2023 Volume 49 Issue 2 Pages 55-63
In this paper, an equivalent circuit between PV module/string and the ground is proposed. This equivalent circuit consists of one insulation resistance and five RC-components, which has one resistance and one capacitance in series, in parallel. This proposal has been justified by in-depth integrated discussion of experimental and theoretical approaches with 8-series PV module string. It is obvious that the equivalent circuit of PV module string can be obtained by parallel combination of circuit components of each PV module. The five RC-components, which PV module intrinsically belongs to, have different time constants, from 10-2 to 102 sec. The insulation resistance and some RC-components with longer time constant are strongly affected by absolute humidity: resistance drops but capacitance rises in accordance with increase in the absolute humidity. But the other RC-components are insensitive to the absolute humidity. The result described in this paper may be helpful for engineering discussion on various electrical safety issue on photovoltaic power generation plants such as ground fault and electrical shock.
