Performance and dye-stability of semi-transparent dye-sensitized solar cell pavilion modules after six years of operation

A solar pavilion with 248 commercial 30 × 30 cm semi-transparent DSC modules were built at Roskilde University campus in 2016. After five years of operation under Danish climate conditions, and again one year later, two representative modules one from the south side and one from the north side of the pavilion facades were removed and their electrical performance relative to new modules was obtained. In addition, the respective dye degradation and triiodide bleaching was investigated. The south oriented module showed a decrease in efficiency of 85% and the north oriented module of 34% after 5 years. The degradation products of the applied ruthenium dye Z907 were typical thermal degradation products in which one or both of the thiocyanate ligands in Z907 had been substituted with the electrolyte components 3-methoxypropionitrile and or iodide. The degree of dye degradation in the south and north oriented modules after five years were 73% and 50% and the I₃⁻ concentration decreased 63% and 33%, respectively. The decrease in electrical performance Δη = 16%/year of the south module is within the same magnitude as performance loss of similar large-scale outdoor DSC installations. Such relatively high efficiency losses pr. year needs to be reduced if building integration photovoltaics based on the dye-sensitized solar cell technology should be commercially successful.