Stratospheric solar array

This is something that has been brewing in my mind for a while that seems to have enormous potential.

The basic concept is to have a vast constellation of hydrogen blimps floating in the stratosphere collecting the sun's energy.

Having them in the stratosphere has many advantages:

• In permanent sunshine
• Above most of the weather
• Out of the way of air traffic and wildlife
• The hours of sunshine are slightly increases due to the altitude
• Less attenuation of sunlight due to being above 2/3 of the atmosphere
• Do not take up any land

If the array is far out in the ocean then there is no shadow being cast where people live and no-one will be able to see it. Even where there is shadow it will be no different to shadow from cloud except that it will be more fragmented due to the spacing of the blimps.

Photovoltaic cells are still very expensive, especially ones with high efficiencies (30%). It may be better to use parabolic reflectors aiming the light onto a thermal recievers. These have been developed at Sandia National Laboratories in the US, the EU's SolAir project and by companies such as Stirling