A measurement method of subcell photocurrents and a matching degree of the subcell photocurrents of a multi-junction photovoltaic cell is provided. The measurement method includes measuring an I-V characteristic of the multi-junction photovoltaic cell; and measuring currents corresponding to respective current steps in an I-V curve to obtain approximate values of short-circuit currents of subcells in the multi-junction photovoltaic cell, and then calculating a mismatching degree of the multi-junction photovoltaic cell using step currents. According to the measurement method, a current mismatching degree of the multi-junction photovoltaic cell is obtained by calculating the mismatching degree of the step currents occurring in the I-V curve. The measurement method is rapid and simple, the measurement method avoids complicated and time-consuming processes where the subcell photocurrents are calculated based on a standard light source spectrum integral with bias lights applied.

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 photovoltaic device and method for fabrication include multijunction cells, each cell having a material grown independently from the other and including different band gap energies. An interface is disposed between the cells and configured to wafer bond the cells wherein the cells are configured to be adjacent without regard to lattice mismatch.

A photovoltaic device and method for fabrication include multijunction cells, each cell having a material grown independently from the other and including different band gap energies. An interface is disposed between the cells and configured to wafer bond the cells wherein the cells are configured to be adjacent without regard to lattice mismatch.

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.

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.

A solar cell of an embodiment includes: a p-electrode in which a first p-electrode and a second p-electrode are laminated; a p-type light-absorbing layer in direct contact with the first p-electrode; an n-type layer in direct contact with the p-type light-absorbing layer; and an n-electrode. The first p-electrode is disposed between the p-type light-absorbing layer and the second p-electrode. The p-type light-absorbing layer is disposed between the n-type layer and the first p-electrode. The n-type layer is disposed between the p-type light-absorbing layer and the n-electrode. The first p-electrode includes a metal oxide containing Sn as a main component.

A solar cell of an embodiment includes: a p-electrode in which a first p-electrode and a second p-electrode are laminated; a p-type light-absorbing layer in direct contact with the first p-electrode; an n-type layer in direct contact with the p-type light-absorbing layer; and an n-electrode. The first p-electrode is disposed between the p-type light-absorbing layer and the second p-electrode. The p-type light-absorbing layer is disposed between the n-type layer and the first p-electrode. The n-type layer is disposed between the p-type light-absorbing layer and the n-electrode. The first p-electrode includes a metal oxide containing Sn as a main component.

A method of fabricating a four junction solar cell having an upper first solar subcell composed of a semiconductor material including aluminum and having a first band gap; a second solar subcell adjacent to said first solar subcell and composed of a semiconductor material having a second band gap smaller than the first band gap and being lattice matched with the upper first solar subcell; a third solar subcell adjacent to said second solar subcell and composed of a semiconductor material having a third band gap smaller than the second band gap and being lattice matched with the second solar subcell; and a fourth solar subcell adjacent to and lattice matched with said third solar subcell and composed of a semiconductor material having a fourth band gap smaller than the third band gap; wherein the fourth subcell has a direct bandgap of greater than 0.75 eV.