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European Space Agency explores concepts for space-based solar farms

by Liam Turner
An ESA concept for how an orbital solar farm would transmit solar energy collected in space to Earth

The European Space Agency (ESA) is exploring the use of solar farms based in space, following the signing of contracts for two parallel concept studies for commercial-scale plants.

The ESA says the development marks a “crucial step” in its new SOLARIS initiative and represents a maturing of the feasibility of gathering solar energy from space for terrestrial clean energy needs.

Due to be completed before the end of 2023, the concepts will serve as a reference for the overall SOLARIS effort, guiding the scope of specific R&D activities.  

In theory, space-based solar power works by gathering power above the Earth’s atmosphere – where it is available continuously and in plentiful supply and unaffected by local weather or darkness – then sending it down wirelessly to Earth.

The ESA says the concept complements rather than competes with terrestrial renewables, because space-based solar power can make power available reliably on an ongoing 24/7 basis.

It says this system would bring about stability to the electricity grid as the share of intermittent renewables continues to increase, reducing dependence on large-scale storage solutions.


SOLARIS was approved at the ESA Council at ministerial level last November as part of Element 1 of the existing General Support Technology Programme.

Working with European industry, its goal over the next two and a half years is to undertake studies and technology developments to assess the benefits, implementation options, commercial opportunities, and risks of space-based solar power as a contributor to terrestrial energy net-zero decarbonisation for Europe.

It is hoped that results from SOLARIS will allow Europe to make an informed decision by the end of 2025 on proceeding with a full development programme for commercial-scale space-based solar power.

A subscale in-orbit demonstrator to beam power from space to Earth would then follow.

‘Blank sheet’

Sanjay Vijendran, ESA’s lead for SOLARIS, said: “These contracts are for the first European concept studies of Space-Based Solar Power for more than 20 years, so today marks an important step.

“We are really starting from a blank sheet of paper to get an up-to-date design for what working solar power satellites could look like, sourcing promising ideas from everywhere we can, and leveraging the latest advancements in space and terrestrial technologies.”

He added: “The studies will look at as wide a range of options as possible, including investigating all the different ways to move the energy, safely and efficiently, down to Earth: radio frequency transmission, lasers, and simply reflecting sunlight down to solar farms on the ground.

“And we are happy that we have major energy players like the French electricity utility ENGIE and the Italian utility ENEL, included as members of the study consortiums, reflecting the potential value the energy sector is already seeing in this capability for the future.

“It’s important that we engage the energy sector right from the start of this development and listen to their needs, so we know from the beginning that we are building something that end users will want and use.”

The two concept studies are funded by ESA’s Preparation element, part of the Agency’s Basic Activities, which supports new ideas in space missions and technology.

Additionally, SOLARIS funding for technology R&D projects will be made available through ESA’s long-running General Support Technology Programme.

Leopold Summerer, who heads ESA’s Advanced Concepts and Studies Office, said: “These activities demonstrate the importance of ESA’s Preparation element in supporting ambitious ideas to become a reality.

“Preparation-funded activities help ESA assess the interest from European industry in novel topics and lay the groundwork for future research and technology development to make them happen.”

Sanjay added: “There are a lot of fundamental reasons why space-based Solar power is looking a lot more feasible and desirable than ever before.

“These include the reduced cost of launch to orbit with the advent of reusable launchers, the reduced cost of satellite hardware through mass production – seen with new constellations such as Starlink and OneWeb – and trends towards very modular solar power satellite designs.

“In addition, space robotics and in-space assembly and servicing technologies have really come a long way in the last two decades, which will be essential for the construction and maintenance of solar power stations.”

He continued: “Finally, the sheer challenge of transitioning to net-zero within the next 25 years with existing technologies – and the consequences of not doing so – demands exploration of alternative solutions that could help make sure we achieve our goal.”

Main image: An ESA concept for how an orbital solar farm would transmit solar energy collected in space to Earth. Credit: European Space Agency

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