High-efficiency upright solar panels with antireflective microprism-imprinted sheets

Upright solar panels (SPs) are exposed to direct sunlight within the restricted trajectory of the sun's diurnal motion. These SPs encounter varying incident angles depending on the orientation of their faces, which can be large at high latitudes. Here, guided by geometric optics, we design a wedge-shaped microprism sheet for upright SPs to mitigate reflection losses. This microprism sheet achieves a surface reflectance below 0.01 for all incident angles and wavelengths of direct sunlight. Furthermore, ray optics simulations that trace the trajectory of each principal light path through the microprism sheet account for its omnidirectional near-unity transmittance. These optical characteristics enhance the photovoltaic performance of the SPs, yielding a more pronounced increase at larger incident angles as evidenced by indoor and outdoor experiments. Notably, outdoor testing consistently demonstrates the superior performance of upright SPs with a microprism sheet during the daytime, irrespective of the orientation of their faces.