A solar cell (2) is provided for generating alternating current to drive an external load (18) in response to light radiation. A central region (4) of given conductivity type is disposed between said first and second regions (6) and (8) of intrinsic or invertable semiconductor material applied with AC gate drive (12). The light-generated hole-electron pairs alternately diffuse in opposite directions across the alternately induced pn junctions between the central region (4) and the first and second converted conductivity type intrinsic or invertable regions (6) and (8) to set up alternating potential gradients in opposite directions.