[DManA]

I don’t get the advangage. Say you have a lense 20/20 cm. You concentrate the energy falling onto 400 sq cm into a smaller area. But then you throw away a lot of that energy with the “clever” cooling technology so, what’s the point?

[taxcontrol]

It is not a physics efficiency, it is a cost efficiency. By that, I mean that instead of either building one big PV cell to handle a 20x20 cm2 area, or by having to have 400 PV cells, you can now have a SINGLE cell. The most expensive part of converting light to electricity is the PV cell itself. IBM's trick is be able to concentrate so you don't need as many PV cells.

Yes some energy is lost in the cooling but that percent is much smaller than the cost efficiency gained by reducing the number of cells for the same area from 400 to 1.

[DManA]

Why not just use a smaller lense so the temperature doesn’t rise to the point that you have to cool it?