Researchers are working on ways to put solar farms in orbit above the Earth.
The intermittency of solar power is driving interest in the bold idea of harvesting energy in space.
A team of researchers in the US has proposed a viable system for space solar power (SSP) that could beam clean, dispatchable energy back to Earth and compete economically with today’s cheapest energy sources.
Originally imagined in the 1940s, SSP involves placing solar arrays in geostationary orbit to collect sunlight 24/7 and transmit power wirelessly to ground stations.
The concept has faced insurmountable hurdles in cost, weight and complexity, but “recent progress in photovoltaic technology, high-frequency integrated circuits, and a reduction in launch costs bring SSP within reach”, researchers say in a new paper, published in Joule.
The proposed Caltech Space Solar Power System (CSSPS) features lightweight, flexible modules fitted with high-efficiency solar cells and radio frequency transmitters.
These modules, launched in compact coils, deploy in orbit and work together to form steerable energy beams targeting terrestrial receiving stations.
“Our analyses demonstrate that with 10 years of technology development, maturation, and scaling, the proposed 10 [gigahertz] system can deliver electricity at 9.4 [US cents per kilowatt-hour] – competitive with the cheapest clean energy sources available today,” the authors say.
Each module integrates thin-film indium phosphide (InP) solar cells with wireless power transfer electronics, supported by ultralight composite structures.
Crucially, the system avoids heavy DC wiring by co-locating power generation and transmission, with advanced RFICs converting solar-generated DC into phase-synchronised microwave beams.
The authors estimate a 113-megawatt (MW) system with 559 modules could cost around US$983 million to build and operate over 15 years – achieving a levelised cost of energy (LCOE) close to utility-scale wind and hydro.
Compared to traditional renewables, SSP offers unique advantages: constant power availability, no weather dependence, and the ability to dispatch energy to any location.
While still theoretical, the system’s feasibility is underpinned by recent in-orbit demonstrations of key technologies.
The team argues that, given the global urgency for clean, reliable energy, “SSP would offer power 3 [times] cheaper than the current global average with potentially much greater flexibility.”
As launches become cheaper and component technologies mature, the researchers say that the idea of orbiting solar parks is shifting from visionary to viable.