Solar Cells and Modules

Solar Cells

A solar cell or photovoltaic cell is a semiconductor device that converts light directly into electricity by the photovoltaic effect.

There are different types of photovoltaic cells:

Single crystal silicon PV cells are manufactured using a single-crystal growth method and have commercial efficiencies between 15 % and 18 %.

Multicrystalline silicon cells, usually manufactured from a melting and solidification process, are less expensive to produce but are marginally less efficient, with conversion efficiencies around 14 %.

PV cells made from silicon ribbons demonstrate an average efficiency around 14 %.

Thin film cells, constructed by depositing extremely thin layers of photovoltaic semi-conductor materials onto a backing material such as glass, stainless steel or plastic, show stable efficiencies in the range of 7 % to 13 %. Thin film materials commercially used are amorphous silicon (a-Si), cadmium telluride (CdTe), and copper-indium-gallium-diselenide (CIGS).

Commercially available thin film modules:

• Are potentially cheaper to manufacture than crystalline cells
• Have a wider customer appeal as design elements due to their homogeneous appearance
• Present disadvantages, such as low-conversion efficiencies and requiring larger areas of PV arrays and more material (cables, support structures) to produce the same amount of electricity

Source: IEA PVPS

Solar Modules

A solar module (also called solar panel) is a commercial product composed of solar cells.

Solar modules are rated in peak watts [Wp] according to their output under optimal outdoor conditions. Thus, a 50 Wp module can be expected to supply 50 W of power in full sunshine. The performance is reduced by high temperatures. The modules are connected in series and/or in parallel depending on the system requirements. A serial connection increases the voltage, a parallel connection increases the current.