Two novel approaches to making electricity from sunlight

ISRAEL is a country with plenty of sunshine, lots of sand and quite a few clever physicists and chemists. Put these together—having first extracted the oxygen from the sand, to leave pure silicon—and you have the ingredients for an innovative solar-power industry. Shining sunlight onto silicon is the most direct way of turning it into electricity (the light knocks electrons free from the silicon atoms), but it is also the most expensive. The scientists are what you need to make the process cheaper. And that is what two small companies based in Jerusalem are trying, in different ways, to do.

The physicists and chemists at GreenSun Energy, led by Renata Reisfeld, think the way is to use less silicon. Traditional solar cells are made of thin sheets of the element covered by glass plates. In GreenSun’s cells, though, only the outer edges of the glass plates are covered by silicon, in the form of thin strips. The trick is to get the light falling on the glass to diffuse sideways to the edges, so that the silicon can turn it into electricity. Dr Reisfeld’s team do this by coating the glass with a combination of dyes and sprinkling it with nanoparticles of a metal whose nature they are not yet willing to disclose. …