Luminiscent Solar Concentrators
Luminescent solar concentrators (LSCs) consist of semitransparent plastic slabs doped with highly emissive chromophores which, upon absorption of the sunlight, emit long-wavelength photons. These photons are guided by total internal reflection to the device edges, where they are converted into electricity by conventional PV cells installed along the slab perimeter. Thanks to their easy integration into active architectural elements, LSCs are considered one of the most promising complement for the achievement of near zero-energy balance buildings in highly- populated urban areas, where rooftop surfaces are insufficient for collecting all the energy required for the building operations.
The technology developed by Glass to Power uses nanoparticles as chromophores, which decouple the processes of absorption and emission of light thanks to an appropriate engineering. This made it possible to build prototypes with good generation efficiency even for areas of hundreds of square centimeters, which can be easily scaled up to the dimensions required for commercial applications. Moreover, LSCs are essentially colorless, which is a key requirement for their application in building-integrated photovoltaics. A complete colorimetric characterization demonstrated that our LSC do not introduce relevant distortion of the transmitted light nor modifications to the indoor-to-outdoor chromatic perception. In conclusion, it is now possible to produce stable, environmentally friendly large-area LSC, with good efficiency ready for BIPV modules.
Glass to Power’s technology allows the development of low-impact photovoltaic windows that can be easily integrated into the architecture of passive buildings, virtually invisible both from the outside and from the interior. Thanks to their homogeneous behavior over the entire sunlight spectrum, our LSCs are essentially colorless, resulting quite similar to sunglasses’ lenses rather than films that are commonly applied to glazed windows to reduce indoor sunlight. The degree of transparency of LSCs, moreover, can be determined at the production stage according to customer’s needs, to obtain the best compromise between absorbed energy and amount of light for indoor lighting. The quality of light transmitted, according to the UNI 10380 certification, is located in group 1A, that is the group with highest quality sources suitable for the lighting of houses, graphic studies, hospitals, etc. In addition, as demonstrated by the Farnsworth-Munsell 100 test, the innovative Glass to Power’s LSCs do not alter color perception when viewing through a photovoltaic window.
Thanks to Glass to Power technology, which allows for exceptional spectral coverage, never achieved in any other type of LSC before, it has been possible to obtain a level of conversion efficiency of light power into electrical power up to 3.2% with a degree of transparency in the visible spectrum of around 80% (that is, only 20% of the light is used for power generation while the remaining 80% goes through the panel to illuminate the indoor environment). The optical conversion efficiency of the blue/ultraviolet fraction of the solar spectrum reaches record values of over 10%. In addition, “ray-tracing” simulations based on experimental data obtained from our prototypes show that these performance is also conserved for large dimensions, paving the way for photovoltaic windows with efficiency levels exceeding 5%.
Glass to Power uses only intrinsically very stable and durable materials for the production of its LSCs. Plastic panels are made of high quality plexiglass already commonly used in building applications. Nanoparticles are made entirely of inorganic materials such as silicon, which are intrinsically stable to solar irradiation without any risk of degradation, guaranteeing continuity and durability of electricity generation.
Glass to Power respects the environment by using for its LSCs only high quality easily recyclable plexiglass and silicon nanoparticles or other inert semiconductors without heavy metals. The use of a surface, per kW of power produced, of traditional photovoltaic cells far below that of a common integrated photovoltaic system reduces the end-of-life disposal problems of these devices.