Summarizer

> it is possible to put 500 to 1000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the Sun’s power We currently make around 1 TW of photovoltaic cells per year, globally. The proposal here is to launch that much to space every 9 hours, complete with attached computers, continuously, from the moon. edit: Also, this would capture a very trivial percentage of the Sun's power. A few trillionths per year.

We also shouldn't overlook the fact that the proposal entirely glosses over the implication of the alternative benefits we might realize if humanity achieved the incredible engineering and technical capacity necessary to make this version of space AI happen. Think about it. Elon conjures up a vision of the future where we've managed to increase our solar cell manufacturing capacity by two whole orders of magnitude and have the space launch capability for all of it along with tons and tons of other stuff and the best he comes up with is...GPUs in orbit? This is essentially the superhero gadget technology problem, where comic books and movies gloss over the the civilization changing implications of some technology the hero invents to punch bad guys harder. Don't get me wrong, the idea of orbiting data centers is kind of cool if we can pull it off. But being able to pull if off implies an ability to do a lot more interesting things. The problem is that this is both wildly overambitious and somehow incredibly myopic at the same time.

That’s not the point of the person you are replying to. They are saying if we somehow come up with the tech that makes harnessing the sun a thing, the best we can still do is put a bunch of GPUs in space? It makes no sense.

It kinda does make sense if you consider that solar panels in space have been used for a very long time (to power satellites). However, getting the electricity they generate down to Earth is very complicated, so you end up having to use it in space, and one of few things that would make sense for that is indeed data centers, because getting the data to Earth is easier (and Elon already handily has a solution for that). However I'm curious how many solar panels you would need to power a typical data center. Are we talking something like a large satellite, or rather a huge satellite with ISS-size solar arrays bolted on? Getting rid of the copious amounts of heat that data centers generate might also be a challenge ( https://en.wikipedia.org/wiki/Spacecraft_thermal_control )...

A 10MW data center would require square kilometers of solar arrays, even in space. It’s just as real as the 25k Model 3.

0.2 sq km approx.

Sending post-compute radio waves to Earth is much safer than sending back TW of power.

That's even more reason that if we manage to increase the amount of solar energy cells by 1000x there are so many more effective ways to use it than immediately flinging them into space. They're not getting constructed as satellites mid-orbit, after all.

OK, so what are they? Scaling photovoltaic production doesn't seem likely to have many broader implications on its own. At best, it makes it easier to change the grid to renewable power, if you ignore the intermittency problem that still exists even at huge scales. PV fabs aren't really reusable for other purposes though, and PV tech is pretty mature already, so it's not clear what scaling that up will do. Scaling rocketry has several fascinating implications but Elon already covered many of them in his blog post. Scaling AI - just read the HN front page every day ;) What are we missing here? Some combinatoric thing?

> doesn't seem likely to have many broader implications on its own Considering how foundational energy is to our modern economy, energy several orders of magnitude cheaper seems quite likely to have massive implications. Yes it might be intermittent, but I'm quite confident that somebody will figure out how to effectively convert intermittent energy costing millicents into useful products and services. If nothing else, incredibly cheap intermittent energy can be cheaply converted to non-intermittent energy inefficiently, or to produce the enablers for that.

Scaling up PV production to the point where we could convert the entire Earth's electricity generation to solar is incredibly significant. Yes there's the problem of intermittency, varying sun availability and so forth - which is why solar will never provide 100% of our power and we'll also need grid-scale storage facilities and domestic batteries and all sorts of stuff - but just imagine being able to make that many panels in the first place! Literally solar on every roof, that's transformative. But sure, let's send it all to space to power questionable "AI" datacentres so we can make more fake nudes.

> Scaling photovoltaic production doesn't seem likely to have many broader implications on its own Musk is suggesting manufacture at a scale sufficient to keep the Earth's entire land area tiled in working PV. If the maths I've just looked at is correct (first glance said yes but I wouldn't swear to it), that on the ground would warm the earth by 22 C just by being darker than soil; that in the correct orbit would cool it by 33 C by blocking sunlight.

