A composition for solar cell electrodes includes a silver powder, a glass frit containing silver, tellurium and zinc, and an organic vehicle, wherein the glass frit has a mole ratio of Ag to Te ranging from about 1:0. The oven module has an enclosure to accommodate the component and a heating element. The device includes a first bar with bearing surfaces for the goods to be cooled, which bar is tiltably attached to the frame. The guide shaft is coupled to the first seat portion and inserted into the first bearing portion. Alternatively, the output movable mirrors of the optical switch are separated into a plurality of areas to be arranged, and are arranged in each area so that the path switchover between two output movable mirrors is performed without the optical signal crossing other output movable mirrors. The piston is shiftable between a front position close to the intake opening and a rear position close to the vent hole such that as the liquid lubricant fills the lubricant compartment the piston moves into the rear position.