This light-guide construction serves as a light concentrator that concentrates some of the light energy that is received on the surface of the window at smaller edge-installed solar cells. The
solar cells can thus operate at higher energy densities, reducing cost and increasing the effectiveness of the system. Since incident light is split simply by the diffusive particles inside the nanocomposite light-guide plate, the light that directly passes through the structure and provides the view is merely of lower intensity than the incident light. The color distortion of the view is therefore minimized. To a person behind the window, the view is simply darker, as if observed through a pair of sunglasses. Additionally the transparency of the window can be controlled by controlling the characteristics of the embedding diffusive nanoparticles. Fig. 7
schematically compares the efficiency and transmittance of various solar power windows. Typical thin-film solar cells have some current-collecting grids, which inevitably block the view
through the window. The layered structure (Glass/PC/Glass) of a diffusive solar cell window improves its mechanical properties. Fig. 8 presents a typical diffusive solar cell window for architectural applications. Such a window module is ideal for houses and buildings, and even for vehicles. Each window may generate only a small amount of electricity, but combined, as in a large business/ office building, the collected solar power can significantly affect the
energy budget of the entire building. Furthermore, such building window modules can also be equipped with a charging battery system to store captured solar energy for use in traffic signs or advertisement boards, as shown in Fig. 9. These illuminating windows would be off of the grid. The outdoor performance of the transparent solar cell windows that were developed herein has been monitored for more than nine months. No evidence of degradation of the diffusive solar cell window has been found.