Just scratching at the surface, assuming the increase in production capacity is only realistically possible if you can bring prices down (or this "project" would start to consume a proportion of economic output large enough to seem implausible), you can address the intermittency problem in several ways: Driving down the cost makes massive overprovision a means of reducing the intermittency because you will be able to cover demand at proportionally far lower output, which also means you'll be able to cover demands in far larger areas, even before looking at storage. But lower solar costs would also make storage more cost effective, since power cost will be a lower proportion of the amortised cost of the total system. Same with increasing transmission investments to allow smoothing load. Ever cost drop for solar will make it able to cover a larger proportion of total power demand, and we're nowhere near maximising viable total capacity even at current costs. A whole lot of industrial costs are also affected by energy prices. Drive down this down, and you should expect price drops in other areas as well as industrial uses where energy expensive processes are not cost-effective today. The geopolitical consequences of a dramatic acceleration of the drop in dependency on oil and gas would also take decades to play out. At the same time, if you can drive down the cost of energy by making solar so much cheaper, you also make earth-bound data centres more cost-competive, and the cost-advantage of space-bound data centres would be accordingly lower. I think it's an interesting idea to explore (but there's the whole issue of cooling being far harder in space), but I also think the effects would be far broader. By all means, if Musk wants to poor resources into making solar cheap enough for this kind of project to be viable, he should go ahead - maybe it'll consume enough of time to give him less time to plan a teenage edgelor - because I think the societal effects of driving down energy costs would generally be positive, AI or not, it just screams of being a justification for an xAI purchase done mostly for his personal financial engineering.

Okay but even in that case the hardware suffers significant under utilisation which massively hits RoI. (I think I read they only achieve 30% utilisation in this scenario)

Why would that be the case if we assuming the grid prioritizes the data centers?

Starlink yes, at 480 km LEO. But the article says "put AI satellites into deep space". Also if you think about it, LEO orbits have dark periods so not great. A better orbit might be Sun Synchronous (SSO) which is around 705 km, still not "deep space" but reachable for maintenance or short life deorbit if that's the plan. https://science.nasa.gov/earth/earth-observatory/catalog-of-... And of course there are the LaGrange points which have no reason to deorbit, just keep using the old ones and adding newer.

With zero energy cost it will run until it stops working or runs out of fuel, which I'm guessing is between 5-7 years.

Reliably and efficiently transport energy generated in space back to earth, for starters Or let me guess, its going to be profitable to mine crypto in space (thereby solving the problem of transporting the "work" back to earth)

Overview energy has done interesting work in this area.

Beaming energy always sucks. Without some very fundamental discoveries in physics nobody will every make this work economically. This isn't just an engineering problem, it's a physics problem.

Beaming energy does suck, but it might be something to do before we launch thousands of terawatts of GPUs to space.

It's always better to generate electricity on the ground than attempt to beam it to the ground from space. The efficiency loss of beamed power is huge.

The efficiency loss of nighttime is approximately 100% if we’re talking about solar energy. At least at a most basic level, it’s not totally absurd to stick some kind of power beaming contraption in space where it is mostly not shadowed by the Earth and beam power to a ground station.

Is that more or less absurd than making deals with our neighbours to share their electricity? Build some solar farms around the planet and then distribute it over wire. I honestly don't know the answer. I know there's some efficiency loss running over long wires too but I don't know what's more realistic.

In theory you can do HVDC over long distances. In practice that doesn't help much. Power would normally want to run north to south (not gonna do HVDC across the oceans anytime soon), and so the terminator hits you at the same time everywhere. It's got to be batteries if you want PV at scale. The practical difficulties aren't really long distance transmission though. They're political and engineering. Spain had a massive blackout recently because a PV farm in the south west developed a timing glitch and they couldn't control the grid frequency - that nearly took out all of Europe and the power wasn't even being transmitted long distance! The level of trust you need to build a giant integrated continent-wide power grid is off the charts and it's not clear it's sustainable over the long run. E.g. the EU threatened to cut Britain's electricity supplies during Brexit as a negotiating tactic and that wasn't even war.

HVDC would be a lot less connected than an AC grid. The real question is, why do you expect Space to have fewer political and engineering issues.

There is absolutely nothing realistic about power transmission from space to earth, wired or wireless.

I concur it’s not necessarily totally absurd — but when you consider that such contraptions require large — very large! — receiving arrays to be built on the ground, it’s hard to avoid concluding that building gigantic photovoltaic arrays in, say Arizona (for the US) along with batteries for overnight buffering and transmission lines would still be massively more efficient.

We have these things called batteries, you charge them during the day, and drain them at night. A solar+battery setup is already cheaper than a new gas plant. Beaming power from space is absolutely asinine, quite frankly. The losses are absurd, the sun already does it 24/7, and we know how to make wires and batteries to shuffle the sun's power around however we need to. Why on earth would we involve satellites?

