Comprehensive analysis and insights into the relationship between temperature coefficients, PV failures, and investigating their correlation with other PV parameters

Abstract

Ensuring long-term performance and reliability of photovoltaic (PV) modules is essential for minimizing maintenance costs and supporting large-scale solar deployment — particularly in regions like Algeria, where solar energy plays a key role in national energy transition strategies. Among the key performance indicators, temperature coefficients (TCs) offer valuable insights into how PV parameters respond to temperature changes. While TCs are routinely included in manufacturer datasheets, their potential use as diagnostic tools for identifying and understanding failure mechanisms remains insufficiently explored. This work presents a comprehensive analysis of the relationship between temperature coefficients and PV module degradation, with a focus on enhancing failure detection and performance evaluation. Five PV module types, exposed to real outdoor conditions under Mediterranean climatic conditions for periods ranging from 4 to 30 years, were investigated through a series of inspections conducted in accordance with IEC 61215 and related standards. These included visual and thermal inspections, (I–V) curve measurements, electrical parameter assessments, and internal resistance evaluations. Furthermore, new differential ratios are introduced to improve comparative analysis. The analysis emphasizes three key datasheet-provided TCs: maximum power ($T{C}_{P_{max}}$), open-circuit voltage ($T{C}_{V_{oc}}$), and short-circuit current ($T{C}_{I_{sc}}$), while also drawing insights into derived coefficients such as maximum voltage ($T{C}_{V_{mpp}}$), maximum current ($T{C}_{I_{mpp}}$), and fill factor ($T{C}_{FF}$). Results reveal that both optical (e.g., discoloration, delamination) and non-optical (e.g., hot spots, corrosion) failures influence TC behavior. In particular, $T{C}_{P_{max}}$ shows strong sensitivity to failure occurrence and distribution, while $T{C}_{V_{oc}}$ closely correlates with observed thermal distribution. Although $T{C}_{I_{sc}}$ shows higher measurement uncertainty under outdoor conditions, its degradation appears linked to optical failure. The findings suggest that TCs, beyond their conventional use, can serve as practical indicators of specific degradation mechanisms, offering a complementary or alternative approach to existing failure detection or diagnostic techniques. The paper also recommends that manufacturers expand datasheet specifications to include additional temperature coefficients (TCs) to enhance PV module failure detection and enable more accurate performance comparisons. The paper also recommends that manufacturers expand datasheet specifications to include additional TCs for enhanced PV module failure detection and TCs values comparison. Future work will aim to refine this methodology through expanded datasets and more precise uncertainty quantification under varying environmental conditions.