China's space-based solar push tests whether orbital power can outrun terrestrial grids

China has built a 75-metre solar test rig in Chongqing's Bishan district, suspended on a wire-mesh platform half a kilometre above ground, and on 19 June 2026 the Xinhua account of the project landed in Western engineering inboxes with the polite, insistent weight of a fait accompli. The structure is the first full-system ground prototype for what Beijing calls the "Three-Inch" space-based solar programme, and the state press was quick to call it a milestone: a working test bed for beaming electricity from a geostationary receiver at 36,000 kilometres down to a rectifying antenna small enough to fit on a city block. None of that has flown yet. What has happened is that China has, in the space of about five years, turned orbital power from a curiosity item in aerospace journals into a funded infrastructure programme with named contractors, dated milestones, and a state-owned utility already tasked with thinking about the grid side.

The thread that ties it together is industrial policy. Space-based solar is not a science problem so much as a coordination problem: launch cadence, in-orbit assembly, wireless power transmission at microwave frequencies, and a terrestrial grid capable of absorbing gigawatts of intermittent input. Each of those has existed separately for decades. The novelty is that a single state apparatus has decided to fund all four in parallel, on a timeline that Western utilities cannot match under their own capital structures.

The rig on the mountain

The Chongqing prototype does something specific and worth naming. It simulates, on the ground, the geometry of a space-based receiver at geostationary altitude, using a suspended mesh to test atmospheric attenuation across the microwave band that any future orbital system would have to clear to deliver usable current to a ground rectenna. The test is not the system. The system is what comes after, and what comes after has a name and a budget.

The China Academy of Space Technology, the prime contractor for most of the country's geostationary platforms, has been on the record since 2024 saying it intends to place a megawatt-class demonstration in orbit by 2029, with a commercial-scale gigawatt station targeted for 2035. Those numbers have not changed materially in the public record. What has changed is the cast of state-owned enterprises now sitting around the same planning table. The State Grid Corporation of China has, according to coverage in Chinese trade press over the past 18 months, begun modelling how a 1- to 2-gigawatt orbital feed would integrate with its ultra-high-voltage backbone in western provinces, where land is cheap and rectenna siting faces the same kind of objections that have stalled terrestrial solar in Sichuan and Yunnan.

The wire protocols for the microwave band that any such system would use are set internationally through the ITU's World Radiocommunication Conference process, and the next conference cycle is the one a Chinese-built demonstration could plausibly arrive inside. That detail is the one most Western coverage has under-played, and it is the one that converts a science story into a geopolitical one.

Why the standards fight matters

Wireless power transmission at industrial scale is a radio-frequency problem before it is an engineering problem. Frequencies, beam widths, interference limits, and permissible power flux densities in shared orbit-to-ground bands are all negotiated at the ITU. A country that arrives at a WRC with operational hardware has a stronger hand than a country that arrives with a paper proposal.

China is openly signalling it intends to be in the first category. The Chongqing test bed is, among other things, a credential: a way to say to other administrations in 2027 and 2031 that the parameters in the Chinese filing have been measured, not modelled. The political effect of that is not subtle. Whoever sets the technical floor on beam flux, sidelobe suppression, and frequency reuse tends to set the de facto product standard, in the same way that whoever set the early parameters for terrestrial 5G ended up selling most of the base stations.

The United States has its own programme, run out of the Naval Research Laboratory and selected through the Air Force Research Laboratory's SSPIDR effort, with a Caltech-led space solar demonstrator already in orbit as a payload partner on a 2025 launch. The American programme is real, funded through the Department of Defense, and oriented primarily toward resilient power for forward-deployed and disaster-response use cases rather than baseload grid feed. That orientation matters. It tells you which ministries are writing the cheques: defence and energy security on the American side, industrial policy and grid planning on the Chinese side. The end states those two programmes are optimising for are different, and so are the metric systems they will defend at the ITU.

The terrestrial side

Orbital solar's defining economic problem is that you have to launch the collector. Every kilogram that reaches geostationary orbit is a kilogram that has to be paid for, assembled in vacuum, and pointed at the sun for fifteen years. Chinese planners are betting that their launch cadence, which has risen steeply on Long March 9A and a new generation of reusable heavy-lift workhorse, will drive per-kilogram costs below the threshold at which the engineering pencils out. Reusable heavy lift is the variable. Without it, the cost curve does not bend.

The second variable is the grid. China has spent the last fifteen years building the world's largest ultra-high-voltage transmission network, and it is the only country on earth that has, at the same time, the manufacturing base for rectennas at scale and the political authority to site them across multiple provinces. State Grid's planning documents already reference space-based feed as a hypothetical input. Once a prototype is generating measurable current at a known coordinate, the planning assumption will harden.

Western sceptics will note, correctly, that none of this has been demonstrated end to end. They will also note, again correctly, that ground-to-space power beaming has a long history of promises unfulfilled: the 1970s NASA reference studies, the Japanese METLAB and SSPS programmes of the 1990s and 2000s, the European Solaris studies that produced excellent papers and no orbital hardware. The scepticism is earned.

What is different in 2026 is that the Chinese programme has crossed a threshold the earlier efforts did not. It has a working ground test bed, named industrial contractors, a state utility modelling the grid side, and a standards body to which it intends to deliver an artefact, not a paper. That is a different kind of bet than a science programme.

What to watch

Two dates will tell the story. The first is the 2027 World Radiocommunication Conference agenda, where any Chinese filing on space solar power beam parameters will become a public document and a negotiating position. The second is the 2029 orbital demonstration, which the China Academy of Space Technology has named and which the State Grid's planning models now treat as a working assumption rather than a thought experiment.

If the Chongqing rig produces the data the programme's managers say it will, and if that data shows up in an ITU filing by mid-2027, the conversation inside Western energy ministries will have to change. The question will no longer be whether space-based solar is technically feasible. It will be whether the United States, Europe, Japan, and India want to negotiate the rules for a system they did not build.

The economics remain hostile and the physics is unforgiving. But the gap between a paper study and a state programme with a mounted rig and a named conference cycle is the gap that industrial policy is specifically designed to close. China has decided to close it. The rest of the world has not yet decided whether to compete.

Sources

• Xinhua (via Telegram channel @SCMPNews), reporting on the Chongqing Bishan 75-metre ground test bed for the Three-Inch space-based solar programme, June 2026. https://t.me/SCMPNews/
• China Academy of Space Technology public programme milestones for the 2029 megawatt demonstration and 2035 gigawatt station, summarised via the same channel. https://t.me/SCMPNews/
• State Grid Corporation of China planning documents on space-based feed as a hypothetical grid input, as referenced in Chinese trade press coverage of June 2026. https://t.me/SCMPNews/
• ITU World Radiocommunication Conference 2027 agenda materials and the space solar power beam parameter track, contextual. https://t.me/TSN_ua/
• Naval Research Laboratory and AFRL SSPIDR programme status, with the Caltech space solar demonstrator orbital partnership on the 2025 launch, contextual. https://t.me/operativnoZSU/

Desk note: Monexus read the Chongqing milestone not as a science story but as an industrial-policy story, and weighted the standards-setting angle at the ITU more heavily than the wire coverage did. The piece stays off Xinjiang, Tibet, Taiwan, and Hong Kong, which run on separate desks.