Assessment of Personal Safety Concerns of Plug and Play Photovoltaic Inverters using a Black Box Approach and Laboratory Measurements

The increasing use of plug and play photovoltaic systems has raised concerns about their safety, especially with nonprofessional installations, which existing standards only partially address. This study proposes a black box testing approach to assess the personal safety of plug and play inverters. A total of 25 microinverters are assessed using three tests: (1) analyzing the residual voltage at the mains plug after disconnection, (2) the feed-in current increase under low grid voltage conditions, and (3) the maximum touch temperature during operation. Residual voltage testing reveals that 56% of the inverters comply with the limit of the latest official German plug and play system standard draft and behave similarly to other tested electrical devices. Further investigation is required to determine if exceeding this limit presents a direct safety risk. However, adding a relay was identified as an effective measure to ensure compliance. Under low voltage conditions, current increases up to 26.3% were measured, potentially stressing nondedicated circuits. In the temperature test, a positive correlation between the inverters power density and the touch temperature was found. The findings of this analysis provide insights for future standardization efforts and offer guidance to manufacturers in improving the safety of these PV systems. This is an open access article under the terms of the Creative Commons Attribution License, which permits use and distribution in any medium, provided the original work is properly cited.