Blue shimmering solar cells usually act as foreign bodies in houses. Even printed modules for facades still have the appearance of colored glass panes. Researchers at the Institute for Solar Energy Research (ISFH) in Hameln have now developed a new process to inconspicuously insert PV modules into buildings (Paper). Their surface not only looks like stone – it is made of stone.
Stone veneer for the PV modules
To do this, the scientists either completely replaced the front panel of a commercially available PV module with a stone veneer, or they laminated a stone veneer onto the existing front panel. Modules can also be retrofitted in this way.
According to PV-Magazine consist of a total of 1.5 millimeter thin veneers made of fiberglass and a 0.5 millimeter thick stone layer. The rough stone surface also appears authentic to viewers who stand in front of the facade up close or who touch it, said lead author Arnaud Morlier to PV-Magazine.
However, the shading also halves the efficiency. Another problem: Depending on the grain and defects, the stone veneers only let light through unevenly – something that solar cells don’t like at all. As a remedy, the Hamelin-based company suggest scanning the light permeability of the laminate before assembly and only using the more homogeneous areas.
Facade modules make sense despite lower yield
If modules are mounted on a facade, the power yield decreases further compared to conventional roof modules because they are less well aligned to the sun. Nevertheless, they can be a useful addition to roof modules – for example because they provide more electricity in the morning and in the evening on east and west facades.
For the tests, a partner supplied thin layers of slate that can be easily peeled off. But what about customers who don’t have a slate facade, but a sandstone facade, for example? “Every stone is different,” says co-author Robert Wittek to TR. “We are already working on processes for other types of stone.” In the case of soft stones such as sandstone, for example, it is conceivable to grind it and place the grains in a resin bed. The people of Hamelin have also already experimented with wood. Follow-up projects are now intended to drive commercialization.