Solar cell module

A photovoltaic module comprising:

• (A) a first independently operable panel of solar cells having a first bandgap and including a first optically transparent substrate having a plurality of thin film solar cells formed thereon, at least some of said thin film solar cells being electrically series interconnected;
• (B) a first transparent conductive layer between said first substrate and said thin film solar cells and a second transparent conductive layer on the other side of said thin film solar cells;
• (C) a second independently operable panel of solar cells having a second bandgap, said first and second band gaps being different, said second panel including a second substrate carrying a plurality of solar cells, at least some of said solar cells on said second substrate being electrically series interconnected;
• (D) said second transparent conductive layer having a thickness such that the light passed through it is optimally at the peak of the spectral response of the semiconductor material in said second panel of solar cells;
• (E) said first and second panels being stacked one on top of the other with said solar cells facing each other in optical series;
• and
• (F) an interface layer of optically transparent and electrically insulative material sandwiched between said first and second panels.