Lighting performance of multifunctional PV windows

To show how much photovoltaic windows improve daylight distribution of a deep-plan office by both reducing glare and powering supplementary lighting, a numerical experiment based on radiosity and raytracing methods was conducted. The chosen model geometry was a laterally lit, deep-plan office room. A desk 7.50 m away from the window provides a work plane for illuminance analysis. Ten scenarios were considered: A) single colourless, transparent single-glazed window; B) PV window as an array of multicrystalline separate silicon cells, mounted on a transparent glazing; C) transparent thin-film PV window. Respectively, A1, B1 and C1 are under direct solar radiation; B2 and C2 with net-zero electric lighting based on two luminaires; and B3 and C3 based on a single luminaire. Static analysis yields illuminance distribution on the horizontal plane at 0.75 m above floor along a central axis. Advantages were observed on scenarios B2, C2, B3 and C3, as shown by realistic images. Dynamic analysis was conducted for the scenarios A1*, B1*, C1*, B2* and C2*. Whole-year calculation of work plane illuminance, continuous Daylight Autonomy (cDA) and Daylight Glare Index (DGI) results show the superiority thin-film PV with supplementary lighting, (scenario C2*).