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A novel semi-transparent building integrated photovoltaic (BIPV) laminate was developed and introduced in this paper. It was produced by cutting standard mono-crystalline silicon solar cells into small strips and then making electrical connections between each strip before laminating the cells between two layers of glass. The overall energy performance and energy saving potential of the BIPV insulated glass unit (IGU) under real world conditions were identified through a side by side comparative study. Compared to the reference IGU, the BIPV IGU had lower solar heat gain coefficient (SHGC) but much higher U-factor. The average HVAC electricity saving of the BIPV IGU was about 10% relative to the reference IGU. Daylighting measurement and analysis were carried out to evaluate the trade-offs associated with the BIPV IGU between daylight, glare, and lighting energy use. The results indicated that the BIPV IGU is better than the reference IGU in reducing discomfort glare. However, if the most conservative viewpoint near the window is used for the assessment, a lower transmittance BIPV IGU is required to bring the overall discomfort levels below the perceptible level. Lastly, the net energy saving potential associated with the novel BIPV IGU was identified based on the power, thermal and daylighting performance. On average, the BIPV IGU saved 16.8% of the total electricity use of the room. Further studies and improvement on the energy conversion efficiency of solar cells, the optimal transmittance as well as the thermal properties would make this technology more energy-efficient and affordable.

A comprehensive simulation model has been developed in this paper to simulate the overall energy performance of an amorphous silicon (a-Si) based photovoltaic double-skin facade (PV-DSF). The methodology and the model simulation procedure are presented in detail. To simulate the overall energy performance, the airflow network model, daylighting model, and the Sandia Array Performance Model in the EnergyPlus software were adopted to simultaneously simulate the thermal, daylighting, and dynamic power output performances of the PV-DSF. The interaction effects between thermal, daylighting, and the power output performances of the PV-DSF were reasonably well modeled by coupling the energy generation, heat-transfer, and optical models. Simulation results were compared with measured data from an outdoor test facility in Hong Kong in which the PV-DSF performance was measured. The model validation work showed that most of the simulated results agreed very well with the measured data except for a modest overestimation of heat gains in the afternoons. In particular, the root-mean-square error between the simulated monthly AC energy output and the measured quantity was only 2.47%. The validation results indicate that the simulation model developed in this study can accurately simulate the overall energy performance of the semi-transparent PV-DSF. This model can, therefore, be an effective tool for carrying out optimum design and sensitivity analyses for PV-DSFs in different climate zones. The methodology developed in this paper also provides a useful reference and starting point for the modeling of other kinds of semi-transparent thin-film PV windows or facades. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]