Investigation of the power generation of organic photovoltaic modules connected to the power grid for more than three years

In this paper, we report on the power generation of commercial organic photovoltaic (OPV) modules installed outdoors at the Kyushu Center, National Institute of Advanced Industrial Science and Technology for more than three years. The OPV modules were connected to a power conditioner system together with crystalline Si, hydrogenated amorphous Si, and Cu(In, Ga)Se-2 photovoltaic (PV) modules. We investigated the output power degradation of the commercial OPV and other PV modules due to aging. We found that there are three distinctive changes in the output power of the OPV modules: (1) rapid initial degradation, (2) gradual secondary degradation, and (3) seasonal variation. We believe that the seasonal variation is due to the metastability of the solar cells. We analyzed the output power behavior in detail based on the current-voltage (I-V) characteristics and we compared the outdoor and indoor measurements. We also found that the change in I-V characteristics of the OPV modules due to light soaking are reversible. (c) 2019 The Japan Society of Applied Physics