The BiZePS‑Plus project, coordinated by Fraunhofer‑ISE, aimed to advance measurement techniques for highly bifacial solar cells, both busbarless and shingle‑type, and to establish standards that enable rapid, accurate assessment of cell performance and sorting for module integration. The work focused on developing an inline measurement system (AP2) that can simultaneously illuminate the front and rear surfaces of a cell, thereby capturing true bifaciality and fill‑factor variations that arise during manufacturing. By optimizing contact layouts for busbarless cells, the team produced a calibration procedure that reduces measurement uncertainty and allows quantitative comparison of cells with different metallization schemes. The system also incorporates a new hysteresis‑correction algorithm tailored to high‑capacitance bifacial cells, enabling measurement times of less than 10 ms for silicon heterojunction (SHJ) cells while maintaining accuracy.

Automation of the measurement process for bifacial shingle cells (AP2.2) was achieved, allowing high‑throughput testing of large cell batches. An analysis methodology for wafer‑bonded bifacial shingle cells (AP2.3) was established through both small‑scale laboratory experiments and large‑scale industrial trials. These experiments fed into predictive models that estimate module performance based on cell‑level data. Separating front‑side and rear‑side effects (AP2.4) was accomplished by combining IV‑curve analysis with spectral‑response measurements, providing a clear view of recombination losses on each side of the cell. The new hysteresis‑correction method (AP2.5) was validated against standard SHJ and PERC cells, demonstrating its applicability across different cell technologies.

For module integration, the project developed sorting methods (AP3) that use inline analysis of highly bifacial cells to group cells with similar performance characteristics. This sorting improves module yield and enables targeted process optimization. A high‑efficiency wafer‑marking technique was introduced for the HEVEL cell process, facilitating precise cell identification during module assembly. Although the planned module build was not carried out due to the withdrawal of partner HEVEL, the data collected from the HEVEL cell charge already indicated that the high performance homogeneity of the cells would not benefit significantly from additional sorting, a finding that guided the project’s final focus on performance prediction for shingle cells.

The collaboration involved Fraunhofer‑ISE as the coordinating institute, h.a.l.m. elektronik GmbH, Jonas&Redmann GmbH, and Hevel Energy Group LLC (until March 2022). The project ran from 1 July 2020 to 31 December 2022 and was funded by the German Federal Ministry of Economics and Energy under grant number 03EE1064. Dr. Stefan Rein served as project leader, with Dr. Nico Wöhrle as deputy. Reporting authors included Stefan Rein, Nico Wöhrle, Johannes Greulich, Alexander Krieg, Tobias Kemmer, Michael Rauer, and Jochen Hohl‑Ebinger. The project’s outcomes contribute to the broader effort to standardize measurement practices for busbarless and bifacial shingle cells, thereby supporting the rapid deployment of bifacial modules that can deliver higher energy yields with the same resource input.