Crystalline silicon and thin-film solar photovoltaic cells are the two major technology camps now and in the next decade. Crystalline silicon solar cells have dominated the photovoltaic market with high conversion efficiency in the past and now. The breakthrough in the original conversion efficiency of thin-film batteries and the relatively low cost have attracted more attention from investors in the past two years and are in a period of rapid development.
Currently commercialized solar cell technologies include crystalline silicon cells, amorphous silicon solar cells, cadmium telluride thin film solar cells, and concentrating solar cells. CIGS thin-film solar cells may also be industrialized in the future. Among them, crystalline silicon solar cells account for more than 85% of the entire photovoltaic market. The average conversion efficiency of large-scale production of monocrystalline silicon solar cells has reached 16.5%, while the conversion efficiency of polycrystalline solar cells is between 14.5% and 15.8%. It is reported that the average conversion efficiency of the SE battery that has been mass-produced at CLP is 17.5%, and its single crystal solar battery can achieve a conversion efficiency of 18%. Wuxi Suntech, a benchmarking company in the Chinese solar industry, has announced that the conversion efficiency of Pluto batteries has reached 18%.
In the future blueprint for the development of solar cells, thin-film batteries will become a new highlight at low cost, and attempts to improve their conversion efficiency by improving the process will greatly reverse the pattern of the photovoltaic market.
Raw materials account for an important proportion of the cost structure of solar cells. Thin-film batteries can rise in the current development of the photovoltaic industry and cost factors play a key role. According to Dr. Sun Haiyan, general manager of technical marketing at Oerlikon's solar energy division in Asia, whether crystalline silicon or thin-film solar cells, raw materials account for about 60%-70% of the total cost of the total photovoltaic cells, and the cost of thin-film solar cells is in the past and in the future. It is much lower than the cost of crystalline silicon solar cells. Figure 1 shows the PV cost model established by Dr. M. Green in 2003. In 2003, the price of polysilicon was 30 US dollars/kg. According to the model, when the installed capacity of the system is 1GW, the price per KW of conventional thin film solar cells is about One-half of polysilicon solar cells. The new thin-film solar cell technology will continue to expand the price advantage of this unit of electricity.
In the past few years, in order to reduce the cost of crystalline silicon solar cells, the thickness of the silicon wafer used to make cells has been reduced from 300 um to 180 um. Dr. Sun Haiyan believes that even with the release of polysilicon production capacity next year, There will be a certain degree of decline, but from a cost perspective, thin-film batteries still have significant cost advantages.
Glass, one of the main raw materials for thin-film batteries, accounts for about 40% of the cost of raw materials. Amorphous microcrystalline thin-film batteries require ultra-clear glass because ultra-white glass has high light transmittance and has a good absorption of sunlight. At present, there are already some photovoltaic glass manufacturers in China that have reached a certain scale, such as Shandong Jinjing, CSG, and Yaopi. This provides a rich supply of raw materials for the large-scale production of thin-film batteries.
At the same time, the conversion efficiency of the thin film has also been greatly improved in the past few years. The theoretical upper limit of the conversion efficiency of the thin film solar cell using the amorphous double junction technology is 15%, which is the highest in the reported mass production. Conversion efficiency has reached about 11%. The development of crystalline silicon cells has also promoted the rapid development of thin-film solar cells. Thin-film solar cells currently have the basic conditions for large-scale production.
One of the giants of thin-film solar cell solutions used the Sunfab product line to dominate the thin-film solar photovoltaic market. The most fascinating aspect of Sunfab was to rewrite the size of the thin-film solar cell glass substrate, increasing the size to 2.2 meters X 2. 6 meters, the total area has reached 5.7 square meters, the area is 4 times that of ordinary thin-film solar cells, such a large area of ​​solar cell modules can not only save production costs, in the installation of the system can greatly reduce the installation of materials and installation Manpower.