Dynamic numerical model of a high efficiency PV–T collector integrated into a domestic hot water system

• A high accuracy 3D and dynamic model of PV–T collector has been developed.
• Mismatch effects due to PV cells temperatures are taking into account.
• Exchanger geometry and real fluid path are implemented.
• The PV–T model is validated through steady-state and dynamic regimes.

A Photovoltaic–Thermal (PV–T) collector is a hybrid component that converts solar energy in both electricity and heat. A glass covered water-based PV–T prototype has been developed in the framework of a partnership between the CETHIL, EDF R&D and Fraunhofer ISE. It offers an unprecedented level of performance in controlled conditions reaching 87% of global efficiency in controlled conditions. In 2012, the project PHOTOTHERM supported by ADEME was launched with the aim of evaluating its performances in real conditions and coupled to a Solar Domestic Hot Water System (SDHWS). In this framework, a full-scale PV–T SDHWS experimental bench was constructed at the Building Envelope & Solar Technology Laboratory (BESTLab) of EDF R&D. A numerical 3D dynamic model of the component has been developed. The aim of this paper is to introduce this high accuracy model and its validation in steady-state and dynamic regimes using monitoring data recovered from BESTLab’s SDHWS facility. The model is fully satisfactory as the discrepancy on the fluid temperature is at the very maximum 2 °C in dynamic state whereas the electrical power generation is slightly under-estimated. This work highlights the necessity to consider temperature levels achieved by each cell depending on the type of heat exchanger and then to consider mismatch effects. It is both important for the dynamical performance of these hybrid collectors but also for maintaining their performances while aging.