An experimental study of façade-integrated photovoltaic/water-heating system

The worldwide fast development of building-integrated solar technology has prompted the design alternatives of fixing the solar panels on the building façades. How to make full use of an integrative system to achieve the best energy performance can be an important area in the technology promotion. Hybrid solar system applying in buildings has the advantage of increasing the energy output per unit installed collector area. This paper describes an experimental study of a centralized photovoltaic and hot water collector wall system that can serve as a water pre-heating system. Collectors are mounted at vertical facades. Different operating modes were performed with measurements in different seasons. Natural water circulation was found more preferable than forced circulation in this hybrid solar collector system. The thermal efficiency was found 38.9% at zero reduced temperature, and the corresponding electricity conversion efficiency was 8.56%, during the late summer of Hong Kong. With the PVT wall, the space thermal loads can be much reduced both in summer and winter, leading to substantial energy savings. Suggestions were given on how to further improve the system performance.