The solar cell of embodiments includes a transparent first electrode, a photoelectric conversion layer mainly containing cuprous oxide on the first electrode, an n-type layer on the photoelectric conversion layer, and a transparent second electrode on the n-type layer. A mixed region or/and a mixed layer are present on the n-type layer side of the photoelectric conversion layer, and the mixed region and the mixed layer contain elements belonging to a first group, a second group, and a third group. The first group is one or more elements selected from the group consisting of Zn and Sn, the second group is one or more elements selected from the group consisting of Y, Sc, V, Cr, Mn, Fe, Ni, Zr, B, Al, Ga, Nb, Mo, Ti, F, Cl, Br, and I, and the third group is one or more elements selected from the group consisting of Ge and Si.

The solar cell of embodiments includes a transparent first electrode, a photoelectric conversion layer mainly containing cuprous oxide on the first electrode, an n-type layer on the photoelectric conversion layer, and a transparent second electrode on the n-type layer. A mixed region or/and a mixed layer are present on the n-type layer side of the photoelectric conversion layer, and the mixed region and the mixed layer contain elements belonging to a first group, a second group, and a third group. The first group is one or more elements selected from the group consisting of Zn and Sn, the second group is one or more elements selected from the group consisting of Y, Sc, V, Cr, Mn, Fe, Ni, Zr, B, Al, Ga, Nb, Mo, Ti, F, Cl, Br, and I, and the third group is one or more elements selected from the group consisting of Ge and Si.

A method of passive cooling for a high concentrating photovoltaic, the high concentrating photovoltaic, includes a photovoltaic receiver, a parabolic dish reflector and a plurality of thermally conductive heat pipes having a direct thermal contact between the receiver and the reflector to transfer excessive heat. The method includes receiving sunlight by the parabolic dish reflector, reflecting the sunlight towards the photovoltaic receiver that converts the sunlight into electricity and heat, transferring the heat through the thermally conductive heat pipes and absorbing the heat by the reflector serving a dual purpose as a heat sink. A reduction in weight and cost is accomplished by incorporating the flat heat pipes.

A method of passive cooling for a high concentrating photovoltaic, the high concentrating photovoltaic, includes a photovoltaic receiver, a parabolic dish reflector and a plurality of thermally conductive heat pipes having a direct thermal contact between the receiver and the reflector to transfer excessive heat. The method includes receiving sunlight by the parabolic dish reflector, reflecting the sunlight towards the photovoltaic receiver that converts the sunlight into electricity and heat, transferring the heat through the thermally conductive heat pipes and absorbing the heat by the reflector serving a dual purpose as a heat sink. A reduction in weight and cost is accomplished by incorporating the flat heat pipes.

A method of fabricating a solar cell assembly comprising a plurality of solar cells mounted on a flexible support, the support comprising a conductive layer on the top surface thereof divided into two electrically isolated portions—a first conductive portion and a second conductive portion. Each solar cell comprises a front surface, a rear surface, and a first contact on the rear surface and a second contact on the front surface. Each one of the plurality of solar cells is placed on the first conductive portion with the first contact electrically connected to the first conductive portion so that the solar cells are connected through the first conductive portion. A second contact of each solar cell is then connected to the second conductive portion by an interconnect. The two conductive portions serve as bus bars representing contacts of two different polarities of the solar cell assembly.

A method of fabricating a solar cell assembly comprising a plurality of solar cells mounted on a flexible support, the support comprising a conductive layer on the top surface thereof divided into two electrically isolated portions—a first conductive portion and a second conductive portion. Each solar cell comprises a front surface, a rear surface, and a first contact on the rear surface and a second contact on the front surface. Each one of the plurality of solar cells is placed on the first conductive portion with the first contact electrically connected to the first conductive portion so that the solar cells are connected through the first conductive portion. A second contact of each solar cell is then connected to the second conductive portion by an interconnect. The two conductive portions serve as bus bars representing contacts of two different polarities of the solar cell assembly.

A photovoltaic (“PV”) module may comprise an array of freeform micro-optics and an array of PV cells. The PV module may be a flat panel with a nominal thickness smaller than the length and width of the flat panel. An array of lenses may be embedded in an array substrate. The lenses may be coupled to light pipes. The lenses may concentrate light through the light pipes to multi-junction cells. Diffuse light may be transferred through the array substrate to a silicon cell. The lenses and light pipes may be manufactured using a molding and drawing process.

A photovoltaic (“PV”) module may comprise an array of freeform micro-optics and an array of PV cells. The PV module may be a flat panel with a nominal thickness smaller than the length and width of the flat panel. An array of lenses may be embedded in an array substrate. The lenses may be coupled to light pipes. The lenses may concentrate light through the light pipes to multi-junction cells. Diffuse light may be transferred through the array substrate to a silicon cell. The lenses and light pipes may be manufactured using a molding and drawing process.

A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode, which mainly contains a compound represented by Ga.sub.x1M1.sub.x2M2.sub.x3M3.sub.x4M4.sub.x5O.sub.x6, the M1 being Hf and/or Zr, the M2 being one or more selected from the group consisting of In, Ti, and Zn, the M3 being Al and/or B, the M4 is one or more selected from the group consisting of Sn, Si, and Ge, the x1, the x2, and the x6 being more than 0, the x3, the x4, and the x5 being 0 or more, and the x6 when a sum of the x1, the x2, the x3, the x4, and the x5 is 2 being 3.0 or more and 3.8 or less.

A multijunction solar cell including an upper first solar subcell having a first band gap and positioned for receiving an incoming light beam; a second solar subcell disposed below and adjacent to and lattice matched with said upper first solar subcell, and having a second band gap smaller than said first band gap; wherein the upper first solar subcell covers less than the entire upper surface of the second solar subcell, leaving an exposed portion of the second solar subcell that lies in the path of the incoming light beam.