Numerical and experimental study of semi-transparent photovoltaics integrated into commercial building facades

Semi-transparent photovoltaics (STPV) have a large potential for integration in fenestration systems, adding the option of solar electricity production while still allowing for satisfaction of daylight needs. In office buildings, where the trends in architecture already include large glazed facades, and lighting loads constitute a significant portion of the overall energy consumption and, the integration of this technology is intuitive. This thesis studies the potential of using either spaced opaque PV (photovoltaics) or thin-film PV and examines the impact of changing the PV area ratio (ratio of photovoltaics coverage to fenestration area) on the facade. It includes a verification of the workplane illuminance and PV output simulation models through comparison with measured data from an experimental office with a specially built full-scale prototype of a window with spaced solar cells. The thesis addresses the issue of optimizing the PV area ratio for a simplified model based on a typical office in Montreal with an evenly divided south facing 3-section facade, which is an optimized facade concept that allows for view, adequate daylight and reduced heating/cooling loads. Several parametric variations are taken into consideration including facade orientation, site location, PV efficiency, lighting control strategies and shading device transmittance. The annual simulation results show that a facade with integrated STPV has the potential to improve the overall energy performance when compared with opaque PV due to the significant daylighting benefits even at low transparency ratios. At approximately 90% PV area ratio in the upper section of the facade, the daylighting needs of the room are met; at higher PV area ratios the lighting loads increase rapidly and at lower ratios, the additional natural lighting does not enhance the performance further.

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