[thedoc]

Solar cells waste much of the energy from the Sun because they cannot use it efficiently, but Per-Anders Hansen from the University of Oslo may have a way to improve the situation...
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[Atomic-S]

Interesting. I understand also that the solar cells used on some space probes are much more efficient than the kind usually found on Earth, and I believe the reason is that they have three layers, each responding to a different wavelength band. I understand they also are much more expensive. Also, not long ago there was a report of an enhanced solar collector that is a hybrid design: part photovoltaic and part thermal. It uses a curved mirror to concentrate sunlight on a tube that carries a fluid, but the tube is also covered by photovoltaic cells. And then there was another report about an improved system that relies upon a curved mirror collecting sunlight upon an advanced photovoltaic collector of unknown design, which is actually rather expensive, but because it is small compared to the total collecting area, the system actually ends up being cheaper per watt than a standard solar panel. This particular device, as I recall, was invented by Roger Angel the optics expert of the University of Arizona.

[CliffordK]

Interesting approach.

Can one use infrared to generate the energy, as it is easy to make IR emitters.  Perhaps carbon nanotubes which would absorb broad spectrum light, and re-emit IR, although it may not be in a single wavelength.

One problem is that I assume emissions are omnidirectional.  So, if one thinks like a cube, then at least 1/6 of the light would be re-emitted back towards the source, and thus would be lost.  On a plane, the loss could be much higher.

Adding more places for loss of energy also seems dangerous, so while the absorption of red might be twice as efficient for energy input as violet, that added efficiency could be quickly lost.  Nonetheless, it is worth trying.

As far as the triple junction cells, they are most efficient on Earth with concentrated light which means that they must have a solar tracking system.  It is likely that one of the differences between terrestrial solar panels and space solar panels is the broad frequencies of light that is absorbed by our atmosphere.

It is quite possible that the Per-Anders Hansen system would also benefit from concentrated light.