Performance modeling of PVT collectors: Implementation, validation and parameter identification approach using TRNSYS

Photovoltaic-thermal (PVT) collectors are hybrid solutions for the conversion of solar energy into electrical and thermal energy. The development of validated and standardized PVT collector models is important for the comparison of products, informed decision making based on energetic and economic performance, and to promote the market diffusion of PVT technology. This contribution presents a novel PVT performance model, compares different parameter identification approaches, and validates the model and its implementation in a common simulation software (TRNSYS) for system simulations. For the thermal performance model, a two-node model with either one or two thermal capacities is compared. The two-node approach with one thermal capacity represents an extension of the quasi-dynamic solar thermal collector model with the added functionality of the electrical performance. This modeling approach has also proven to be the recommended modeling approach for the investigated PVT collectors in this work. Furthermore, the parameter identification procedure is described in detail and different approaches are compared. It is shown that a combined identification of thermal and electrical model parameters with determination of all thermal and electrical model parameters is the most suitable approach regarding accuracy and processing effort. To sum up, the presented PVT performance model and the proposed parameter identification procedure achieve a good agreement of simulated and measured thermal and electrical power output for the analyzed PVT collector types and operating conditions. Hence, the model is suitable for dynamic simulation studies and is proposed as standardized performance model for PVT collectors.