HoloSunTM is a unique and patented glass-coating film which, when integrated into window design, maximizes electricity production from solar PV cells by concentrating sunlight onto the cells. This passive tracking makes it an ideal candidate to leverage the abundant yet stationary surface of a building for electricity generation. HoloSun™ is adhered to the interior surface of double-paned glass, where it is protected from outside elements and indoor wear-and-tear. As the sun's rays strike the HoloSun™ film, a portion of the solar energy is diverted. Rather than passing through the glass, the diverted solar energy is instead channeled through the pane of glass itself (a process known as Total Internal Reflection). Using the glass as a light-guide, the diverted light rays are delivered to PV cells strategically placed in low-value or unobtrusive locations in the glass. In this way, a large portion of glass can be used to collect and deliver solar energy to a relatively small amount of PV material.

The electricity that a PV cell generates is dependent on the wavelength of light that strikes its surface. Wavelengths larger than the solar-cell bandwidth of the PV cell are not able to generate electricity but instead generate heat, which decreases the efficiency of the system. To address this problem, HoloSun™ can be tuned to attract and focus specific spectrums of sunlight onto the PV cells. Focusing the ideal frequencies on cells to convert the maximum possible light into electricity while heat-generating frequencies are directed away from the cells can significantly mitigate the degrading effects of increased temperature.

PV balcony on a residential building in Ekoviikki in Finland. Courtesy: Solpros, Finland