Energy impact of transparent photovoltaic windows

Building-integrated photovoltaics (BIPV) are a leading renewable energy solution for addressing building energy consumption. Transparent photovoltaic (TPV) technology significantly expands the design potential for BIPV by increasing the available solar-absorbing surface area. This technology meets the market demand for transparent facades and enables a more seamless architectural integration. This study first reviews semi-transparent and transparent PV technologies and assesses their potential impacts on building energy performance. It then employs the whole-building energy simulation program EnergyPlus to model a U.S. Department of Energy (DOE) benchmark mid-rise commercial office building in Denver, Colorado. The simulation evaluates the viability of commercially available TPV products and identifies the key properties that high-performance photovoltaic windows must possess. The research indicates that TPV technology has not yet advanced sufficiently to independently offset the total energy consumption of a mid-rise commercial building, nor even the interior equipment loads alone. Consequently, TPV windows are best viewed as a supplementary method of energy generation for the foreseeable future. This study further demonstrates that the window performance properties of commercially available TPV modules – specifically U-value, Solar Heat Gain Coefficient (SHGC), and visible transmittance (VT) – are vital considerations for their effective application. Among these, the U-value exerts a significant influence on whole-building energy consumption. A 75 % reduction in the U-value of south-facing windows can yield a 1.83 % reduction in the net energy use of a building with a 30 % Window-to-Wall Ratio (WWR). Although less impactful on direct energy savings than U-value, high visible transmittance remains a critically important property for occupant comfort and effective daylighting, as it directly affects both solar cell performance and the quality of light in space. An optimal visible transmittance is identified at 44 % or greater for the cases studied.