The solar industry is making great strides in bringing down costs. As manufacturing capacity has ramped up in the past few years, scale has produced efficiency gains, bringing down prices for consumers.

However, there is one critical problem with solar – the sun is not always shining. This means that the capacity factor – the amount of time that the solar panel is producing energy relative to the total theoretical amount according to its nameplate capacity – only reaches about 20%. While energy storage could smooth out fluctuations, the variability remains a problem.

An interesting article in Strategic Studies Quarterly by Peter Garretson, Lt.Col., USAF, explores one possible route around the pesky problem of the sun not shining all the time – space-based solar power (SBSP).  Under this approach, huge arrays of solar panels would be put into space, and “beam” the energy down to earth. The panels would be bombarded by solar energy without interruption (there is no nighttime in space), and the solar radiation would be 36% stronger to boot. That energy could then provide solar energy 24 hours a day on Earth.

The solar “satellites” could also serve markets that span vast distances. For instance, Garretson says, “a single satellite south of Baja California could service markets across most of North and South America; a satellite over the Indian Ocean could service markets as far apart as Africa and Indonesia, and from Diego Garcia to as far north as Russia.” This is SBSP’s ‘killer app’: it can provide on-demand energy to anywhere in the world. There are obvious military applications for this – imagine forward-deployed bases that did not require resupply routes because they were powered by energy beamed down from space.

Despite the promise, at first blush SBSP would appear to be an unimaginable engineering feat. Indeed it sounds like science-fiction. A “multi-gigawatt” solar system would need to be several kilometers in surface area, requiring hundreds of space launches to get the material into space. To put that into context, the U.S. launched only 18 rockets into space last year.

Garretson acknowledges the criticism, pointing to the fact that critics say solar has yet to become competitive on Earth, so how could installing thousands of solar panels in space come remotely close to being cost-effective?

Garretson asserts that SBSP could also meet several strategic objectives already laid out by the United States. For example, building SBSP would necessarily mean the U.S. would have to make significant leaps in space-related technologies. Also, building a solar industry in space would also provide the U.S. with the opportunity to strengthen stability in space, provide commercial opportunities, and train a generation of scientists and engineers.

Ultimately, whether or not we pursue space-based solar power comes down to the criticism that Garretson believes is most convincing. That is the question of opportunity costs. Using scarce resources on SBSP means that less is available for other important areas, like education, national defense, or healthcare. More directly, SBSP will be competing with other energy technologies, and since SBSP’s time horizon is decades away, it will be difficult to justify large-scale investments.

ASP has explored SBSP in the past. Last November, ASP hosted John Mankins, President of Artemis Innovation Management Solutions LLC, who gave a presentation on the importance of SBSP. As private companies begin lining up to take advantage of business opportunities in space exploration, SBSP could be more realistic than many believe. As ASP Senior Fellow Andrew Holland noted in a blog post last November, it is especially important for the future of SBSP that private companies get involved because cash-strapped governments will probably not foot the bill. If there is money to be made, SBSP may be best left to the private sector.

To read more about space-based solar power, check out ASP’s work on it by clicking here.

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