Abstract: Semiconductor switching elements (inverse-parallel connected thyristors) of each main circuit element unit are connected in parallel to a main contact of an electromagnetic contactor. An operation input voltage signal applied to an electromagnetic coil of the electromagnetic contactor is detected by an input-voltage detecting circuit of a control section. When the electromagnetic contactor is closed and opened, a one-shot-pulse generating unit outputs a one-shot pulse based on an output of the input-voltage detecting circuit and a signal indicating an opening/closing state of an auxiliary normally-closed contact of the electromagnetic contactor. The semiconductor switching elements are made on only for a short time by a firing circuit based on the one-shot pulse, to turn on and off a load current.

Abstract: A method of manufacturing a high efficiency solar battery and a high efficiency solar battery comprising a transparent electrode of SnO.sub.2, and a semiconductor layer and a metal electrode formed on the transparent electrode in the stated order. The surface unevenness of the transparent electrode is controlled by forming a dual layer structure. The layer adjacent the transparent substrate comprises an undoped SnO.sub.2 layer, having crystal grains growing substantially perpendicular to the substrate, producing an uneven surface. A doped layer containing impurities, such as F, Cl, and Sb is deposited over the undoped layer.