Experimental And Theoretical Study On Photovoltaic Roofs

To improve building energy efficiency and reduce fossil fuel dependence, it is important to combine solar energy technology with energy-efficient construction techniques. BIPV (Building Intergraded Photovoltaic) can play a decisive role in transforming building from an energy consumer to an energy producer.To predict accurately the BIPV system performance, new models was developed for three different building integrations, which are PV roofs with ventilated air gap, non-ventilated, and the close mount, respectively. PV module was regarded as five layers: tempered glass cover, upper EVA, solar cell, lower EVA, and TPT. Heat transfer between five layers and between PV module and ambient environment are taken into account. The new models combined the PV Sandia electrical performance model and Radiant Time Series model for building heating and cooing load to calculate the PV power output and building thermal load through PV roof.Three PV roofs and conventional roof were set up in Tianjin, China and their thermal performances are analyzed. The experimental values and theoretical values are compared and the results show that the model can predict accurately thermal performance of PV roofs. Then based on the model, the PV power and building thermal performance were investigated after installing different PV integrations. Lastly, the appropriate method for PV roof was evaluated in five building zones (severe cold zone, cold zone, hot summer and cold winter zone, hot summer and warm winter zone, temperate zone).