Abstract: The invention contemplates a sealed electrical-meter construction for measuring an electrical quantity such as an electrical resistance, and having particular application to the display of liquid-level where measured resistance is a function of observed liquid level. The meter construction provides a transparent side port at which a solar-cell assembly is exposed to external light, and the voltage output of the cell, after reduction to assure constant-voltage level is used to power the measuring circuit. Fiber-optics elements at the transparent side port convey light to the display face of the meter, so that even a flashlight at nighttime is sufficient to excite the solar-cell assembly and illuminate the display face.