Typical photovoltaic concentrators are complex, follow the Sun and their optical focusing systems are very expensive. They focus the sunlight onto a smaller area of a PV cell, usually turning the entire concentrator render more efficient results than if posting the cell directly under the Sun.
Tapas Mallick, at Heriot-Watt University in Edinburgh, UK, is developing a grid of cheap light concentrators that can be mounted on walls, rooftops or between the panes of double-gazed windows. Every concentrator he builds has the shape of a funnel, with the light entering through an egg-shaped opening that can collect the sunlight from every angle, needing no expensive Sun tracking device.
At the other end, a PV device traps the incoming light and reflects it internally until every last photon is absorbed into the cell. The phenomenon is called “total internal reflection”.
Mallick has been experimenting with various polymers, of which the best seems to be plexiglas (or perspex). Plexiglas has a higher refractive index than air, making the total internal reflection happen. He is also planning to reduce the cost of such a device by 40 percent, with an electrical efficiency of 20 percent.
Mallick calculates that his concentrator PV cells would produce 200 watts per square meter, making his technology more efficient than any previous attempts that used Graetzel cells which only have a 5 to 6 percent efficiency.
Also, he is planning a system that would recover part of the energy lost through heat. Others have also tried this, and when I’m saying this I remember Dow Chemicals with their PV shingles that exploit both light and heat coming from the Sun.