Task 13 – Bifacial Photovoltaic Modules and Systems: Experience and Results from International Research and Pilot Applications (2021)

Main Authors:
Joshua S. Stein, Sandia National Laboratories, USA
Christian Reise, Fraunhofer ISE, Freiburg, Germany
Johanna Bonilla Castro, TÜV Rheinland, Cologne, Germany
Gabi Friesen, SUPSI, Switzerland
Giosuè Maugeri, RSE, Italy
Elías Urrejola, ATAMOSTEC, Chile
Samuli Ranta, TUAS, Finland


Bifacial photovoltaic cells, modules, and systems are rapidly overtaking the market share of monofacial PV technologies. This is happening due to new cell designs that have replaced opaque, monolithic back surface foil contacts with isolated contacts, which allow light to reach the cell from the rear side. Minor adjustments to cell processing steps have resulted in bifacial solar cells with rear side efficiencies from >60% to over 90% of the front side. Bifacial cells now come in many varieties (e.g., PERC+, n-PERT, HIT, etc.) and many cell lines have converted to producing bifacial cells. P-type solar cell limitations are driving the PV industry’s attention toward high efficiency n-type solar cells, including n-PERT solar cells, which are promising for two reasons: • Their process sequence calls for machinery that is generally compatible with current solar cell production lines. • The n-PERT cell concept permits very high bifaciality, up to 95% Today, busbar-less heterojunction (HJT) cells fabricated in a pilot-line on mass production equipment can reach efficiencies greater than 24%. With its high efficiency potential and lean manufacturing process flow, HJT cell technology is expected to gain greater global photovoltaic market share in the coming years. Even multijunction designs for bifacial cells are being considered. A multijunction bifacial cell based on a perovskite top cell and silicon HJT bottom cell appears promising…