Electricity generation in the CIS module

Electricity from sunlight: The photovoltaic generation of an electric current in the CIS solar module.

Incident light is ‘absorbed’ by the CIS semiconductor and converted into electrical charge carriers. In order to create an electrical voltage, the positive and negative charges have to be separated. As in every solar cell, an electric field is used that forms between the CIS absorber and a suitable neighbouring layer. With CIS solar modules, this neighbouring layer consists of zinc oxide, which is a semiconductor. In order to connect the resulting voltage to a load and thus enable an electric current to flow, the absorber and zinc oxide must be equipped with electrical contacts. For this purpose, molybdenum metal is applied to the rear side of the module and a further layer of zinc oxide is applied to the front side that has been highly doped to make it conductive. Because zinc oxide is transparent, it lets the sunlight through to the absorber layer.

Pinstripes with a function: Integrated connection of stripe-shaped solar cells in series to form a module (schematic cross-section)

If a Soltecture solar module did not have any pinstripes, it would consist of a single square-metre-sized solar cell. It would generate so much electricity that a large part of the generated solar energy would immediately be lost again as heat. For this reason, Soltecture separates stripe-shaped solar cells from one another. If the individual solar cells are then connected together, this creates a module. To achieve this, the layers are engraved three times during the course of the module production, whereby the three lines are offset by around a tenth of a millimetre from one another and extend by different depths into the module stack. This results in a structure in which the molybdenum rear contact from one solar cell strip is connected to the zinc oxide front contact from the neighbouring solar cell.


If you would like to know more about how CIS modules work, how electricity is produced from sunlight and the purpose of the pinstripes, click here.