Why would you transfer the energy to earth? The energy powers ai compute = $

Nothing about this is sounding economically competitive with ground based solutions

Not sure why this is downvoted. Much cheaper to transfer data than energy.

If we (as in "civilization") were able to produce that many solar panels, we should cover all the deserts with them. It will also shift the local climate balance towards a more habitable ecosystem, enabling first vegetation and then slowly growing the rest of the food chain.

> It will also shift the local climate balance towards a more habitable ecosystem, enabling first vegetation and then slowly growing the rest of the food chain. Depends on the deserts in question and knock-on effects: Saharan Dust Feeds Amazon’s Plants. * https://www.nasa.gov/centers-and-facilities/goddard/nasa-sat... Helping vegetation in one place to grow may hinder it somewhere else. How important this is still appears to be an open question: * https://www.nature.com/articles/s43247-020-00071-w I'm not sure if humans are wise enough yet to try 'geo-hacking' (we're already messing things up: see carbon dumping).

for solar panels that are say 25% efficient, that means 75% of optical energy is turned into heat, whereas the sand had a relatively high albedo, its going to significantly heat up the local environment!

That is not what 25% efficiency means for solar panels.

I'm dumbfounded, most light incident on a solar panel is not reflected, so logically photons were absorbed, some generated useful electron hole pairs pushing current around the load loop, others recombined and produced heat. Its an entirely reasonable position in solar panel discussions to say that a 20% solar panel will heat as if 80% of the optical energy incident on the panel was turned into heat. Conservation of energy dictates that the input energy must equal the sum of the output work (useful energy) and output heat. Not sure what you are driving at here, and just calling a statement ridiculous does not explain your position.

You have not done any real world verification on any of this, you are arguing from a very flawed and overly simplistic lay-persons theoretical model of how solar panels must function in space and then you draw all kinds of conclusions from that model, none of which have been born out by experiment. 25% efficiency for a solar panel means that 25% of the sunlight incident on a panel was turned into electricity. It has nothing to do with how big a fraction is turned into heat, though obviously the more of it is turned into electricity the less there is available to be converted into heat. And it does not account for other parts of the spectrum that are outside of the range that the panel can capture. That 25% is peak efficiency. It does not take into account: (1) the temperature of the panel (higher temp->lower efficiency), hence the need for passive cooling of the panels in space due to a lack of working fluid (air). (2) the angle of the incidence: both angles have to be 'perfect' for that 25% to happen, which in practice puts all kinds of constraints on orientation, especially when coupled with requirements placed on the rest of the satellite. (3) the effects of aging (which can be considerable, especially in space), for instance, due to solar wind particles, thermal cycling and so on (4) the effect of defects in the panels causing local failure that can cascade across strings of cells and even strings of panels (5) the effects of the backing and the glass (6) in space: the damage over time due to mechanical effects of micro meteorite impact on cells and cover; these can affect the panels both mechanically and electrically To minimize all of these effects (which affect both operational life span of panels as well as momentary yield) and effectively to pretend they do not exist is proof that you are clueless, and yet you make these (loud) proclamations. Gell-Mann had something to say about this, so now your other contributions suffer from de-rating.

1) yes solar panels should be cooled, but this is feasible with thermal radiation (yes it takes surface area) 2) pointing the panels straight at the sun for a sun-synchronous orbit is not exactly unobtainium technology 3) through 6) agreed, these issues need to be taken into account but I don't see how that meaningfully invalidates my claim that a solar panel operated at 25% efficiency turns ballpark ~75% of incident photons into heat. Thats basic thermodynamics.

http://english.scio.gov.cn/m/chinavoices/2025-10/23/content_... In your opinion, how credible is this story?

OK I read the story (it was shorten than expected). So simplistically put there are 3 periods: 1) the grassy period before overgrazing, lot of wind 2) the overgrazed period, loss of moisture retained by plants and loss of root systems, lot of wind results in soil run-away erosion without sufficient root systems 3) the solar PV period: at higher heights still lots of wind, but the installation of the panels unexpectedly allowed the grass to regrow, because wind erosion is halted. The PV panels actually increase the local heating, but that doesn't need to directly equate to temperature: the wind just carried away the heat so it's someone else's problem :). Also the return of soil moisture thanks to the plants means a return of a sensible heat buffer, so the high temperature in the overgrazed period before solar panel introduction may not actually be an average temperature increase, but an increase in peak temperature during the summer. Imagine problematic summer temperatures, everybody would be talking about the increased temperature, when they are really just experiencing the loss of a heat buffer. At least thats my impression from the story.

