Model-T maker Henry Ford was fond of telling consumers they could have any color car, “so long as it was black.” Options in PV module choices used to be as limited, but that’s changing. Today, you can choose from three basic types of PV modules: monocrystalline, polycrystalline, and thin-film.
Most of us are familiar with the iridescent-blue faces of monocrystalline and polycrystalline modules. In both cases, fragile razor-thin wafers of silicon are embedded in a rigid frame and protected behind a layer of tempered glass. The difference between the two crystallines lies in the production of the cell. Monocrystalline ingots are extracted from melted silicon and then sawed into thin plates. Polycrystalline cells are created by pouring liquid silicon into blocks that are sawed into plates.
In the thin-film process, a silicon film (or other materials, such as cadmium telluride or copper indium gallium selenide) is deposited on glass or stainless steel, or within a flexible laminate. Although production costs are lower due to lower material costs, the efficiency of thin-film modules is typically about half that of either mono- or polycrystalline cells.