Space power: The dream of beaming solar energy from orbit

Harvesting solar energy in orbit and beaming it down to Earth is a decades-old idea. Now, a raft of companies say they could finally make it a reality.

At an American football stadium in Florida last March, an unusual test took place. Here, it wasn't footballs being thrown, but beams of light across the length of the pitch. The concentrated streaks of light lasted for a few minutes, fired from an emitter on one side of the field in the Jacksonville Jaguars' stadium and collected on a screen on the other.

The light was collected from the Sun and them beamed out by large lenses on the field like a magnifying glass, each about 1.2m (4ft) tall. "We had to get up a ladder to pull the cover off," says Andrew Rush, president and chief executive of the Florida-based company Star Catcher that carried out the test.

The goal? To see if beaming sunlight across space to power satellites was feasible.

"We knew some folks at the Jaguars and we thought this would be a cool thing to do," says Rush. "We beamed 100 watts about 105m [345ft]."

Star Catcher is one of several companies around the world developing space-based solar power technologies, a concept that has languished in a grey area between science fact and science fiction for decades. The idea is to provide Earth with abundant clean energy by capturing sunlight in space and beaming it to the ground or other satellites.

Solar panels on terra firma are, by contrast, limited by the atmosphere, the weather and Earth's day-night cycle. These all affect how much sunlight those panels can soak up, filtering out varying amounts of the Sun's radiation before it can reach ground level. But in space, it is possible to collect sunlight almost around the clock at much higher efficiencies.

"I remember telling my father about this and he thought I was a bit bonkers," says David Homfray, co-founder and chief technology officer of UK firm Space Solar. But multiple countries, including the UK, US, Japan and China are now investing in the technology.

Star Catcher

"Space-based solar power makes the energy transition work," argues Homfray, noting that some estimates claim it could supply up to 80% of Europe's renewable energy needs.

This is largely due to the higher power density – more than 10 times higher – that space-based solar has compared to those based on the Earth's surface – it can convert far more of the Sun's energy into electricity.

And yet realising it is no mean feat.

It would likely require enormous satellite constellations, which might be controversial, difficult to operate safely and require a significant number of rocket launches to construct. Plus, there are cheaper and easier forms of renewable energy that could come online far quicker – which is important given the need to replace fossil fuels with greener alternatives if the world is to have any hope of bringing global warming under control.

Even so, there are some who believe the rewards for building solar power stations in space will come to far outweigh the drawbacks. The US military, for example, is very keen on a technology that will allow it to beam energy to anywhere in the world on demand, helping to overcome one of the major problems faced on modern battlefields, but it could be equally as useful in the aftermath of disasters or for rural communities.

Space-based solar power works much like solar on Earth – panels convert sunlight into electricity – but with one huge advantage: they're above the atmosphere. This means those panels can collect sunlight that hasn't been filtered through the gas and clouds that cloak our planet. The atmosphere reflects around 30% of the energy that reaches our planet while it absorbs around a quarter before it even reaches the Earth's surface. Space-based solar panels can avoid this effect, but can remain in near-constant sunlight if placed in the right orbit.

Once collected, this power can be transmitted to Earth as microwaves or laser beams, and captured by large ground antennas that convert it back into usable electricity. To make economic sense, however, each satellite must generate and beam immense amounts of power at gigawatt scale, requiring massive arrays assembled in orbit.

US science-fiction author Isaac Asimov first wrote about tapping solar energy from space in 1941, in a short story called Reason. Later, in the 1970s, studies by Nasa concluded that, while it was intriguing, there were major technological and economic barriers.

John Mankins, a former Nasa physicist and proponent of space-based solar power, led another study in the 1990s that suggested the idea was becoming more practicable due to advances in solar cells and other technologies. "It was a change in feasibility from $1tn to $100bn, [£750bn to £75bn]," he says. "But it was not an era when anyone was interested in that."

Space-based solar was "extraordinarily polarising 30 years ago", says Mankins. "People either loved it and they were passionately in favour of it, or they absolutely hated it."

Over the past decade, however, things have changed, says Mike Curtis-Rouse at UK-based research organisation Satellite Applications Catapult. "We've seen an upswell in the amount of interest," he says.

