Analysis of degradation and aging effects on polycrystalline silicon and thin-film PV modules operating outdoors under two US climates

This study investigates effects of aging and degradation on photovoltaic (PV) panels, by focusing on both polycrystalline silicon (p-Si) and thin-film technologies, specifically a-Si/ $\mu \mathrm{c}-\mathrm{Si}$ and CIGS. These modules were subjected to medium-term outdoor operation in two distinct climatic zones in the United States (US) over a three-year period. Findings indicate a slight decline in the performance for p -Si PV module, with an annual degradation rate (DR) of $1.01 \%$. The a-Si/ $/ \boldsymbol{c}$ c-Si thin-film technology exhibited an annual DR of $3.21 \%$, while CIGS PV panel indicated the highest annual DR with $6.53 \%$. We also evaluated annual DR of cardinal points coordinates of current-voltage (I=f(V)) curve. Furthermore, this study also examines the temporal evolution of Power Law Model (PLM) shape parameters with a view to predict long-term degradation of $\mathrm{I}=\mathrm{f}(\mathrm{V})$ and power-voltage (P=f(V)) curves, in the aim of achieving an in-depth investigation of long-term degradation of PV panels.