In the project “Shirkan” Fraunhofer ISE, together with its industrial partners, is developing the matrix technology. Here, we interconnect the shingle solar cells on the long cell side by a small overlap and laterally with an offset to each other, as in a masonry structure. This arrangement ensures the avoidance of inactive areas within the cell matrix, a uniform appearance and maximum area utilization.
In the project, we are optimizing various module concepts. In addition, a stringer is being developed that will achieve a maximum throughput of approx. 12000 shingle solar cells per hour in industrial production. First results of the shading behavior of a matrix shingle module show that - compared to a classical string shingle interconnection - between 70% and 95% more power is generated, depending on the scenario. This is especially true in the case of diagonal shading, e. g. by a chimney or a pile, and randomly distributed small-scale shading, e. g. by tree leaves. Simultaneous parallel and series connection of the solar cells allows the current to flow around the shaded area.
For industrial implementation, a reliable high-throughput shingle platform, a conductive adhesive and a novel curing process are being developed. In addition, the thermomechanical behavior of the joint and the long-term stability will be scientifically analyzed. The high potential of this interconnection topology will be demonstrated by designing and building the world's first full-format module with a cell-to-module efficiency loss of 0% (CTMη 100). Various designs of the applied cell matrix will demonstrate application in building-integrated photovoltaics.
The objectives in detail are:
- Development of a machine platform for matrix interconnection of shingle solar cells with a throughput of 12,000 shingle solar cells per hour and a precision for laser cutting of ± 25 µm/4σ and a deposition precision of ± 100 µm/3 σ with a cell overlap of < 1 mm.
- Development of a low-damage laser process for cell division
- Development of a conductive adhesive for the matrix interconnection of the shingle solar cells
- Development of an associated process technology for curing of the conductive adhesive
- Detailed analysis of the thermomechanical behavior of the joining area
- Construction of full-format PV modules (60-cell equivalent) with no inactive area within the cell matrix, exhibiting 0% cell-to-module efficiency loss (CTMη 100) and increasing module efficiency by > 1.5% compared to standard PV modules.
- Development of design rules for BIPV modules and build prototypes with attractive patterns and colored and transparent EVA/backsheet.
- Reliability tests (power loss < 5% according to TC and DH from IEC 61215) of the novel matrix interconnection topology.