A polycrystalline module is made from polycrystalline semiconductor cells, while a monocrystalline module uses monocrystalline cells.

Producing monocrystalline silicon requires more energy than producing polycrystalline silicon, which means that the former is more expensive. However, monocrystalline cells have higher solar conversion efficiency compared to polycrystalline cells, while amorphous cells rank last. This translates into the size of the area occupied by the modules. Respectively, monocrystalline cells occupy the smallest area of those listed, so they require less money for the mounting structure and installation itself.

Polycrystalline cells are cut from blocks of polycrystalline silicon, so they are square in shape. Monocrystalline silicon is made with the Czochralski method to form a cylinder, which is then cut into wafers after milling the side edges. The substrate of a mono cell has a characteristic shape like a square with rounded off corners.

Monocrystalline cells are very dark blue, almost black – much darker than blue or navy polycrystalline cells.

From a performance standpoint, it does not make a significant difference. A photovoltaic generator of a certain capacity, regardless of the type of modules used – polycrystalline or monocrystalline – will produce almost the same amount of power per unit time. When choosing cell technology, programs that simulate the yield of PV installations usually do not distinguish between poly and monocrystalline modules, only between crystalline and amorphous. However, in recent years, more emphasis has been placed on the development of monocrystallisation technology, so these cells feature, among other things, improved temperature coefficients that contribute to the increased efficiency of monocrystalline PV modules.