Long-term photovoltaic performance of thin-film solar cells with diffractive microlens arrays on glass substrates

Abstract

Solar cells should provide efficient and steady long-term electricity generation in environments with heat exposure and abnormal irradiation. Thus, a diffractive microlens array was directly fabricated and employed as an optical micro-ground structure on the glass substrate of a solar panel device. The objective was to understand how diffractive micro-optic behaviours are related to photovoltaic performance under different working conditions. First, the diffractive microlens array was designed using optics/wave analysis, which was subsequently fabricated via a micro-grinding with a diamond wheel V-tip. It is shown that the diffractive microlens array not only decreases visible light reflectivity by 22.2% but also increases infrared light reflectivity from 16.73% to 22.86%. In contrast, while the ordinary microlens array decreases visible light reflectivity from 8.93% to 5.87%, it cannot increase infrared light reflectivity. This results in a higher electricity generation on cloudy days than sunny days due to infrared light heating. In comparison to ordinary microlens arrays and conventional solar cells, solar panel devices with diffractive microlens arrays increase the average electricity generation by 144% and 288%, respectively, and decrease the solar panel’s surface temperature by 8–10 °C on sunny days. This research demonstrates the value of the proposed approach to enhance selective light collection and conversion using a straightforward and controllable fabrication technique using micro-grinding.