A CASE STUDY OF PERFORMANCE OF HYBRID SOLAR COLLECTOR SYSTEM AS COMPARED TO SIDE-BY-SIDE PHOTOVOLTAIC AND WATER-HEATING SYSTEMS

An experimental side-by-side photovoltaic and solar water-heating collector system was set up at one office building ofthe university campus. The electricity output was used to support the exit sign lights via battery storage and changeovercircuit devices for switching between the power company supply and the photovoltaic system on site. The hot watergenerated was consumed in selected pantries of the offices. System performance and difficulties encountered wererecorded for investigation. Numerical models were then developed and successfully validated by the experimentalresults. The computer models were used to examine the year round system performance with the use of typical weatherdata of Hong Kong. Furthermore, hybrid photovoltaic/thermal (PV/T) collector systems were modeled to support thesame functional areas of the building through two different design principles: (i) the emphasis on similarity in collectormaterial usage and energy outputs, and (ii) the emphasis on similarity in overall collector area. It was found that based onthe first design principle the PV/T system does not show much advantage in electricity and thermal energy outputs overthe side-by-side system. However based on the second design principle, the PV/T system is much superior in energyoutput intensity on unit collector area basis. Comparatively, the second design principle is found more important to copewith the increasing demand of zero-carbon buildings, since the renewable energy output has to be maximized within thelimited building space. This article summarizes the findings of this case study by comparing the energy performance ofthe related solar collector systems based on the year round simulation runs. Also reported are the key factors in theservices of the related solar collector systems based on the difficulties encountered in real building application.