Could space-based solar finally be in reach?

Solar panels on a satellite. Credit: Artsiom P via Shutterstock

Beaming solar energy down from space sounds like science fiction — Isaac Asimov wrote of it in a 1940 short story — but in fact, it’s a very real solution to our ever-growing need for clean energy. 

In theory, it works like this: solar panels positioned on satellites receive energy from the sun, and then transmit this energy to Earth via either microwaves or lasers. Receivers on earth then take this energy and store it in battery plants, where it can be used as a source of clean energy for homes, businesses and industry. 

The benefits of such a process are significant; unlike solar panels on Earth, space-based solar farms could generate energy 24 hours a day, and as a result could generate 40 times as much energy as Earth-based solar power. 

Scientists have been developing space-based solar technology for half a century, and in the past five years there has been increasing discussion of tests for smaller space based solar farms. Excitingly, a few recent technological developments in the field might have the answers to some of the problems that have held back this technology for decades, including prohibitive costs and the logistical challenges of building power generation facilities so far from Earth.

One of the major challenges surrounding space-based solar power is the rate at which solar panels degrade. The intense radiation these panels are exposed to can cause them to lose up to 40% of their efficiency over a ten-year period, which presents a significant challenge for establishing long-term space-based solar power projects. 

On 28 March this year, Arizona-based firm Solestial made an announcement that could solve this problem. Solestial has developed ultrathin silicon solar cells that are capable of annealing under sunlight at 90°C, effectively enabling them to repair the damage done by solar radiation.

Independent tests carried out by the French Alternative Energies and Atomic Energy Commission (CEA) found that when exposed to the equivalent radiation of ten years in low Earth orbit, Solestial’s solar cells lost only 4% of their efficiency, a significant reduction from the current industry standard.

In a press release, Stanislau Herasimenka, co-founder and CEO of Solestial, described this kind of low-temperature curing as a “critical capability” for silicon-based solar products in space. He added: “We look forward to further testing with the CEA over the coming months to validate internal annealing results at even lower temperatures. 

“We’re excited to show the space industry the myriad benefits of Solestial’s ultrathin silicon solar cells and blankets.” 

If the next generation of solar panels have much longer lifespans, repair and replacement costs could well fall to a point that tips the technology into being economically viable, an exciting prospect for the future of the space-based solar industry.

China is one of the leading players in the race for commercial space-based solar power, thanks to its ambitious plans to launch a space solar power plant programme by 2028. This January, Duan Baoyan, professor of mechatronics at Xidian University and a lead scientist in the Chinese space solar power plant programme, revealed details of an innovative new cooling system in a paper published in Scientia Sinica Technologica. 

This system has the potential to drastically improve the overheating problems plaguing the project up to now, thanks to an interesting source of design inspiration: butterfly wings.

The newly designed OMEGA-2.0 generator features multiple large, yet lightweight, structures that mimic the shape and anatomy of butterfly wings, which allows the generator to dissipate heat more effectively. These ‘wings’ feature tiny vein-like structures filled with flowing fluids, which facilitate heat exchange. 

According to the engineer’s calculations, this structure could almost halve the temperature of the generator, when compared to the previous design. 

Other design changes to the OMEGA-2.0 design could also improve the success of the experiment, including changes to the microwave antennas and a new ultra-high-powered electric propulsion system, currently under development in Shanghai.

Arguably the largest barrier to a future of commercial space-based solar farms is the vast financial cost of the technology at present. Put simply, space-based solar is currently prohibitively expensive for commercial purposes, but this may not be the case for much longer. 

The increasing popularity of reusable rockets, pioneered in no small part by SpaceX and the rise of private space launch providers, has triggered a steep decline in the price of launching material into space. The falling cost is opening up the possibility of research into space-based solar power for smaller teams and academic institutions; Caltech recently launched three solar experiments into space aboard a SpaceX rocket. 

Last year, the European Space Agency (ESA) commissioned two cost-benefit analyses of space-based solar power, one from Germany’s Roland Berger, and one from Frazer-Nash in the UK.

Both studies concluded that space-based solar power could provide competitively-priced electricity to European homes and businesses by 2040, and also noted that it would provide “substantial environmental, economic and strategic benefits for Europe, including energy security” when deployed at scale. 

Given the increasing economic viability for space-based solar, it’s unsurprising that funding is being poured into the sector. In May 2022, NASA announced a study to re-examine the viability of space-based solar power, the European Research Council recently awarded Warwick University a $2.8m research grant for a five-year study, and the ESA’s Solaris project was approved in November 2022.

While all these developments are promising, we are likely a decade or more away from space-based solar becoming a part of our sustainable energy mix. 

There are still many technological hurdles to overcome, a point which the ESA made clear when publishing the results of their cost-benefit analyses: “A lot of challenging technology developments are still needed to mature the feasibility of collecting gigawatts of power in space, per satellite, and delivering it efficiently and safely to users on Earth.” 

Even the most optimistic forecasts place this technology around a quarter-century away, and if the nuclear fusion industry has demonstrated anything, it’s that developing new and innovative technologies rarely runs to a promised timeline.

There is cause for optimism though. If nothing else, the sheer mass of funding being pushed into research and development for space based solar power is a sign of the global commitment to bringing this technology to life, and that funding brings with it the hope of a quickened pace for implementation. 

The strong use-case for space-based solar power makes a future where it forms part of the world’s energy mix one worth striving for, and these new developments inching the power industry closer to that future are worth celebrating.