This has, in part, been driven by the falling cost of launching objects into space and the arrival of huge new rockets such as SpaceX's Starship, which is undergoing testing in Texas. Advancements in satellite manufacturing, robotics and power-beaming technology have also brought the prospect of space-based solar into view.

"We're kind of reaching that critical mass point," says Curtis-Rouse. "I'm reasonably confident we'll see space-based solar capability in orbit within the next two decades."

In 2023, the UK government awarded £4.3m ($5.7m) in funding to multiple companies working on space-based solar power.

In China, scientists are working on a prototype space solar-power satellite called Omega 2.0, which uses microwaves to transmit the power from an array of solar panels. They propose assembling a 1km-wide (0.6 miles) antenna in orbit along with 600 solar sub-arrays that each measure 100m (330ft) wide. Tests on the ground have so far managed to transmit up to 2,081 watts – enough to power a kitchen kettle – over a distance of 55m (180ft) using the microwave transmission technology.

ESA

The European Space Agency's Solaris initiative is also due to make a decision later this year on whether space-based solar is worth investigating further. In the US, several companies are developing space-based solar-power technologies with funding from the US military.

"It's a lot closer to reality than a lot of people think," says Michelle Hanlon, a space lawyer at the University of Mississippi. "Once you make that initial investment, that power is literally free. So it's about having the wherewithal and vision to make that investment."

One company working on the technology is Aetherflux, a start-up based in California.

"Space-based solar power is this fantastical idea," says founder Baiju Bhatt. "The question behind the company was, if you want to do this today – not in 2050, but in the next two to three years – what is the approach you would take?"

Aetherflux intends to deploy a fleet of satellites equipped with high-powered infrared lasers and photovoltaic cells into low Earth orbit. These satellites would collect solar power before it is then beamed down to Earth to collection points on the ground measuring perhaps just 5-10m (16-33ft) across, giving them a relatively small footprint. As a safety precaution, each laser would be designed to turn off instantly should anything fly into its path, such as an aircraft or another satellite, in case it damaged their sensors or occupants.

The lasers are too weak to cause significant damage – they aren't going to break a plane in two, for example – but are powerful enough that their health effects do need to be considered, says Curtis-Rouse.

"The aspiration is not to build a Death Star," says Curtis-Rouse. "The reality is the energy would take a while to fry an egg. That way things can pass through it – birds, planes, Superman, whatever the case may be."

The technology could be useful for energy-starved locations, says Bhatt, with the military a potential key early adopter. "The US government has huge energy needs all around the world," he says.

Alamy

In April, Aetherflux announced that it had raised $50m (£37m) in funding. The firm plans to launch a demonstration satellite in 2026 that will practise beaming a 1kW or 1.3 kW laser to solar panels on the ground. "The best-case scenario is we'll see a couple of hundred watts of power," says Bhatt.

The company has yet to release any details about how its infrared laser transmission system performs in tests on Earth.

Space Solar in the UK is taking a different approach – it envisages giant solar power stations in space the size of cities that could beam down enough energy to power entire countries. It's a monumental task, but one that Homfray believes is possible.

"By 2050, there's no reason not to expect space-based solar power doesn't provide 20% of all global power," he says.

Space Solar, which received about £1.2m ($1.6m) in UK government funding, plans to launch two demonstration missions during the next three years, one to practise transmitting power to the ground via radio waves, and another to show how robots could build large structures in space.

Eventually, the company says, it wants to construct a giant 1.8km-wide (1.1 miles) structure in space which it plans to call Cassiopeia. Positioned about 36,000km (22,000 miles) above Earth in geostationary orbit, meaning it always remains above the same spot on the planet and in near-constant daylight, the station would use millions of table-sized satellites covered in solar panels to collect incoming sunlight. Roughly a billion antennas would beam the collected power to a receiving station on the ground the size of Heathrow Airport, which would in turn convert the radio waves into electricity.

"If you had a dozen of those in the UK, that would probably cover the UK's entire energy needs," says Curtis-Rouse.

Space Solar

One Cassiopeia could have a capacity of around 700 megawatts says Homfray, enough to power half a million UK homes and about a quarter of the energy output of the Hinkley Point C nuclear power station currently under construction in Somerset.

Earlier in 2025, Space Solar announced it had built a robotic demonstrator for constructing the structures its technology will need in space. Last year the company demonstrated a 360 degree wireless energy transmission in a laboratory at Queen's University Belfast, in Northern Ireland.