Honestly, there's not a lot else I can think of if your goal is find some practical and profitable way to take advantage of relatively cheap access to near-Earth space. Communication is a big one, but Starlink is already doing that. One of the things space has going for it is abundant cheap energy in the form of solar power. What can you do with megawatts of power in space though? What would you do with it? People have thought about beaming it back to Earth, but you'd take a big efficiency hit. AI training needs lots of power, and it's not latency sensitive. That makes it a good candidate for space-based compute. I'm willing to believe it's the best low-hanging fruit at the moment. You don't need any major technological advances to build a proof-of-concept. Whether it's possible for this to work well enough that it's actually cheaper than an equivalent terrestrial datacenter now or in the near future is something I can't answer.

Building nuclear-powered and solar powered datacenters in places with low population density will still be cheaper. Do you think Mongolian government won't allow China to build datacenters if the price is right?

It might be easier in China but that doesn't help Elon or Americans. Solar powered datacenters on Earth don't make sense to me. The GPUs are so expensive you want to run them 24/7 and power cycling them stresses the components a lot so increases failure rate. Once it boots up you need to keep the datacenter powered, you can't shut it down at night. Maybe for CPU datacenters solar power can make sense sometimes, but not for AI at the moment. Nuclear is super hard and expensive to build. It probably really is easier to put servers in space than build nuclear.

Communication is a well-understood problem, and SpaceX already has Starlink. They might need pretty high bandwidth, but that's not necessarily much of a problem in space. Latency could be a problem, except that AI training isn't the sort of problem where you care about latency. I'd be curious where exactly they plan to put these datacenters... In low Earth orbit they would eventually reenter, which makes them a pollution source and you'd have no solar power half the time. Parking them at the Earth-Sun L1 point would be better for solar power, but it would be more expensive to get stuff there.

> you'd have no solar power half the time Polar orbit.

Seasons mess that up unless you're burning fuel to make minor plane changes every day. Otherwise you have an equinox where your plane faces the sun (equivalent to an equatorial orbit) and a solstice where your plane is parallel to the sun (the ideal case).

https://en.wikipedia.org/wiki/Sun-synchronous_orbit A Sun Synchronous orbit at the Day-Night terminator solves this issue

True. It would a tradeoff with the fuel consumed vs doubling power output.

Seems a bit of both. But no disparagement to your floor mopping (as I once was a dishwasher in a commercial kitchen myself), but there's a big gap between cleaning a floor, or a dish, and creating frontier models and spaceships. That said: I think solar is niche, and a moon-shot for how they want it. Nuclear is the future of reliable energy for human civilization. I think the K-scale is the wrong metric. I don't think we should be trying to take all the sun's energy as a goal (don't blot out the sun! don't hide it in a bushel!), or as a civilizational utiltiy - I'm sure better power supplies will come along.

The experiment may have been successful, but if it was why don't we see underwater datacenters everywhere? It probably is a similar reason why we won't see space datacenters in the near future either. Space has solar energy going for itself. With underwater you don't need to lug a 1420 ton rocket with a datacenter payload to space.

Salt water absolutely murders things, combined with constant movement almost anything will be torn apart in very little time. It's an extremely harsh environment compared to space, which is not anything. If you can get past the solar extremes without earths shield, it's almost perfect for computers. A vacuum, energy source available 24/7 at unlimited capacity, no dust, etc.

Power would almost certainly mostly come from solar panels. The SpaceX-xAI press release mentions using mass drivers which are electrically powered. Could make Hydrogen-Oxygen rocket fuel but not needed in Moon's lower gravity/thin atmosphere.

> We currently make around 1 TW of photovoltaic cells per year, globally. Doubling every three years; at that rate it would take about 30 years for 1TW to become 1000TW. Whether on not the trend continues largely depends on demand, but as of right now humanity seems to have an insatiable demand for power.

I think it largely depends on what bottlenecks exist that we haven’t hit yet.

We’re not going to use 100% of our solar panel manufacturing capacity to power space data centers, specifically because everyone else on the ground is so power-hungry. If we’re being generous, it could maybe top out at 1%, which adds another ~20 years to your timeline for a total of 50. I think it’s safe to say this part is bunk (along with everything else about this plan which is also bunk).

