A photovoltaic device in a semiconductor substrate, has a radiation receiving front surface and a rear surface, a first region of one conductivity type (29), and a second region with the opposite conductivity type (20) adjacent to the front surface, and an antireflection layer (27). The rear surface is covered by a dielectric layer (39) covering also an inside surface of the via. The front surface has current collecting conductive contacts (23) and the rear surface has conductive contacts (31) extending through the said dielectric. A conductive path is provided in the via for photogenerated current from the front surface. By having the dielectric all over, no aligning and masking is needed, and the same dielectric serves to insulate, provide thermal protection for the semiconductor, and helps in surface and bulk passivation. It also avoids the need for a junction region near the via, hence reducing unwanted recombination currents.