Heterojunction solar cells combine two different technologies into one cell: a crystalline silicon cell sandwiched between two layers of amorphous “thin-film” silicon. This allows an increase in the efficiency of the panels and more energy to be harvested easily when compared to conventional silicon solar panels. The most common type of solar panels is made with crystalline silicon – either monocrystalline or polycrystalline. Amorphous silicon is thin-film silicon unlike crystalline silicon, amorphous silicon does not have a regular crystalline structure. Instead, the silicon atoms are randomly ordered. As a result, manufacturing this type of solar cell is less expensive.

This lower cost and flexibility in the type of materials that amorphous silicon can be deposited on are a couple of important advantages. With heterojunction solar cells, a conventional crystalline silicon wafer has amorphous silicon deposited on its front and back surfaces. This results in a couple of layers of thin-film solar that absorb extra photons that would otherwise not get captured by the middle crystalline silicon wafer.