alt Hacker NewsSolar 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?
Replies
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.
With or without the rocket?
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...
> 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.