Space to put them, terrestrially, is not infinite. Demand has a hard ceiling.

Plenty of space still, but we're running into other scaling issues now - power grids are at their limits. And on sunny days there's a lot more supply than demand, but that can be mitigated by adding more (battery) storage.

That's a supply ceiling. Funnily, it's also one that's solved by putting them in space.

In fairness, solar cells can be about 5x more efficient in space (irradiance, uptime).

The quoted "1 TW of photovoltaic cells per year, globally" is the peak output, not the average output. They're only about 20% higher peak output in space… well, if you can keep them cool at least.

But there are no clouds in space and with the right orbit they are always facing the sun

You know how people sometimes dismiss PV by saying "what happens at night or in cloudy weather?"? Well, what happens over the course of a year of night and clouds is that 1 TW-peak becomes an average of about 110 to 160 GW. We're making ~1 TW-peak per year of PV right now.

but then you have answered the earlier question: solar panels in space pay themselves back ~7-8 times faster

That wasn't the original question. The head of this thread was quoting Musk's claim, which I repeat here: > it is possible to put 500 to 1000 TW/year of AI satellites into deep space This is 500-1000 times as much as current global production. Musk is talking about building on the Moon 500-1000 times as much factory capacity as currently exists in aggregate across all of Earth, and launching the products electromagnetically. Given how long PV modules last, that much per year is enough to keep all of Earth's land area paved with contiguous PV. PV doesn't last as long in space, but likewise the Moon would be totally tiled in PV (and much darker as a consequence) at this production rate. In fact, given it does tile the moon, I suspect Musk may have started from "tile moon with PV" and estimated the maximum productive output of that power supply being used to make more PV. I mean, don't get me wrong, in the *long term* I buy that. It's just that by "long term" I mean Musk's likely to have buried (given him, in a cryogenic tube) for decades by the time that happens. Even being optimistic, given the lack of literally any experience building a factory up there and how our lunar mining experience is little more than a dozen people and a handful of rovers picking up interesting looking rocks, versus given how much experience we need down here to get things right, even Musk's organisation skills and ability to enthuse people and raise capital has limits. But these are timescales where those skills don't last (even if he resolves his political toxicity that currently means the next Democrat administration will hate his guts and do what they can to remove most of his power), because he will have died of old age.

I wasn't referencing Elon's claim, but your reply to > In fairness, solar cells can be about 5x more efficient in space (irradiance, uptime). Clearly this person was referencing a financial efficiency predominantly through uptime. Your other points: I agree :)

> Clearly this person was referencing a financial efficiency predominantly through uptime. I read the person you are quoting differently, as them misunderstanding and thinking that the current 1 TW-peak/year manufacturing was 1 TW-after-capacity-factor-losses/year.

The 1TW is the rated peak power output. It's essentially the same in space. The thing that changes is the average fraction of this sustained over time (due to day/night/seasons/atmosphere, or the lack of all of the above). It's still the same 1TW theoretical peak in space, it's just that you can actually use close to that full capacity all the time, whereas on earth you'd need to over-provision substantially and add storage, so 1TW of panels can only drive perhaps a few hundred GW of average load.

> the whole capacity Wouldn’t something like half of the panels be in shadow at any time?

Depends where you put them. The current vogue option is a sun-synchronous orbit: https://en.wikipedia.org/wiki/Sun-synchronous_orbit

polar orbit

It is more than 5x less expensive to get surface area on earth’s surface.

The dominant factor is "balance of system" aka soft costs, which are well over 50%.[0] Orbit gets you the advantage of 1/5th the PV and no large daily smoothing battery, but also no on-site installation cost, no grid interconnect fees, no custom engineering drawings, no environmental permitting fees, no grid of concrete footers, no heavy steel frames to resist wind and snow loads. The "on-site installation" is just the panels unfolding, and during launch they're compact so the support structure can be relatively lightweight. When you cost building the datacenter alone, it's cheaper on earth. When you cost building the solar + batteries + datacenter, it (can be) cheaper in space, if you build it right and have cheap orbital launch. [0] https://en.wikipedia.org/wiki/Balance_of_system

Funny, I would have included transportation as part of the installation cost. You didn't mention that one.

I do say it's predicated on cheap orbital launch. Clearly they expect Starship to deliver, and they're "skating to where the puck will be" on overall system cost per unit of compute. But yeah, I didn't include that delivering all that stuff by truck (including all the personnel) to a terrestrial PV site isn't free either.

