Elon Musk has proposed launching AI datacenters into orbit, powered by solar arrays. He claims space will become the cheapest location for AI compute within 30-36 months.12 The physics of orbital solar are sound—roughly 5× the energy capture of terrestrial panels12 with no weather, no night cycle (in sun-synchronous orbits), and radiative cooling is at least plausible.
But a complete thermodynamic accounting reveals a structural constraint that the economic framing obscures: the plan has an extremely high dependence on Earth's electrical grid. Manufacturing the panels alone consumes grid electricity on the same order of magnitude as the orbital array's annual output—and none of that grid energy is ever returned to Earth.
This analysis computes the total energy investment required to place one Starship payload of solar panels into orbit and expresses it as a fraction of the array's annual orbital energy output. It does not include any grid capacity for terrestrial AI datacenters—the gigawatts xAI and others are already racing to build on the ground. That demand is additive to everything below.
Every number on this page is derived from the assumptions below—change them and watch the entire analysis recalculate.
SpaceX's Starship delivers 100 tonnes to low Earth orbit. At 100 W/kg, one launch places 10 MW of solar generating capacity into orbit.
At a 55% capacity factor (LEO), this array produces 48,180 MWh in its first year—equivalent to running a 5.5 MW plant 24/7.
Three categories of energy are consumed to get those panels generating in orbit:
Producing solar panels—mining quartz, purifying polysilicon at >2,000°C, crystal growth, wafer sawing, cell fabrication—consumes 4.5 kWh for every watt of capacity. Nearly all of this is grid electricity.
The full Starship/Super Heavy stack carries 4,900 tonnes of propellant: 3,870 t of LOX and 1,030 t of liquid methane.7 Burning that methane releases 14,343 MWh of chemical energy. This is a fixed cost per launch regardless of payload, and it's a directly extracted resource—it doesn't show up in the grid bill unless propellant has to be synthesized.
| Component | MWh | Type | % of Year 1 |
|---|---|---|---|
| Panel manufacturing | 45,000 | Grid electricity | 93.8% |
| Propellant chemistry | 14,343 | Fossil fuel | 29.8% |
| Ground operations | 2,304 | Grid electricity | 4.8% |
| Total | 61,647 | 127.9% | |
| Annual orbital output | 48,180 | 100% |
The metric that matters is grid EPBT: how long the orbital array must operate to generate energy equal to what Earth's grid invested. We exclude the chemical energy of propellant—that's drawn from fossil methane reserves, not the grid—and focus on what the grid actually supplies: manufacturing energy plus ground operations.
For comparison, modern terrestrial solar panels achieve EPBT of 0.5–1.2 years10. At your current settings, orbital solar's grid EPBT is 0.98 years—comparable to terrestrial solar.
If the panels last 10 years before replacement, Earth must re-invest the full energy budget each cycle. Over 30 years the grid bears this cost 3×, with zero energy return.
Musk states both Tesla and SpaceX have a mandate to reach 100 GW/year of solar cell production.6 He projects eventually deploying hundreds of GW per year into orbit, reaching a terawatt per year.12 At your target of 100 GW/year:
Each launch delivers 10 MW, so 100 GW/year requires 10,000 launches per year—1.14 launches per hour, continuously.
Building 100 GW of panels per year at 4.5 kWh/W requires 51.4 GW of continuous grid power just for manufacturing.
For context, average US electricity generation is ~480 GW.11 Manufacturing alone would consume:
Bar represents fraction of US average grid generation (~480 GW)
10,000 launches × 1,030 t methane = 10,300 thousand tonnes per year, or roughly 500 Bcf of natural gas—1.4% of US production. Surprisingly plausible given the scope of the project.
Adding ground operations, the total continuous grid draw is 53.0 GW—11.0% of US generation capacity. This is equivalent to the entire electricity output of a major industrial nation, dedicated permanently to building hardware for space, with no energy return to Earth.
Musk's thesis is that terrestrial grid capacity is the bottleneck for AI scaling. His solution requires massive amounts of that same bottlenecked grid to manufacture and launch orbital panels.
Every GW/year of orbital deployment requires 0.53 GW of dedicated terrestrial grid power. To deploy at Musk's target of 100 GW/year, you need 53.0 GW of grid capacity that does nothing but build space hardware.
If the US could allocate 50 GW of surplus grid capacity to this effort (a generous estimate—that's more than the entire output of New York State), maximum orbital deployment would be 94 GW/year. At a more realistic 10 GW surplus: 19 GW/year.
Despite the grid dependence, the lifetime energy math is compelling. Over 10 years, that orbital array generates far more energy than the grid invested to create it:
For every MWh the grid invests, the orbital array delivers 10.2 MWh of compute capacity in orbit over its lifetime. This isn't about dollar arbitrage—it's about capacity multiplication. The grid spends 47,304 MWh and gets 481,800 MWh of orbital compute in return.
When grid capacity is the binding constraint on AI scaling, a 10× multiplier on grid electricity—even one that never returns to Earth—is a powerful lever.
Musk's strongest point is not physics but bureaucracy: no land permitting, no NIMBY opposition, no utility interconnection queues. This is likely correct in the near term. But it means orbital compute is routing around Earth's political constraints while remaining entirely dependent on Earth's grid for manufacturing and propellant.
Orbital solar doesn't solve Musk's energy problem. It relaxes it.
The 10.2× lifetime multiplier is real: the grid trades 47,304 MWh per launch for 481,800 MWh of orbital compute over 10 years. That's a genuinely powerful lever—but the capacity arrives over a decade, and in a scaling race where the next 2-3 years matter most, energy delivered in year 8 may not matter.
But every GW of orbital compute still requires 0.53 GW of dedicated terrestrial grid to manufacture and launch. At 100 GW/year, that's 53.0 GW—11.0% of US generation—building space hardware. Manufacturing alone accounts for % of the energy bill; the conversation about launch cost per kilogram is a sideshow.
And this is before counting a single watt of terrestrial AI datacenters. The grid capacity above is only for manufacturing and launching space hardware—it doesn't include the gigawatts xAI and others are already building on the ground. That demand is additive.
Musk still has to desperately figure out electricity on Earth to ramp datacenters in space. Orbital solar is a bet that it's easier to build power plants and solar factories than to permit, interconnect, and build transmission for equivalent terrestrial compute. That's probably right. But the path to space compute runs through exactly the same terrestrial energy buildout that Musk says is too slow—it just needs less of it.