Less ugly solar cell panels for building integration

In a EUDP sponsored research project, called Black Silicon, IPU and DTU Fotonics/Nanolab – together with three commercial partners – have developed both a method to deposit a black inorganic coating on the metal strings used in solar cells and a black silicon surface suitable for solar cell production. Following up on these results in a proof-of-concept grant from DTU, a semi-automatic machine has been developed for coating of the metal strings. The shiny metal strings are the ones that conducs the current from the cells, and they are also responsible for the electrical connections between the 60 cells that a standard solar cell panel consists of. The strings are attached to the cells by soldering, and the normal metal strings are shiny because they are coated with the soldering alloy (tin-lead-silver).

By depositing a black inorganic coating of both sides of the metal strings, a more aesthetic look is possible – particularly if the well-known blueish silicon surface is also replaced with black silicon. It is very important that the black coating is durable, since 20 to 30 years of warranty is common in the solar panel marked. After the strings have been coloured black on both sides, 156 mm wide areas alternating between the top and bottom of the string, are cleaned with a mild blasting process. This is necessary in order to have a clean surface for soldering.