Reflectance-reducing covers for solar cells

The performance of a solar array can be improved by reducing its reflectivity with a reflectance-reducing glass cover. The performance of such a reflection-reducing cover on a planar solar cell is calculated by a ray-tracing computer model. Light reflected from the surface of the cell is totally internally reflected within the glass cover by the angled facets, and hence is redirected back to the cell surface. This allows reduced reflection to be achieved on a planar surface cell. A variety of wedge angles and geometrical configurations were investigated. The number of passes of light within the cover was calculated, verifying that use of the cover reduces the surface reflectivity of an AR-coated planar cell, and the performance was calculated for normally incident and off-angle illumination. Sensitivity of the reflectance to off-normal light is important for nontracking arrays, for collection of diffuse illumination and for concentrator cells. The angle sensitivity is dependent on whether the light incident angle is parallel or perpendicular to the groove direction. The reflectivity of arrays with reflectance-reducing glass is lower than with planar glass even for off-normal incidence.