Rear contact solar cells achieve potentially higher efficiency by moving all or part of the front contact grids to the rear of the device. The higher efficiency potentially results from the reduced shading on the front of the cell and is especially useful in high current cells such as concentrators or large areas. There are several configurations.
Interdigitated back contact solar cells (IBC)
Rear contact solar cells eliminate shading losses altogether by putting both contacts on the rear of the cell. By using a thin solar cell made from high quality material, electron-hole pairs generated by light that is absorbed at the front surface can still be collected at the rear of the cell . Such cells are especially useful in concentrator applications where the effect of cell series resistance is greater.
An additional benefit is that cells with both contacts on the rear are easier to interconnect and can be placed closer together in the module since there is no need for a space between the cells.