China's first solar collector tube launched in Shanghai

On May 5, 2011, with the support of the technical research and development team of Peking University, the first copper indium gallium selenide (CIGS) solar collector tube developed by Henan Yanyuan Photovoltaic Technology Co., Ltd. was officially released in Shanghai, becoming the most eye-catching project at the 6th Asian Solar Photovoltaic Exhibition. The exhibition of this new solar cell product with completely independent intellectual property rights marks the start of the industrialization journey of solar collector tubes in China, and is a new highlight in the development of my country's photovoltaic industry.

Solving the problem of photovoltaic cost

In recent years, the renewable energy industry represented by solar energy and wind energy has flourished, and technological innovation has continuously promoted the development of solar thermal photovoltaic application technology, but the high cost is still the biggest bottleneck for the popularization and application of solar energy.

At present, crystalline silicon solar cells still occupy the mainstream position in the world's photovoltaic industry, followed by thin-film solar cells, which occupy about 10% of the market. In production, the properties of polysilicon production process determine that there will be high energy consumption problems in its industrial chain production links, especially in polysilicon purification. Some companies with low technical levels even have high pollution problems. In application, crystalline silicon solar cells have greatly reduced their originally high photoelectric conversion efficiency due to their temperature effect and narrow spectral response range, and the power generation conditions are harsh. However, thin-film solar cells have always been criticized for their low conversion efficiency, complex production process, expensive production equipment, and difficulty in achieving large-scale production. It can be said that for a period of time, high power generation costs will still be the common shortcoming of the two major types of solar cells, and reducing production costs will continue to be the main tone of future development in the field of solar photovoltaics.

It is understood that the mainstream in the thin-film solar cell family currently includes three types of thin-film solar cells: silicon-based amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). Among them, copper indium gallium selenide thin-film solar cells are internationally known as "the next generation of very promising new thin-film solar cells."

As a type of thin-film battery, copper indium gallium selenide cells have the characteristics of low material and energy consumption, good weak light performance, no pollution to the environment, and cost recovery compared with crystalline silicon cells. Compared with other thin-film batteries, their conversion rate is far beyond the reach of other thin-film batteries. Moreover, the raw materials used in them are very abundant in China, and it is relatively easy to obtain the raw materials.

Gan Zizhao, an academician of the Chinese Academy of Sciences and a professor at the School of Physics of Peking University, spoke highly of the technology. In an interview with our reporter, he said: "This is a brand-new form of application of copper indium gallium selenide (CIGS) thin-film solar cells, and it has explored a new path for large-scale production of CIGS."

The project has obvious advantages

At the exhibition site, a booth of Henan Yanyuan Photovoltaic Exhibition was always crowded with people, and some well-known experts in the field of photovoltaic research and chairmen of well-known photovoltaic companies came to inspect one after another.

The reporter found that the display cabinet displayed every detailed step of the production of copper indium gallium selenide thin-film solar collector tubes from the initial ordinary glass tubes through various processes. A technician introduced that the appearance of the solar collector tube is similar to the arrangement of heat collector tubes used in solar water heaters. Its substrate can be ordinary glass tubes or flexible materials such as organic matter. Molybdenum metal is used as the back electrode, copper indium gallium selenide is used as the main absorption layer to absorb light energy, and the surface low-resistance layer electrode mainly functions as light transmission, conductivity, and anti-reflection.

"This unique tubular solar collector design solves the global problem of low yield rate in large-scale production of copper indium gallium selenide," said Wang Hui, general manager of Henan Yanyuan Photovoltaic. "Currently, the yield rate of large-scale copper indium gallium selenide thin-film solar cells is less than 5%. If there is a slight flaw on a larger copper indium gallium selenide thin-film solar cell module, the module may be completely scrapped. The solar collector is a solar collector made of large-area copper indium gallium selenide one by one, arranged according to its independent tubular structure, which not only improves the power generation efficiency, but also can achieve a yield rate of more than 90%."

During the interview, the reporter learned that the research and development team that cooperated with Yanyuan Photovoltaic this time was a well-known technical team from Peking University in the solar energy industry. In 1996, the team cooperated with the University of Sydney in Australia to develop the first medium- and high-temperature solar collector tube in China. At present, the solar collector tube has been industrialized as the main component of solar water heaters and has been widely used.

Professor Lu Zhenji, chief engineer of the project, said in an interview: "After a year-long pilot experiment, we have successfully developed a new type of CIGS tubular solar cell. The preliminary design specifications of the solar collector tube are: the collector tube length is 1200mm, the inner tube diameter is 30mm, the outer tube diameter is 35mm, and the photoelectric conversion efficiency reaches 9%."

Professor Lu also introduced that the product can achieve solar thermal power cogeneration while reducing the surface temperature of the battery and maintaining the conversion efficiency. It is worth mentioning that the R&D team has also designed industrial production equipment for solar collectors and a completely domestically produced industrial production line with independent intellectual property rights, which greatly reduces the cost of construction and subsequent maintenance costs and solves the problem of excessive one-time investment in thin-film solar cell production.