The problem of low conversion efficiency caused by overheating of photovoltaic cells greatly affects the performance of photovoltaic cells. Recently, researchers at Stanford University have effectively reduced the excess heat radiation of photovoltaic cells by adding a special layer of quartz glass to the surface of photovoltaic cells, overcoming the cooling problems in the development of high-efficiency photovoltaic cells.
Photovoltaic cells are one of the most promising and widely used renewable energy sources on the market today. Although easy to manufacture, there has always been a problem of too low solar conversion. Excluding the inevitable energy loss, overheating of photovoltaic cells is the main reason for the low conversion efficiency. Under normal working conditions, photovoltaic cells can easily reach temperatures above 55 degrees Celsius, limiting the photoelectric conversion rate while also reducing battery life. The current cooling methods mainly use ventilation devices and liquid coolants, but these methods are lack of economy and affect photovoltaic performance.
“Our new approach can passively reduce the operating temperature of photovoltaic cells, significantly improving their energy conversion efficiency and lifetime.” Stanford University physicist and lead author of the paper, Zhu Linxiao, said that these two benefits are Conducive to the continued success and wide application of photovoltaic cell technology.
Photovoltaic cells are devices that convert sunlight directly into electrical energy. The most successful and widely used design today is the use of crystalline silicon semiconductor materials with an upper energy conversion limit of 30%. Solar energy that is not converted produces thermal radiation that reduces the performance of the photovoltaic cell. At 1 degree Celsius, the temperature of the photovoltaic cell is reduced by 0.5%. In addition, the increase in temperature will also accelerate the aging rate of photovoltaic cells, and the aging rate will be doubled for every 10 degrees Celsius increase.
"This level of conversion reduction is very serious," said Aaswath Raman, co-author of the study. In the photovoltaic industry, a lot of money is being used to solve the conversion problem. Our method of covering photovoltaic cells with a special glass surface can effectively improve photovoltaic efficiency.
In the spectrum, visible light carries more energy, while infrared light carries more heat. Different rays have different wavelengths, and different wavelengths of light have different refractive and reflectance when passing through different types and shapes of surfaces. “Quartz is transparent to visible light, but it can adjust the refraction and reflectivity of some special wavelengths of light.” Fan Shanhui explained that this design of quartz thin layer, while reflecting off the infrared, does not affect the battery pair. The absorption of visible light does not degrade the performance of photovoltaic cells, which is a near-ideal solution. Our goal is to reduce the operating temperature of photovoltaic cells and thereby increase solar conversion.
However, the above results were obtained by simulation.
Zhu Linxiao and his colleagues are currently manufacturing these devices and conducting test experiments. Their next step is to demonstrate the cooling effect of photovoltaic cells in an outdoor environment. "We believe that this work solves an important technical problem of photovoltaic power generation and optimizes the performance of photovoltaic cells. Therefore, it has great commercial potential." Zhu Linxiao said.
