Operation strategy optimization and heat transfer characteristic analysis of photovoltaic/thermal module series connected with flat plate solar collector: System experimental study

Flat plate solar collector (FPSC) produces only thermal energy without electricity, whereas the photovoltaic thermal (PV/T) module produces electricity and low-temperature thermal energy. This paper presents a low-cost method to strengthen the functional uniqueness of individual PV/T and FPSC components through connecting a PV/T module in series with the other component. Under various water volume conditions, an experimental test on high mass flow rate was carried out. Results showed that the FPSC produced a better heating contribution and that reverse heat transfer of the PV/T module might be reduced by changing the operation strategy. The water volume is a crucial factor that influences the system's available heating time, a system that operates in the optimal water volume range will produce greater energy savings. Furthermore, the maximum values of the thermal, electrical, exergy, and primary energy-saving efficiency were 51.91 %, 13.52 %, 19.13 %, and 87.20 %, respectively. The optimal water volume distribution range of the system is 160-180 L. With an average annual decrease of 2.96 t in CO2 emissions, the system provides a 4.28-year payback period and saves 5285.71 USD in electricity costs throughout its life cycle. The novel system performs extremely well in terms of energy and cost efficiency.