Yeah, soft costs like permitting and inspections are supposedly the main reason US residential solar costs $3/watt while Australian residential solar costs $1/watt. It was definitely the worst and least efficient part of our solar install, everything else was pretty straightforward. Also, running a pretty sizable array at our house, the seasonal variation is huge, and seasonal battery storage isn’t really a thing. Besides making PV much more consistent, the main thing this seems to avoid is just the red tape around developing at huge scale, and basically being totally sovereign, which seems like it might be more important as tensions around this stuff ramp up. There’s clearly a backlash brewing against terrestrial data centers driving up utility bills, at least on the East Coast of the US. The more I think about it, the more this seems like maybe not a terrible idea.

So far most of the datacenters are built in very convenient places and people will start to build them in inconvenient places like Sahara or Mongolia way before they will building them in space

Right now it is. However, the amount of available land is fixed and the demand for its use is growing. Solar isn't the only buyer in this real estate market.

We have so much excess land with no real use for it that our government actually pays farmers to grow corn on it to burn in cars. Availability of land for solar production isn't remotely a real problem in the near term.

This is really underselling it tbh. Any land that's growing corn in a developed country is likely top 1% of land on earth. Half of the earth is desert and tundra. Which is still incredibly easier to work with than space because you can ship there with a pickup very cheaply. Maybe when nevada and central australia are wall-to-wall solar panels we can check back on space.

The Technology Connections Youtube channel recently did a great video arguing pretty convincingly that the land used to grow corn for cars would be vastly more efficiently used from an energy perspective if we covered it with solar panels.

Realizing the impracticality of it (and that such approaches often collapse under the infeasibility of it) ... wouldn't it be better to... say... cover the Sahara in solar panels instead? That's gotta be cheaper than shipping them into space. https://inhabitat.com/worlds-largest-solar-project-sahara-de... https://www.theguardian.com/business/2009/nov/01/solar-power... (and a retrospective from 2023 - https://www.ecomena.org/desertec/ )

From an engineering perspective, with today’s costs, yes. But don’t forget the political complications of dealing with all those countries that own the Sahara, that’s going to come at it’s own cost.

Solar can always just go on the roof...

Fortunately there are no downsides to launching solar cells into space that would offset those gains.

Solar cells have exactly the same power rating on earth as in space surely? What would change is their capacity factor and so energy generation.

Solar modules you can buy for your house usually have quoted power ratings at "max STC" or Standard Testing Conditions, which are based on insolation on Earth's surface. https://wiki.pvmet.org/index.php?title=Standard_Test_Conditi... So, a "400W panel" is rated to produce 400W at standard testing conditions. I'm not sure how relevant that is to the numbers being thrown around in this thread, but thought I'd provide context.

That's super interesting. STC uses an irradiance of irradiance 1000W/m2, in space it seems like you get closer to 1400W/m2. That's definitely better, but also not enormously better. Seems also like they are rated at 25C, I am certainly not a space engineer but that seems kind of temperate for space where cooling is more of a challenge. Seems like it might balance out to more like 1.1x to 1.3x more power in space?

The atmosphere is in the way, and they get pretty dirty on earth. Also it doesn't rain or get cloudy in space

Sure but like, just use even more solar panels? You can probably buy a lot of them for the cost of a satellite.

The cost of putting them up there is a lot more than the cost of the cells

>just use even more solar panels I think it's because at this scale a significant limit becomes the global production capacity for solar cells, and SpaceX is in the business of cheaper satellites and launch.

You don't even need a particularly large scale, it's efficient resource utilization. Humanity has a finite (and too small) capacity for building solar panels. AI requires lots of power already. So the question is, do you want AI to consume X (where X is a pretty big chunk of the pie), or five times X , from that total supply? Using less PV is great, but only if the total cost ends up cheaper than installing 5X the capacity as terrestrial PV farms, along with daily smoothing batteries. SpaceX is only skating to where they predict the cost puck will be.

And in geostationary, the planet hardly ever gets in the way. They get full sun 99.5% of the year.

