Buildings in bit cities often lack the space for roof-mounted solar PV but have large windows that catch the light. Researchers from New Mexico have discovered that by adding a film of quantum dots on the glass, a window-based solar PV system could be possible - at an affordable cost.

The team from Los Alamos National Laboratory have been researching ways to capture the sun's rays through plain glass windows and harness it for clean power. Previous experiments have tried to use organic dyes to concentrate light beams, but the new use of nano technology has resulted in a system that could last for over a decade. The current conversion efficiency is just 1.9pc, and the scientists are now working to find a way to increase this to 6pc so that the system can be commercially viable.

What is particularly interesting is how simple it is to create the glass. Machinery pours a slurry mix of PVC polymer and quantum dots on to a glass surface, where it is spread by a blade to make a thin layer. This newly created thin layer builds on previous attempts and ensures that the lights rays don't scatter too much and instead propagate for much longer.

This is essential for creating a system that is cost-effective and which can work over large areas. Interestingly too, early studies suggest that the special solar coating could even be scraped back off glass and then be re-used.

In the meantime, the work continues on reaching the 6pc break-even point for the solar power conversion, with the researchers adjusting the quantum dot concentrations used and their properties for absorption. It is certainly a fascinating and potentially very exciting field of development in the quest to bring affordable green energy to the world.