Statistical Approach for Temperature Coefficients Evaluation of Highly Efficient PV Modules Tested in Northern Italy

The knowledge of temperature coefficients is fundamental to accurately assess the production of photovoltaic (PV) modules. This study proposes a comprehensive analytical approach for evaluating the temperature coefficients of maximum power for three commercial PV modules based on advanced technologies: Heterojunction (HJT), Tunnel Oxide Passivated Contact (TOPCon), and Interdigitated Back Contact (IBC). The analysis is based on data from a long-term outdoor experimental campaign conducted in Northern Italy between May 2024 and February 2025. A multistage methodology is employed, including the preprocessing of current-voltage curves. The temperature coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma$</tex> is analytically derived and its statistical distribution evaluated through the fitting of several theoretical probability density functions. A comparative performance metric as the Normalized Root Mean Square Error (NRMSE) is used to identify the most accurate distributions. The resulting modes are then compared with coefficients obtained by numerical optimizations and datasheet values. The results highlight that the HJT module exhibits the best temperature coefficient (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-0.26 \% /^{\circ} \mathrm{C}$</tex>) with respect to the IBC (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-0.29 \% /{ }^{\circ} \mathrm{C}$</tex>) and the TOPCon (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-0.32 \% /{ }^{\circ} \mathrm{C}$</tex>).