The Yamada Lab of the Nagaoka University of Technology and Mitsubishi Rayon Co Ltd prototyped the "see-through prism-type concentrating PV," a photovoltaic (PV) cell module that collects sunlight with prisms.
The module has two characteristics. First, its output power per cell area is about 1.8 times higher, compared with the module without the prisms. Second, it can be used as window glass.
The PV cell module was prototyped by attaching PV cells on the surfaces of prisms and attaching them on a transparent substrate. The PV cells were made by cutting crystalline silicon PV cells manufactured by a company other than Mitsubishi Rayon.
When the module is vertically installed, much of the light that enters the module obliquely downward is totally reflected on the borders of the prisms, etc and led to the PV cells. In fact, when the module is seen obliquely downward, most area of the module seems to be covered by the cells even though the cells are actually arranged with some gaps.
On the other hand, when the module is seen head-on or obliquely upward, it can be seen through though some stripes are seen. This is because the prisms do not totally reflect light and the apparent sizes of the PV cells become smaller. Therefore, the module functions both as a low-cost concentrating PV cell module and as window glass at the same time.