Toward an Optimum Design of an Amorphous Silicon Photovoltaic/Thermal System:Simulation and Experiments

Amorphous silicon photovoltaic/thermal(a-Si-PV/T)technology is promising due to the low power temperature coefficient,thin-film property,thermal annealing effect of the solar cells,and high conversion efficiency in summer.The design of a-Si-PV/T system is influenced by a number of thermodynamic,structural,and external parameters.Parametric analysis is useful for a good design of the system.A dynamic distributed parameter model is built and verified in this paper.Outdoor tests are carried out.The impacts of operating temperature,mass flow rate,cover ratio of solar cells,heat transfer area,and frame shadow ratio on its performance are theoretically and experimentally investigated.The results indicate that seven or eight copper tubes are suitable to achieve a high overall efficiency of the a-Si-PV/T system.The frame and tilt angle shall avoid a shadow ratio of more than 8.3%during operation.The difference between power outputs at operating temperatures of 35℃and55℃in the first month is about 0.21%while it drops to less than 0.1%in the twelfth month.Compared with conventional PVT systems,the a-Si-PV/T system benefits from a higher design temperature with a minor efficiency decrement.