The German Fraunhofer Institute for Solar Energy Systems ISE in Freiburg has developed a special adhesive process to interconnect silicon solar cells for the industrial production of shingle modules. According to the scientists, »the market demand for shingle modules is rising rapidly due to their high efficiency and pleasing aesthetics.«
Due to mechanical stresses, shingle cells cannot be soldered like conventional cells. »Now with the adhesive technology, it has become possible to manufacture reliable and robust shingle cell strings. The adhesive not only balances out the thermal expansion of the glass caused by varying ambient temperatures, but also is lead-free.«
Through shingling, the gaps between the cells disappear, maximizing the possible module area used for electricity production and giving the module a homogeneous, aesthetic appearance. The higher efficiency of shingle, as compared to conventional, modules is due, for one, to the larger active area of the module and secondly since the shadow losses caused by conventional surface-mounted cell interconnectors are avoided. The resistance losses are also less because of the lower current densities in the cell stripes.
Power measurements at the calibration laboratory CalLab PV Modules of Fraunhofer ISE confirmed, that shingle modules »have module efficiencies that are approximately 2 percent (absolute) higher than conventional modules with the same cell efficiency.«
»The aesthetics and the high power density will push the shingle technology forward, especially in the automotive industry and for building-integrated applications,« said Achim Kraft, head of team Interconnection Technologies at Fraunhofer ISE. »European module manufacturers inquire increasingly about application-oriented developments and technology assessments for shingle solar cells.«