Building Integrated Photovoltaic Thermal Systems PDF Download

Building-Integrated Photovoltaic/Thermal Systems (BIPV/T) systems are photovoltaic installations incorporated as the exterior layer of the building envelope with the additional function of recovering thermal energy, which can then be used for space heating, domestic water heating and possibly for cooling. Some advantages of a BIPV/T system over an autonomous PV array include lower installation costs due to the replacement of cladding material, elimination of extra support structures and reduced electrical transmission losses. In addition, recovering the heat from the photovoltaic panels cools them and thus improves their electrical efficiency. Due to the novelty of BIPV/T systems, there is a need for the measurement of convective heat transfer coefficients and development of correlations for their prediction. The development of an integrated energy model, including correlations for the prediction of convective heat transfer coefficients in BIPV/T systems was one of the main objectives of this thesis. Accurate measurements of convective heat transfer coefficients have been carried out for two open loop BIPV/T configurations: smooth and ribbed. The BIPV/T systems were tested at 30°-45° tilt angles and had a length/hydraulic diameter ratio of 38 which is representative of roof applications. It was found that for the BIPV/T ribbed case, the calculated Nusselt numbers are on average 2.6 times higher than the Nusselt numbers predicted by the Dittus-Boelter correlation. Pressure drop measurements were performed for the two configurations and the results are presented in terms of the Darcy friction factors and compared to the Blasius equation. For both cases, the friction factors are higher compared to the ones predicted by the Blasius equation. Previous existing electrical photovoltaic models have been used to couple their features to the lumped parameter thermal network modelling approach used in this thesis. Two thermal network models, steady state and transient, have been developed in this work and validated against experimental data. The steady state model is useful for a quick evaluation of the thermal/electrical performance, while the transient model gives a more accurate representation of the system by considering the thermal storage capacity of the materials. Finally, conclusions and general recommendations and guidelines for the design and construction of BIVP/T systems are provided.