For decades, Space‑Based Solar Power (SBSP) was technically plausible but economically absurd, as NASA’s 1970s estimate suggested the cost of an SBSP demonstrator could have reached $1 trillion. Nowadays, launch costs have fallen sharply, modular satellite designs are maturing, and Net Zero targets are sharpening.
According to a new UK Department for Energy Security and Net-Zero (DESNZ) report, which assessed whether the 2030s could deploy a small-scale system as a stepping stone, the technology could be competitive by 2040. But first, what is space-based solar power, and how does it differ from conventional solar power?
Space‑Based Solar Power: How Does It Work?
SBSP is exactly what it sounds like: solar farms in space. Large satellites in high Earth orbit collect sunlight and beam the energy back down as high-frequency radio waves. Next, a ground-based receiving antenna, called a rectenna, captures the beam and converts it into grid electricity.
The key advantage is location: the satellite sits in geostationary orbit at ~36,000 km above Earth, where sunlight is effectively constant. Wind and solar energy sources, by contrast, are intermittent; when they stop, the only “firm” low-carbon options the UK has are hydro, nuclear, and imports. Assuming SBSP can scale and be cost-effective, it looks promising as a “firm” net-zero power generation option for the UK, since it is effectively an infinite energy source and diversifies the UK’s firm power generation portfolio.
Can We Actually Build It?
SBSP is physically possible, but it isn’t ready to be built yet. The UK’s reference design, called CASSIOPeiA (Constant Aperture, Solid-State, Integrated, Orbital Phased Array), sits at CML (Concept Maturity Level) 4 out of 9 for the space segment, CML 3 out of 9 for the ground segment, and CML 2 out of 9 for robotic assembly.
A major practical constraint is the launch: a single ~2 GW system requires ~2,491 tonnes of spacelift and relies on the assumption that 86–119 Starship‑class launch vehicles will be ready by 2030. If that assumption fails, the rest of the deployment schedule unravels with it.
Another concern is the wireless power transmission. According to Frazer-Nash’s Phase 1 Engineering Report, the Technology Readiness Level is only 3-4 out of 9 levels, as the longest demo thus far is ~1 km. Yet the system is critical because without a multi‑10,000 km wireless power transmission, there is no SBSP at all. The wireless transmitter also carries a “Very High” difficulty rating, alongside in‑orbit assembly and decommissioning, but unlike those, it is a distinctive SBSP technology rather than a capability that can be spun in from wider space robotics or launch. Hence, as of now, SBSP will remain concept‑feasible but commercially unbankable.
What Would It Cost?
The long-run numbers are genuinely attractive, as the initial small‑scale SBSP study projects that a first‑of‑a‑kind (FOAK) constellation in 2030 would have a levelised cost of electricity (LCOE) of around £335–595/MWh, falling to £154–249/MWh by 2035 as learning, launch costs, and hurdle rates improve, and estimated to reach £87–129/MWh for an nth‑of‑a‑kind (NOAK) system by 2040.
Delivering this pathway is estimated to require a development programme of roughly £7.5–16.3 billion over the next 18 years, with 50–77% of that spend needing to come from public funding, yet even the first small‑scale UK system is assessed to deliver a benefit‑to‑cost ratio of 1.81 and to sit within a wider European rollout that could generate a net present value of about £183 billion, rising to £767 billion in scenarios where Net Zero would otherwise be missed between 2022 and 2070.
Among other factors, the LCOE trajectory depends almost entirely on two things:
- Launch costs are falling as forecast, and the hurdle rate drops from 20% (FOAK 2030) to 9.1% (NOAK 2040) as the technology is de-risked.
- Hurdle rate (minimum rate of return) alone accounts for 42% of the reduction in LCOE from FOAK to NOAK. Launch costs account for over 55% of LCOE variance, and that share grows over time as satellite production costs fall.
Private investment alone won’t fund this; without public co-investment, returns fall below the required hurdle rate. Every £100m in grant funding reduces the effective 2030 LCOE by £33.50/MWh. Net benefits hold up even if all SBSP costs are doubled. The bottom line: the economics work on paper, but only if launch costs fall, the hurdle rate follows, and the public sector stays in through the expensive early years.
Launch: The Make‑or‑Break Factor
At today’s technology level, SBSP is far from competitive. For example, in the Caltech CSSPS model, the “current” system comes out at ~780 ¢/kWh, with a total price tag of close to $39 billion, of which $27 billion is for launch alone.
In their mid‑2030s scenario, once the Starship and the hardware mature, the same architecture collapses to about 9.4 ¢/kWh, with a total system cost under 1 billion dollars, of which only about $82 million is for launch. But in the long‑run, with fully optimised designs, costs fall further to roughly 3.8 ¢/kWh, 4.0 US$/W upfront, and a total system cost of around $805 million, with launch down to roughly $33 million.
In other words, most of the journey from “fantastically expensive” to “merely costly” is driven not by radical new physics, but by moving from today’s heavy rockets to a cheap, frequent Starship‑class launcher.
The same pattern shows up in UK studies: once you assume a cheap, frequent heavy‑lift launch, SBSP stops looking like science fiction and starts looking merely expensive; however, if there are problems like the delay of the Starship, estimated 2030 SBSP power costs sit around £600/MWh and only fall to about £145/MWh by 2040, even with other improvements.
