TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Solar Cell: The principal layer comprises a base layer and a surface layer which is adjacent the first principal surface, is thinner than the base layer, is textured, and is more heavily doped than the base layer. The solar cell further comprises a passivation and anti-reflection layer conformally formed on the textured first principal surface. The first conductivity type is P-type. The base layer and the opposed layer have a total thickness of less than 100 microns. The total thickness is no more than 50 microns. The backside contact photovoltaic solar cell comprises: (a) a monocrystalline first film of silicon of a first conductivity type; (b) a second film of silicon of the first conductivity type, formed on the upper surface of the first film, and epitaxial, where first film of silicon is formed by autodoping during epitaxial with it; (c) a second film of silicon of a second conductivity type, formed in the lower surface of the first film, and epitaxial with it; (d) a first passivation film formed on the lower surface of the third film; (e) first openings through third film and the first passivation film; (f) contact regions formed in the lower surface of the first film, of the first conductivity type, more heavily doped than the first film, and aligned with the first openings; (g) first electrical contacts formed to each of the contact regions; (h) second openings through the first passivation film and spaced between the first openings; and (i) second electrical contacts to the third film formed through each of the second openings. The solar cell further comprises a monocrystalline silicon wafer of the second conductivity type more heavily doped than the first film and having a porous surface layer on which the second film is disposed and epitaxial with it. The solar cell further comprises a passivation and anti-reflection layer conformally coated on the textured upper surface of the second film. The combined thickness of the first, second, and third films and the passivation film is 30-100 microns. Preferred Method: In fabricating a backside contact solar cell, the wafer is of the first conductivity type more heavily doped than the first film and where the first deposition step causes autodoping to form a third film in the first film adjacent the porous layer which is more heavily doped than a remainder of the first film. The method further comprises exfoliating the films from the wafer. It further comprises texturing a surface of the first film. It also comprises depositing a passivation and anti-reflection layer on the textured surface. Fabricating a thin interdigitated backside contact photovoltaic solar cell on a thick wafer further comprises depositing conducting first contacts on top of the conducting layer and conducting second contact in second openings, where the first contacts are isolated from the second contacts. The first contact is connected together by a first bus bar and is interdigitated with the second contact, which is connected together by a second bus bar. The method also comprises cutting away portions of the first, second, and passivation layers on the side edges of the wafer. It further comprises: (i) clamping an upper surface of the solar cell with a wafer clamp; and (ii) separating at the porous layer the first and second layer and structure formed over it from the wafer in an exfoliation process. The exfoliation process comprises a mechanical fracturing process or a chemical etch process. The method further comprises texturing the third layer. It further comprises forming of a passivation and anti-reflection layer on top of the textured third layer. The porous layer is formed by electrochemical etching. It is smoothed by rapid thermal processing. Preferably, the conducting layer is aluminum.