Even if solar cells like this are eventually built and put to work, they will still contribute to global warming. That is because they convert only a small fraction of the light that hits them, and absorb most of the rest, converting it to heat that spills into the environment. Sustainable solar energy may therefore require cells that reflect the light they cannot use.
Consider a rock, sitting in the sunshine. Photons hit it, yes. If it\’s dark rock, most are absorbed, not reflected. That\’s why rocks get hot on a sunny day, because the photons are turned into heat.
So now we have a special rock, a solar cell. Some of those photons that would have been absorbed, become heat, are now going off and making electricity. So, err, we\’ve got less heat than if we just had rocks instead.
It seems that the New Scientist is thus trying to tell us that it\’s rocks that are responsible for global warming. Presumably we just paint the whole place white then?