Abstract: The invention provides photovoltaic concentrator solar cells and a method of forming these from a semiconductor wafer. The method has the steps of first doping the rear surface of said wafer so as to provide a first doped region. Depositing passivation layers on the front and rear surfaces. Forming a deep groove in the rear surface through the passivation layer and doping said rear surface so as to provide an oppositely doped second doped region in the deep groove. Then an opening is formed through the rear passivation layer to the first doped region; and electrical contacts are formed on the rear surface to electrically connect to the first and second doped regions. The photovoltaic concentrator solar cell has a semiconductor wafer with a passivation layer deposited on front and rear surfaces; and a first doped region at the rear surface.