The integration of semi-transparent photovoltaics on greenhouse roof for energy and plant production

The aim of this study was to investigate the effect of semi-transparent building integrated photovoltaics (BIPV) mounted on top of a greenhouse, on the growth of tomatoes and microclimate conditions as well as to estimate the generated energy and the payback period of this system. Three modules were settled at 20% of the greenhouse roof area at a tilt angle of 30° facing south at a distance of 0.08 m between the plastic cover and the BIPV. Each module has a peak power of 170 Wp and efficiency of 8.25%. Results revealed that the annual generated electric energy of the BIPV was 637 kWh. Furthermore, there were no significant differences (P < .05) in the growth of tomatoes between shaded greenhouse by the BIPV and the un-shaded greenhouse. The reduction of solar radiation under the BIPV was 35%-40% more than the Polyethylene covers on clear days. The BIPV shading decreases the air temperature by (1 °C-3 °C) on clear days and has no effect on relative humidity. The payback period was found to be 9 years. Moreover, this system can provide most of the annual energy demands for the greenhouse environmental control systems.