SRC-006

Space solar power generation: A viable system proposal and technoeconomic analysis

Published claims resting on this source

• CLM-0179 This 2025 paper's own numbers show that with today's technology, their space solar power design would cost about $7.78 per kWh - far more expensive than any terrestrial option - and only becomes competitive (9.4 cents/kWh) if 10 years of assumed technology improvement and cost learning happen first.
• CLM-0180 The low headline cost figure in this paper depends on using a very low 2% discount rate borrowed from a US home-energy-efficiency programme, not a rate reflecting the financial risk of building a brand-new kind of space infrastructure - the authors themselves flag that a different, riskier financing situation would need a different (higher) rate.
• CLM-0181 The 9.4-cents and 3.8-cents per kWh figures both depend on launch prices that do not exist yet - they are extrapolated 10 and 20 years into the future from a historical cost-decline trend, using SpaceX's not-yet-finalised Starship costs and a design still based on today's Falcon 9 hardware costs.
• CLM-0296 A 2025 peer-reviewed study from Caltech modelled its own space solar power design and calculated three costs of electricity: about 778 US cents per kilowatt-hour using today's technology, 9.4 cents after about ten years of development, and 3.8 cents in a long-run best case about twenty years out. The 9.4 cents figure that is often quoted is the middle case, not a present-day cost. The design is small, about 113 megawatts, and converts only about 4 percent of the sunlight it collects into electricity delivered on the ground.
• CLM-0297 The low electricity costs in a 2025 Caltech study rest on two assumptions among others. First, it assumes that SpaceX's Starship will in time launch cargo for about 7 million dollars a flight, falling to 3 million, which works out at roughly 128 dollars and then 55 dollars per kilogram. Those are the authors' own projections, built on the way SpaceX said in 2020 that Starship would reach geostationary orbit and on the long-run fall in launch costs, not prices anyone has paid. Second, it assumes that the money to build the system costs 2 percent a year (a 2 percent discount rate), taken from a US government energy memorandum, which the paper itself says reflects one country's funding arrangements at one moment. With the costs and hardware available when it was published in 2025, the same study's own figure is about 778 US cents per kilowatt-hour.
• CLM-0670 Caltech has two different space-solar-power efforts. One is a paper design that assumes a normal rocket-fuel-based trip to a high orbit. The other is a small test that actually flew, but only in low orbit near Earth, testing hardware pieces, not a trip to a higher orbit.
• CLM-1201 Caltech's design has no single large structure. Many separate square craft, each 60 metres across, fly side by side in geostationary orbit and act together as one antenna 1.6 kilometres wide. Each craft is launched rolled up into a drum about 2 metres wide and 1.5 metres tall, and unrolls in orbit.
• CLM-1203 Caltech's receiving station on the ground is a circle about 1.6 kilometres across, just large enough to catch the whole central spot of the beam. Batteries keep its output steady through the short eclipse seasons and the dips while the craft turn.

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