The US company Virtus Solis is also working on space-based solar power technology. It would group 200,000 honeycomb-shaped satellites together in vast constellations spanning multiple kilometres. Those constellations would have unusual Molniya orbits that swing widely around the planet, enabling them to spend long periods over high latitudes to beam power to the northern hemisphere. Virtus Solis plans to launch a demonstration mission in 2027.

If successful, chief executive and founder John Bucknell says, energy costs on Earth could drop dramatically. "The global average for electricity is about $75 [£55] per megawatt hour," he says, whereas space-based solar power could eventually offer electricity at $0.50 [£0.40] per megawatt hour based on the company's modelling. "So for you, me, everyone – our annual energy use is about $10 [£7] in that category," says Bucknell. "That's what our goal is."

Some, however, do not agree that space solar power can be delivered at low cost. One assessment of large-scale space-based solar power designs suggests electricity produced in this way could cost 12-80 times more than Earth-based alternatives.

Spacecraft could one day beam power to other places besides Earth. Star Catcher – the company behind the test at the NFL stadium in Florida – is looking into whether it might one day redirect sunlight to satellites, giving them a power boost in space.

Their beam system would use a series of Fresnel lenses – the kind lighthouses have long used to reflect and refract light – to focus sunlight onto the solar panels of satellites. Rush says the technology could give satellites more power than they can obtain from natural sunlight alone.

"They get power when the Sun is shining on them, and when it's not they don't have any power generation," he says. "What we're doing is transmitting to those satellites. […] We can vary the intensity from one Sun to ten Suns."

Star Catcher

Such a system could also help supply energy to rovers on the Moon, which must survive lunar nights lasting up to two weeks, says Rush.

But not everyone is convinced by space-based solar power. One concern is the challenge of launching and operating so many satellites in space, something never attempted on the extremely large scale proposed by space-based solar firms.

Managing hundreds or thousands of satellites stitched together, and stopping them colliding with other satellites, is a big challenge says Francesca Letizia, a space debris expert at the European Space Agency in The Netherlands. Any accidents could quickly pour cold water on the nascent industry. "Even a few events would be really detrimental," she says.

Plus, such large constellations may not even be legal, says Hanlon. Under the Outer Space Treaty of 1967, no country is allowed to claim ownership of any parts of Earth orbit. "Does that change when we're talking about a square-mile array?" says Hanlon. "I would think if China announced it's going to have 4 sq miles [10 sq km] of satellites, the US is going to complain."

Whether space-based solar power is really achievable is another question. A 2024 Nasa report said that the technology currently remains far more expensive than terrestrial renewables and was possible only with major advances in launch, manufacturing, and efficiency.

"We're certainly in a better spot than we were 30 years ago," says Charity Weeden, a former Nasa Associate Administrator for technology, policy and strategy, and a space policy expert. "But are we at the precipice of, like, let's go do this?"

Karen Jones, a space economist and technology strategist at The Aerospace Corporation, a US non-profit, says international cooperation will likely be needed to make space-based solar work: "This is carbon-free energy," she says. "Let's hope it happens, because right now there's a lot of distrust in space."

Such an initiative might mirror the collaboration that supported the construction of the International Space Station (ISS), which is itself the size of a football pitch.

"You could have a single investment in space-based solar power over the equator," says Mankins. "Depending on the demand, it could beam power to Poland, to London, to Riyadh, to Cape Town – and it could switch multiple times a day."

Countries that need power during a crisis, such as after a major hurricane, could also benefit – a temporary lifeline before they get their electricity grids working again. "You could beam even smaller amounts of power to hospitals, and so on," says Jones.

Star Catcher is planning its next major test soon, not on an American Football pitch, but on a runway once used by Nasa's Space Shuttle at Cape Canaveral in Florida. It would set a new record for transmitting power wirelessly.

"We're going to beam power multiple kilometres down that runway," says Rush.

Whether this fascinating technology will ever manage to take off, though, remains a big question.

* This article has been updated on 31 October 2025 to correct some information about Aetherflux's technology. We incorrectly stated that the laser it would use would be 1km wide, when in fact it should have been a 1kW laser. We have also corrected the size of the receiver on the ground they will use from 10-20m to 5-10m.

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