The world’s first bifacial PV noise barrier plant on a railway line went online end of 2008 in Münsingen, Switzerland. 2009 the PV plant was fully equipped with measurement instruments in order to monitor functionality of the bifacial PV noise barrier plant during first years of operation, evaluate performance, overall energy production and influence of shading on bifacial PV plants. A focus of investigation was on shading effects on an operating bifacial PV plant, especially caused by railway infrastructure.
A maximum performance of up to 75% was measured, leading to a total energy production of 5’076 kWh in 2010 and 5’339 kWh in 2011 with very similar solar irradiation in these years which were about 13% below simulation-based expected solar irradiation for Münsingen. With a nominal power on the front side of the bifacial modules of 7.25 kWp this leads to a specific performance of 700…736 kWh/kWp. Corrected to average solar irradiation this leads to a specific performance of 790…830 kWh/kWp. This is still less than the expected 931 kWh/kWp.
Shading of one string during morning hours leads to a reduction of energy production of 60% during the shaded morning hours for this string. For the overall energy production of the plant, this corresponds to a reduction of slightly more than 5%. Further reduction is due to inverter sizing and efficiency, which is partially due to unequal front and back side nominal power of the bifacial modules. Optimal front-to-back-ratio of the bifacial modules and inverter sizing is accountable will presumably lead to another 5…8% additional energy production.
The overall performance of the bifacial PV noise barrier plant in Münsingen is good so far, although there is some potential for further improvement.
