To make these cadmium telluride cells, a thin layer of cadmium chloride is applied to the solar cell, and then heated up in a furnace.

Never place batteries or phones on or in heating phones, such as microwave ovens, stoves, or radiators. Batteries may explode when overheated.

They are solar cells, or photovoltaic cells, solar water heating, and solar furnaces (Darvill-S).