As
a clean and renewable energy, solar energy has drawn people’s
attention to mitigate the energy crisis around the world. A solar
photovoltaic (PV) system is a reliable way to collect solar energy
whose service lifetime is usually shorter than the designed time because
of accumulated charge-induced degradation caused by electrical aging.
With the rapid development of PV systems, the traditional polyethylene
terephthalate (PET) backsheet cannot meet the requirements of insulation
and package for the advanced solar energy system. In this context,
two different backsheet materials, namely, KPK (polyvinylidene fluoride,
PET, polyvinylidene fluoride) and TPT (polyvinyl fluoride, PET, polyvinyl
fluoride), were selected to explore accumulated charge-induced degradation
caused by partial discharge (PD) and corona discharge. In this paper,
the backsheets were electrically stressed for 30, 60, and 120 min
by PD and electrically stressed for 10 min by corona discharge. The
accumulation and transportation of charges were investigated by phase-resolved
partial discharge (PRPD) and surface potential decay (SPD). At the
same time, the topography of KPK and TPT determined using atomic force
microscopy after PD activity was also investigated. The explorations
of PD activity showed that KPK and TPT have a similar PD resistance,
but their SPD were entirely different after corona discharge. The
research works in this paper provide an important path to investigate
the aging process of insulating polymers and evaluate the lifetime
of insulating backsheets of PV modules, as well as a guidance to improve
the testing standards for the PV system.