Energy savings of office buildings by the use of semi-transparent solar cells for windows

The study investigated a PV window that consists of a double glazed window with semi-transparent solar cells. The window provides natural light transmission as well as electricity production. The effect of the PV window on energy consumption of office buildings was analyzed in terms of heating and cooling loads, daylighting, and electricity production. The purposes of the study were to find the optimum solar cell transmittance and window to wall ratio (WWR), and to estimate energy savings of the building. A standard floor of an office building was modeled to run computer simulation, and annual energy simulation was performed with EnergyPlus. The results showed that the solar cell transmittance of 40% and WWR of 50% achieved the minimum electricity consumption in the building when artificial lighting was controlled with daylighting. The optimum solar cell transmittance for PV windows in different orientation was also presented. By using the optimum PV window, the electricity consumption was reduced by 55% compared to the single glazed window with WWR of 30% and no lighting control.