Hamburg Pavilion of the German Exhibition Hall of the World Expo, which was undertaken and installed by Shanghai Polaris Solar Photovoltaic Equipment Installation Engineering Co., Ltd., was successfully completed and passed the acceptance. The maximum solar cell array design power of the solar photovoltaic power generation project is 22kW, the maximum power point tracking voltage range is 300~650V, and the number of arrays that can be connected is 4. The entire solar photovoltaic power generation system is installed on the roof of the pavilion building, forming part of the green energy supply of this peculiar building.
Providing power with photovoltaic systems will be the main development trend of Tibet’s telecommunication power supply. At present, Tibet has built 14 small independent photovoltaic power stations at the county level, becoming the province with the largest total installed capacity of photovoltaic power stations and photovoltaic cells in China. Qinghai Province implemented the power transmission project in 2003. It plans to build 112 photovoltaic power stations in Yushu, Guoluo, Huangnan and other places, with a total installed capacity of 3943kW, and the capacity of each power station is between 10-50kW. The project is currently being implemented. After the power station is completed, the power supply will be supplied for more than 5 hours a day, which can basically solve the electricity problems of daily life such as lighting and watching TV.
Solar energy is a low-density, intermittent, and constantly changing spatial distribution of energy. Photovoltaic power generation systems can directly convert solar energy into high-grade energy-electrical energy. This puts forward higher requirements for the collection and utilization of solar energy. At present, how to maximize the utilization rate of solar energy and reduce the cost of photovoltaic system power generation is a research hotspot of scholars from various countries.