Long term performance measurements and PV testing in a BIPV field test with different amounts of ventilation

PV integrated in the building envelope (BIPV) is seen as one of the key tracks to accelerate PV application in the built environment. However, integration might lead to decreased output and lifespan of PV modules due to less ventilation. To investigate this effect, a BIPV rooftop field test has been realized with 24 first generation Metallization Wrap Through (MWT) modules in 4 segments. The segments have different amounts of ventilation, ranging between forced and non-ventilated, and have been monitored for 3 years. In the non-ventilated segment, higher operating temperatures, higher daily temperature amplitudes and decrease in output have been measured, which increased over the monitoring period. At the end of the monitoring period, IV curves indicate a performance decrease between 7% and 60%, while EL images shows that the modules in the non-ventilated segment have more by-pass diode and cell failures. This study indicates the risk of failures in the investigated first generation MWT modules corresponding with typical damp heat and relative humidity cycle failures and indicates the value of long term field test measurements.