Patent ID: 8008572

Claim:
A photovoltaic module for converting radiation into electrical power, said module comprising: (a) a housing having a cavity of generally optimized closed shape inside said housing, said cavity having an internal surface area A s and including an opening or aperture for admitting said radiation into said cavity, said opening having an entrance aperture area A i that is substantially smaller than A s ; and (b) a plurality of single junction, or mufti-junction, or a combination of single and multi-junction photovoltaic cells within said cavity, at least some of said photovoltaic cells having different energy band-gaps to generate said electrical power in response to said radiation; and (c) a filter, associated with each photovoltaic cell, each filter tuned to the band gap of its associated photovoltaic cell comprising a Rugate filter or a combination of a stacked interference filter and a Rugate filter for admitting radiation corresponding to said band gap and reflecting radiation outside of said band gap, said reflected radiation being recycled within the cavity for conversion by cells having a corresponding band gap.