Abstract: A solar cell is described. The solar cell is fabricated on a substrate, the substrate having a front surface and a back surface. The substrate includes, at the front surface, a first region having a first global thickness and a second region having a second global thickness. The second global thickness is greater than the first global thickness. A plurality of alternating n-type and p-type doped regions is disposed at the back surface of the substrate.

Abstract: A solar cell includes negative metal contact fingers electrically connected to N-type diffusion regions of the solar cell and positive metal contact fingers electrically connected to P-type diffusion regions of the solar cell. Both the N-type and P-type diffusion regions are on the backside of the solar cell. The solar cell includes a front side that faces the sun during normal operation. The negative and positive metal contact fingers may be interdigitated. For increased solar radiation collection, the metal contact fingers may be arranged to point to and collectively cover portions of a perimeter of a solder pad. For example, the negative metal contact fingers may be arranged to point to and collectively cover two or three sides of a solder pad.

Abstract: In one embodiment, a solar cell has base and emitter diffusion regions formed on the back side. The emitter diffusion region is configured to collect minority charge carriers in the solar cell, while the base diffusion region is configured to collect majority charge carriers. The emitter diffusion region may be a continuous region separating the base diffusion regions. Each of the base diffusion regions may have a reduced area to decrease minority charge carrier recombination losses without substantially increasing series resistance losses due to lateral flow of majority charge carriers. Each of the base diffusion regions may have a dot shape, for example.

Abstract: In one embodiment, active diffusion junctions of a solar cell are formed by diffusing dopants from dopant sources selectively deposited on the back side of a wafer. The dopant sources may be selectively deposited using a printing method, for example. Multiple dopant sources may be employed to form active diffusion regions of varying doping levels. For example, three or four active diffusion regions may be fabricated to optimize the silicon/dielectric, silicon/metal, or both interfaces of a solar cell. The front side of the wafer may be textured prior to forming the dopant sources using a texturing process that minimizes removal of wafer material. Openings to allow metal gridlines to be connected to the active diffusion junctions may be formed using a self-aligned contact opening etch process to minimize the effects of misalignments.

Abstract: In one embodiment, harmful solar cell polarization is prevented or minimized by providing a conductive path that bleeds charge from a front side of a solar cell to the bulk of a wafer. The conductive path may include patterned holes in a dielectric passivation layer, a conductive anti-reflective coating, or layers of conductive material formed on the top or bottom surface of an anti-reflective coating, for example. Harmful solar cell polarization may also be prevented by biasing a region of a solar cell module on the front side of the solar cell.