Assessing Transient Thermal Models for Photovoltaic Modules Using High-Time-Resolution Outdoor Measurements

Accurate characterization of photovoltaic (PV) module temperature is essential for evaluating performance under real outdoor operating conditions. The widely used Faiman thermal model assumes steady-state behavior and neglects short-term temperature dynamics caused by rapid changes in irradiance, wind, and ambient conditions. As a result, temperature predictions based on steady-state assumptions can deviate from actual module behavior during rapidly changing environmental conditions. Recent studies have proposed transient extensions to such models by introducing thermal mass terms, highlighting the need for experimental validation under realistic outdoor operating conditions.

This work presents a measurement-focused study aimed at resolving transient temperature and irradiance effects on PV module efficiency using high time-resolution outdoor data. An outdoor measurement system is developed to simultaneously record module temperature, ambient conditions, irradiance, and electrical output under naturally varying environmental conditions. Attention is given to the transient response of different temperature sensing methods, including contact thermocouples and infrared-based measurements, and their influence on time-dependent thermal analysis and parameter interpretation.

Controlled experimental scenarios are designed to isolate key transient effects, including temperature response to ambient changes without irradiance, irradiance-driven heating near thermal equilibrium, and cooling behavior under shaded conditions while ambient conditions remain unchanged. These measurement configurations enable the identification of temperature lag and sensor response characteristics that can introduce non-negligible deviations in inferred thermal behavior when transient effects are neglected or insufficiently resolved.

The resulting time-dependent data are used to evaluate effective heat transfer behavior and to compare the performance and limitations of steady-state and transient thermal models. The analysis demonstrates clear differences between steady-state assumptions and observed transient behavior, particularly during periods of rapidly changing irradiance and ambient conditions. These differences are found to depend strongly on measurement methods, sensor response characteristics, and operating regime, underscoring the importance of sensor selection and temporal resolution in outdoor PV thermal studies.

Overall, this measurement-driven perspective provides experimental insight into the applicability of transient thermal models for PV systems under realistic outdoor operating conditions and offers practical guidance for improving temperature measurement strategies and system-level performance evaluation.