We’ve reported in the past on plans for putting solar panels on the moon and space-based solar power stations transmitting electricity back to Earth. A little closer to home, but still high above our planet’s surface, is a concept from StratoSolar – a utility scale PV system tethered and floating at an altitude of 20 kilometers.
The California-based company wants to exploit the benefits Earth’s stratosphere has to offer PV based electricity generation. Our stratosphere is a comparatively calm area isolated from the turbulent troposphere below. It experiences no cloud or precipitation and temperatures are low, improving solar cell efficiency. Light from the sun at a 20km altitude is strong and uninterrupted from dawn to dusk.
At that height, the company says solar panels are exposed to 1.5 to 3.5X the solar energy compared to ground-based PV modules.
The StratoSolar system is comprised of a solar panel array attached to a buoyant platform permanently positioned in the stratosphere. Electricity generated by the solar panels would be transmitted via a tether/high voltage (HV) cable to the ground where it would connect to the mains grid. The company says utility scale systems of 10 MW to 1 GW capacity could be constructed in modular increments.
Solar panels for this application can be made from cheap, lightweight materials already available. Where extra cost is incurred is in the tether/high voltage cable, winch, gas bags and the hydrogen needed to keep the array aloft. However, Stratosolar says the capital cost of their sky-based solar farm is equivalent to or cheaper than a land based facility and will generate far more electricity at a cost of around US $0.10/kWh – without any form of subsidy.
As the system doesn’t require huge chunks of land, it will also save on an expensive, important resource; plus allow for great flexibility in location.
Ice, lightning, hydrogen fires, extreme weather events, stations falling from the sky, maintenance and all sorts of other questions spring to mind about the concept’s viability, questions addressed in StratoSolar’s FAQ.