Development of thermo–electrical loss model for photovoltaic module with inhomogeneous temperature

Accurate, efficient, and reliable measurements of solar photovoltaic (PV) modules are essential for the evaluation and diagnosis of the actual operating status of PV plants. However, current online measurements and extraction models are limited because they do not account for power losses caused by inhomogeneous thermal performance of photovoltaic modules. Accordingly, this paper develops a coupled thermo–electrical loss model to access the power generation, energy losses, and degradation rate of photovoltaic modules with inhomogeneous temperature under actual operating conditions. The experiments indicate that the temperature coefficient of power dissipation and efficiency for solar cells with uneven temperature distribution PV modules are within −0.68W/oC to −0.83 W/°C and −0.46%/oC to −5.81%/oC, respectively. Additionally, the relative error values for the maximum power range from −2.54% to 4.09%, demonstrating the feasibility of the proposed model for predicting the power output behavior of operating PV modules with inhomogeneous temperature distributions. Furthermore, the daily performances of the modules indicate heat and electricity losses ranging from 0.245 kWh to 0.337 kWh, while the ratios of electrical energy dissipation to daily losses vary from 36% to 50%. To ensure the reliability of measuring degradation rates, the solar irradiance thresholds of PV module performance tests are nearly 632W/m2, 781W/m2, 875W/m2, and 875W/m2, respectively. Finally, for the long-term performance valuation, the levelized costs of electricity increase by approximately 0.011 CNY/kWh for every 5% reduction in annual power generation, and the PBP is extended by 4.81yr, 4.22yr, 3.62yr, and 7.10yr, respectively.