Countries Race to Beam Solar Power From Space

About 30 per cent of incoming solar radiation does not reach the ground, while sunlight in space is constant. Proposed systems would use satellites in geostationary orbit, about 35,000 km above Earth, to transmit power by microwave to large receiving reflectors. These could span up to 3 km and weigh more than 80,000 metric tonnes. Proponents say successful systems could generate multiple gigawatts and supply remote areas without new local power plants or grid extensions.

The microwave beams would require long antennas and, according to the article, could transmit through the atmosphere in any weather at low intensity—barely stronger than midday sunlight. The technology is not expected to interfere with birds or aircraft. China, the United States, the United Kingdom and Japan are pursuing feasibility work through programmes including China’s ZhuRi, the U.K.’s Space Solar and Japan’s OHISAMA. U.S. efforts include projects at Caltech and the Air Force Research Laboratory.

Space Solar plans two demonstration missions: one to transmit power to Earth using radio waves, and another to test robot construction of large structures in space. The U.K. government has provided around $1.6 million. The company’s longer-term concept, Cassiopeia, would be a 1.8km-wide space structure fitted with millions of table-sized satellites, sending power to a ground station the size of Heathrow Airport.

In 2024, Star Catcher demonstrated light transmission across an American football field in Florida. CEO Andrew Rush said the company “beamed 100 watts about 105 metres.” SpaceX has applied to the Federal Communications Commission to launch a constellation of 1 million satellites to power AI data centres. Overview Energy, meanwhile, announced in April plans for a satellite constellation by 2030, aiming to beam 1 GW to Meta’s AI data centres using near-infrared lasers and existing solar panels. Its representative Laura Wetzel said Meta would have “24/7 access to the beam capacity.”

Supporters argue that space-based solar could expand clean electricity supplies and reduce fossil-fuel dependence. Critics say the systems would be prohibitively expensive, rely on many untested assumptions and may not arrive in time to support the green transition. Commercial deployment is now expected between the 2030s and 2050s.