Experimental Yield Study of Bifacial PV Modules in Nordic Conditions

This study reports on the first full-year field study in Sweden using bifacial photovoltaic modules. The two test sites are located on flat roofs with a low albedo of 0.05 in Linköping (58°N) and were studied from December 2016 to November 2017. Site 1 has monofacial and bifacial modules with a 40° tilt facing south, which is optimal for annual energy yield for monofacial modules at this location. Site 2 has monofacial 40° tilt south-facing modules and bifacial vertical east-west orientated modules. The annual bifacial energy gain (BGE) was 5% at site 1 and 1% at site 2 for albedo 0.05. The difference in power temperature coefficients between bifacial and monofacial modules was estimated to influence BGE by +0.4 and +0.1 percentage points on site 1 and 2, respectively. A higher albedo could be investigated on a sunny day with fresh snow for the bifacial east-west modules. The specific yield was 7.57 kWh/kWp, which was a yield increase of 48% compared with tar paper at similar solar conditions.