[LeoPanthera]

You are going to be utterly shocked when you realize that solar panels work on the ground, too. You can buy so many batteries, and so many geographically separated locations for your panels, for the price of launching a datacenter into space.

[pgt]

Batteries are expensive.

Marginal cost of launches keep coming down for SpaceX with reusable rockets and lifetime of satellites is long.

[pgt]

Solar panels are much more efficient in space (no atmosphere).

Before downvoting, would you mind quoting the relative cost of batteries vs. solar panels for a 150kW solar-powered satellite?

[LeoPanthera]

> would you mind quoting the relative cost of batteries vs. solar panels for a 150kW solar-powered satellite

OK.

At a good location (~25% capacity factor), you need about 600 kW of panels to average 150 kW. Utility-scale solar runs roughly $0.50–$1.00/W installed, so call it ~$450K–$600K. Overnight storage (say ~16 hours) requires ~2,400 kWh. Adding a buffer for cloudy days, say 4,000–7,000 kWh total. At roughly $200–$350/kWh (utility-scale Li-ion), that's ~$1M–$2M.

In a favorable orbit, capacity factor is ~90–100% (GEO or sun-synchronous), so you need roughly 160–170 kW of panels. Space-qualified solar panels historically cost $100–$300/W. Even optimistically at $50–$100/W with newer manufacturing, that's 167 kW * $100/W = ~$17M optimistically, or 167 kW * $200/W = ~$33M realistically. You also need space-rated power management, thermal systems, and radiation-hardened electronics.

Even ignoring launch costs entirely, space solar is roughly 10–20x more expensive than ground solar + batteries, driven almost entirely by the enormous cost premium of space-qualified solar panels. Ground-based solar is extraordinarily cheap now (~$0.50–1/W), while space-grade panels remain orders of magnitude more expensive per watt.

The ground option wins overwhelmingly. The space option would only start to make sense if space-grade panel costs dropped to near terrestrial levels, which would require a revolution in space manufacturing.

[AlexandrB]

150kW solar kit seems to cost around $150k[1]. With the cost of launch with Falcon Heavy, this would pay for about 100kg of payload[2]. Each Starlink satellite weighs ~300kg[3] so I suspect a 150kW "datacenter" satellite would weight much more. Where are the savings supposed to come from? Seems like you could overprovision terrestrial solar panels by 3-4x and still obviously come out ahead. And that's all before considering the R&D costs of building AI datacenter hardware that can survive the orbital radiation environment.

[1] https://sunwatts.com/150-kw-solar-kits/

[2] https://ourworldindata.org/grapher/cost-space-launches-low-e...

[3] https://everydayastronaut.com/starlink-group-4-5-falcon-9-bl...

[lm28469]

> so I suspect a 150kW "datacenter" satellite would weight much more.

150kw is just enough to power a single gb300 rack, the rack alone weights 1500kg+

[lm28469]

They lose 0.5% efficiency for every 1c above 25c, do you plan on having your space panels actively cooled?

FYI you'd need 2x the solar panels of the ISS to run a single rack of NVIDIA GB300, and microsoft just built a datacenter with 4600 of these racks.

[philistine]

Never forget cooling. People imagine a square box with a ginormous sea of solar panels attached, and forget the atrocious and horrible cooling required to vent all the heat that makes your home sewage line look like bottled water by comparison.

[notrealyme123]

With or without the rocket?