PURPOSE: To reduce the cost of manufacture and improve durability and quality by dividing cover glass into two layers, i.e. a transparent substrate forming a solar battery and cover glass.

CONSTITUTION: A time display is made inside of an amorphous solar battery. The cover glass 1 and glass substrate 2 are set in a plastic packing 5 while forming a gap 4, and attached to a middle 6 with the plastic packing 5 interposed so that a radial clamping margin is left before the middle 6. The formation of the gap 4 eliminates the contacting between the cover glass and glass substrate and therefore causes no damage to the both to prevent the generation of interference fringes. An upper stage (a) and a lower stage (b) are provided to the inner wall of the plastic packing to prevent the cover glass from falling from the upper stage 5a during assembly. Further, the thickness of the glass substrate is made smaller than the height of the upper stage of the plastic packing, thus forming the gap 4.