From sphere to hemisphere: secondary optics for micro-CPV modules

The paper considers secondary concentrating elements of the full sphere (glass ball)-truncated sphere-hemisphere form factor for the micro-CPV module system with primary focusing optics of the biconvex short-focus lens type. It is shown that the maximum average radiation concentration factor in the focal spot is achieved using a truncated sphere with a minimum diameter, but at a relatively large distance from the primary concentrator to the radiation receiver. Increasing the sphere diameter while simultaneously decreasing the average radiation concentration factor in the focal spot allows reducing the specified distance, i.e. the overall height of the micro-CPV module.