That's still a smaller ratio than the ~4X gain in irradiance over LEO. But if you're doing it at scale you could use orbital tugs with ion drives or something, and use much less fuel per transfer. It's probably not competitive at all without having fully reusable launch rockets, so the cost to LEO is a lot lower.

even at 10% (say putting it on some northen pile of snow) it is still cheaper to put it on earth than launch it

Satellites can adjust attitude so that the panels are always normal to the incident rays for maximum energy capture. And no weather/dust. You also don't usually use the same exact kind of panels as terrestrial solar farms. Since you are going to space, you spend the extra money to get the highest possible efficiency in terms of W/kg. Terrestrial usually optimizes for W/$ nameplate capacity LCOE, which also includes installation and other costs.

Atmospheric derating brings insolation from about 1.367KW/m2 to about 1.0. And then there’s that pesky night time and those annoying seasons. It’s still not even remotely reasonable, but it’s definitely much higher in space.

> And then there’s that pesky night time and those annoying seasons. The two options there are cluttering up the dawn dusk polar orbit more or going to high earth orbit so that you stay out of the shadow of the earth... and geostationary orbits are also in rather high demand.

Put them super super far away and focus all the energy into one very narrow death laser that we trust the tech company to be careful with.

That's not what I'm suggesting. The post says "deep space". If you're going to try to harvest even a tiny percentage of the sun's energy, you're not doing that in Earth's orbit. The comparison is a webcam feed from Mars.

> it is possible to put 500 to 1000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the Sun’s power Which satellites are operating from "deep space"?

> We currently make around 1 TW of photovoltaic cells per year, globally. China made 1.8 TW of solar cells in 2025. The raw materials required to make these are incredibly abundant, we make as much as we need.

You missed the point. We can make ten or hundred times the number of solar cells we make right now, we just don't have a reason to. The technology is fairly ancient unless you want to compete on efficiency, and the raw materials abundant.

I agree that part of the bottleneck is deploying solar physically. China is the best in the world in deploying solar panels. They are only managing linear increases in their solar capacity, year over year.

Whilst I agree that this glosses over a huge number of technical obstacles, space based solar power could scale more easily than that on earth. Lack of variable weather and gravity means rather than using photovoltaic cells, you can just set up paper thin huge mirrors to focus light and generate steam. Caveat: my understanding of this largely comes from the book The High Frontier, which is really old and probably inaccurate. I can't think of a reason why this particular point would be wrong though.

> What do you think the limiting factor is? I don't see why we can't scale manufacturing of satellites up as far as we want. A reason. I'm sure that theoretically it's possible, assuming infinite money and an interest to do so. But literally, why would we? There's no practical ways to get the power back on earth, it's cheaper to build a solar field, etc. And I don't believe datacenters in space are viable, cost wise. Not until we can no longer fit them on earth, AND demand is still increasing.

The inner planets contain enough mass to create a shell of 1 AU radius with mass of 42 kg/m^2. That sounds like a plausible thickness and density for a sandwich of photovoltaics - GPUs - heat sinks. You don't build a rigid shell of course, you build a swarm of free-floating satellites in a range of orbits. See https://www.aleph.se/Nada/dysonFAQ.html#ENOUGH for numbers.

The burned propellant and oxygen mass (as H2O and CO2) almost all ends up back in the atmosphere when you launch to LEO, so you can keep running electrolysis (powered by solar) to convert it back to fuel.

You're not considering some important multipliers. In space you're already getting a substantial immediate boost due to greater solar irradiance - no atmosphere or anything getting in the way of those juicy photons. You can also get 24 hour coverage in space. And finally they mention "deep space" - it's unclear what that means but solar irradiance increases on an inverse square law - get half way to the sun and you're getting another 4x boost in power. I'm sure there's other factors I'm not considering as well - space and solar just go quite well together.

Help me understand something. We make 1 TW of cells per year but we're struggling with bringing 1 GW consuming data centers online?

Nameplate capacity needs a derate for availability, so you can drop it down to about 200GW(e) equivalent continuous power assuming we're making and deploying enough batteries to support it. More, obviously, if those panels are going to an equatorial desert, less if they're going to sunny Svalbard in the winter time.

Photovoltaic production has been doubling every year. That's not a huge amount of doubling!

And is that "Minor" ? Is that actually practical on a reasonable budget? Aren't there better uses for the solar panels etc?

> Figuring out how to radiate a lot of waste heat into a vacuum is fighting physics. Radiators should work pretty well, and large solar panels can do double duty as radiators. Also, curiously, newer GPUs are developed to require significantly less cooling than previous generations. Perhaps not so coincidentally?

Well there lies the rub, solar panels already need their own thermal radiators when used in space ...