Most commercially economic solar cells today are made of silicon and are made up of either a crystalline or amorphous (Lacking a distinct crystalline structure) structure. Individual solar cells typically generate between .4 and .7 volts. They can be cut in size to meet specific applications. Since today’s solar cells using commercial materials are about 17% efficient in the conversion of sunlight, it takes a number of cells collectively to produce adequate power output. The individual cells are joined together in series or parallel to form a solar panel. The size of the panel is determined by the power requirements of the application and the efficiency of the solar cells.
The use of exotic materials for military and space applications can yield up to 40% efficiency in solar cell energy conversion though at a considerable cost. This presents significant opportunities for improvements in commercial products into the future.
The materials and processes used in solar panel construction have been well tested and have withstood the test of time. Most panels produced today are rugged and are expected to last up to 20-25 years in normal operations.