> 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.