Outdoor Exposure Study on the Performance of Nine Different Types of Industrial PV Modules under 35° and under 90° Tilt

For practical and aesthetic reasons, solar PV modules with black instead of white backsheets or with colored front glass are used in vertical building integrated PV installations. This double use of area is favorable for societal acceptance that is ever more important with the raising number of PV installations. Besides, the variety of installation angles implies a broadening of the electricity generation profile which is indeed advantageous. However, these non-optimized orientations and the use of all-black and of colored modules under non-optimized orientation result in a lower yield compared to optimal PV systems with modules with white backsheet or even bifacial modules. This experimental study quantifies the yield reduction for using an exemplary blue colored versus a reference CIGS module and black instead of white backsheets in a comparison of two CIGS and seven up to date silicon PV modules of various technologies (Silicon heterojunction monofacial black and white backsheet, bifacial, PERC half cells black and white backsheet, shingled with black backsheet, PERC IBC with white backsheet) monitored in parallel under optimum tilt and 90° South orientation. We found that in May vertical installations show a specific yield reduced by 44 % compared to 35° tilted installations on average over all investigated monofacial technologies, and a gain of 4% in January. Modules with black backsheets installed vertically produced up to 7% less in May than their counterparts with white backsheets, this loss being up to 4% for 35° tilted modules. Also in May, the efficiency delta of 1%abs. between the CIGS module with blue-colored front glass and the reference resulted in a reduction of specific yield by 12% on the 90° tilted open rack. All these differences are less significant in winter. These numbers quantify the price to be paid for the advantages of customized non-optimum installations.