A photovoltaic cell, the cell comprising: a silicon substrate of bulk silicon material having front and rear surfaces; an emitter layer on the rear surface of said substrate; elongate channels through the emitter layer; elongate contacts to the bulk of the silicon substrate within at least some of the elongate channels, wherein the contacts are narrower than the channels; and gaps in the emitter between at least some of the elongate contacts and the emitter layer on the sides of the contacts.