Thin-Film Solar Modules

Principal buildup of thin-film solar modules

Thin-film solar cells are generated by coating a substrate, e.g. a glass panel with layers of conductive and semi-conductive materials of a few micrometers in thickness.

The individual layers of material are deposited by various processes. After each coating step, the particular layer is divided into basic structures of thin strips of material for series connection to the layers of the completed solar cell module. This layered connection process to the modules thus becomes part of the production chain.

Laser scribing as well as mechanical or chemical treatments are common methods for separating conductive and semi-conductive layers for the subsequent series connection of a solar module. A comparison of these various treatment methods shows that laser scribing guarantees the highest productivity and precision.

For transparent conductive oxides (TCO = transparent conductive oxide) predominantly zinc-oxide (ZnO) or tin-oxide (SnO2) are applied. For semi-conductive materials, the following substances have been found to be suitable for industrial uses:

• amorphous silicon (a-Si)
• amorphous and micro-crystalline silicon (a-Si / µSi)
• cadmium telluride (CdTe)
• copper-indium diselenite (CIS)

The rear electrodes consist of metallic layers such as molybdenum for example.