A photovoltaic generator device for producing an output sufficient to turn on a MOS-gated device consists of a plurality of planar photogenerator cells connected in series. Each of the photovoltaic generator cells is contained on its own respective insulated tub. The insulated tubs are formed by wafer bonding a device wafer to a handle wafer with a dielectric isolation layer between them. Prior to joining the two wafers, a reflective layer is deposited on the surface of the device wafer to maximize absorption of incident light by the photogenerator cell. The individual tubs are isolated by trenches which enclose each tub and which extend through the reflective and to the dielectric layers between the device and handle wafers. Each tub is formed of an N.sup.- body having a shallow P.sup.+ diffusion. N.sup.+ contact regions are formed in the N.sup.- body and contact strips connect the devices of each of the tubs in series by connecting the P.sup.+ diffusions of one tub to the N.sup.+ contact of an adjacent tub. Alternatively, the isolation trenches are formed in the device wafer prior to bonding the two wafers, and the reflective layer is deposited on both the walls of the trenches and the surface of the device wafer to further increase light absorption.