By Ben Coxworth

Imagine if all the windows of a building, and perhaps even all its exterior walls, could be put to use as solar collectors. Soon, you may not have to imagine it, as the Norweigan solar power company EnSol has patented a thin film solar cell technology designed to be sprayed on to just such surfaces. Unlike traditional silicon-based solar cells, the film is composed of metal nanoparticles embedded in a transparent composite matrix, and operates on a different principle. EnSol is now developing the product with help from the University of Leicester’s Department of Physics and Astronomy.

"One of the key advantages is that it is a transparent thin film that can be coated onto window glass so that windows in buildings can also become power generators,” said Chris Binns, Professor of Nanotechnology at Leicester. “Obviously some light has to be absorbed in order to generate power but the windows would just have a slight tinting (though a transmission of only 8-10% is common place for windows in the ‘sun belt’ areas of the world). Conversely the structural material of the building can also be coated with a higher degree of absorption. This could be side panels of the building itself, or even in the form of ‘clip-together’ solar roof tiles.”

For the time being, the research partners are developing prototype squares of the material, measuring 16 square centimeters each. The researchers say that, due to nanotech research that has already been performed at Leicester, the institution is uniquely suited for production of the film. Ultimately, EnSol hopes to achieve a cell efficiency of at least 20 percent, and have its product ready for the commercial market by 2016.

This development is reminiscent of Sphelar cells – solidified silicon drop-based solar cells recently developed by Kyosemi Corporation. Although the technology is different, they are also intended to be used in solar panels that double as windows.