Study on weak-light photovoltaic characteristics of solar cell with a microgroove lens array on glass substrate

Microgroove lens with 500-800 µm in depth is proposed on the glass substrate of thin-film solar cell. The objective is to improve photovoltaic characteristics under weak-light illumination. First, the micro-optical characteristics were theoretically studied in connection with micro-lens structure; then a diamond micro-grinding was employed to fabricate microgroove lens; finally, indoor conversion efficiency and outdoor electrical generation were measured. It is shown that the 800-µm-depth microgroove lens is able to absorb and scatter the inclined light to solar cell for improving weak-light conversion efficiency. It enhances the electricity generation by 118% and 185% in cloudy and overcast days, respectively.