Slower technology upgrades or a slower decline in the hurdle rate are painful but less dramatic, keeping 2030 costs in the £540/MWh range and 2040 costs at £162–169/MWh. By contrast, a best‑case launch scenario pulls 2030 costs down to roughly £362/MWh and 2040 costs to about £84/MWh, showing that what happens on the launch pad does more to move SBSP from “unaffordable” towards “potentially competitive” than any other single factor.
The same UK cost modelling report also stated that more than half (55.5-64%) of the uncertainty in future SBSP prices comes from launch costs alone in the 2030s, rising to around two‑thirds by 2040. Rectennas account for only about 14–21% of the variance across 2030–2040, satellite build costs fall from roughly 22% to 8%, and all other capital costs together stay below about 6%.
Furthermore, less mass means fewer launches and, in turn, much lower costs, so the mass‑to‑power ratio of each design really matters. Of the three main concepts on the table, CASSIOPeiA delivers around 2 GW from roughly 2,000 tonnes, an estimated 3-6x greater mass‑specific performance than rivals like SPS‑ALPHA and MR‑SPS because its sandwich modules remove heavy trusses and cabling, and its high‑concentration photovoltaics shrink the required panel area. In parallel, newer cell technologies such as spalled InP (indium phosphide) can reuse the same wafer many times, push the target towards roughly 199 W/kg, and bring panel costs down to roughly $90 per square metre, reinforcing why mass‑efficient designs are central to making SBSP affordable at scale.
In simple terms, most of the uncertainty in SBSP’s future price tag is about how cheap and available big rockets are, as well as the scaling of the technology, and not by how much the hardware on the satellite or the ground ends up costing.
How SBSP Compares to Other Power Sources
The chart shows the levelised cost of energy (LCOE) SBSP today at 335–595 £/MWh based on the UK’s FOAK small‑scale projections, far above mature renewables clustering in the 25–65 £/MWh band across IRENA, Lazard, Mirzahi et al. (2025), and the UK’s in-house report.
However, assuming SBSP goes to plan, the levelised costs drop to levels comparable to offshore wind and approach nuclear, but remain above onshore wind and solar PV. But levelised cost alone isn’t the be‑all and end‑all; if a power source can’t be used when needed, it’s effectively useless. Hence, we need to consider the capacity factor for the next round of comparisons.
Assuming everything goes to plan, SBSP can achieve an 81-95% capacity factor, matching nuclear (90–92%) and geothermal (82%) while vastly exceeding gas CCGT (combined cycle gas turbine) (50–60%), offshore wind (48–50%), onshore wind (26–36%), and solar (11–25%). This reliability positions SBSP as a dispatchable renewable rival to nuclear and geothermal power, unlike intermittent wind and solar power, which require storage or backup. Gas CCGTs’ moderate 50–60% efficiency reflects a flexible role, but SBSP could displace them in decarbonised systems while delivering 3–8x more annual energy per MW than wind or solar.
Even at higher levelised costs (today and in the future), SBSP’s high load factor delivers more MWh per unit of installed capacity than rivals, potentially lowering system LCOE in the long run when paired with storage for intermittent generation.
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Scaling Up and Return-on-Investment
Mass production and scalability are essential to unlock cost reductions. The aerospace sector’s typical learning curve delivers ~15% cost reduction per production batch. SpaceX’s Starlink programme produces approximately 120 satellites per month at under $500,000 per satellite, demonstrating that mass manufacturing of space hardware is achievable, though SBSP would require production volumes far exceeding Starlink’s several-thousand-unit level.
From a carbon perspective, SBSP performs well. System-level lifecycle emissions have been estimated as low as 20 g CO₂eq/kWh, comparable to those of wind and nuclear. At 0.5 GW of installed capacity, the energy payback time falls to under two years, dropping below six months at scale, roughly half that of terrestrial solar. The CASSIOPeiA system would recoup its launch-fuel energy in approximately one day; factoring in the efficiency of green LH₂ production raises this to around three weeks.
What This Means for UK Policy
Space‑based solar power will not replace wind or nuclear, but it could determine whether the UK still has firm, clean electricity on tap when those sources fall short. If the current development pathway holds, a mature system could put SBSP in the same economic conversation as other low‑carbon baseload options rather than as a science‑fiction luxury. That outcome depends less on a breakthrough in physics than on two very specific conditions:
- Whether heavy-lift launch costs continue to fall.
- Whether the cost of capital declines as technologies like the rectenna are de‑risked over time.
Today, SBSP is nowhere near competitive, as current architectures weigh in at hundreds of pounds per MWh and rely on launch vehicles that make the concept unaffordable, with launch accounting for the majority of the total system cost and more than half of future price uncertainty through the 2030s.
As cheaper, higher‑cadence rockets come online, and early demos prove out key technologies such as long‑distance wireless power transmission and in‑orbit assembly, those costs could fall sharply, shifting SBSP from “impossible” to “merely expensive.” At that point, its value lies in what conventional renewables cannot easily provide: an 80–95% load/capacity factor, year‑round, day‑and‑night output, and a way to cut gas generation without relying entirely on very large storage build‑outs.
For UK policymakers, the real question is therefore not whether SBSP is risk‑free, but whether the greater risk lies in trying and failing, or in watching others prove it out while continuing to plug gaps with gas and imports.
Editor’s Note: The opinions expressed here by the authors are their own, not those of Impakter.com — In the Cover Photo: Space based solar panel test concept. Cover Photo Credit: NASA.
