They don't need super heavy payloads, it seems pretty clear that they'll be able to launch even just a Falcon 9 payload in this for less than Falcon 9, because they're not throwing away the expensive upper stage.
Also, my understanding is that Starlink v3 just doesn't fit inside F9. The larger phased arrays that that enables lets them make much better use of spectrum than the v2 minis. There are lots of potential uses for larger payload volumes.
The space DC thing has been beaten to death online, with tons of very confident commentators claiming it will never happen for the reasons you've mentioned. Some counterpoints, Google just launched their first ML infra to space with their Project Suncatcher launch, and if you actually run the numbers, the radiators are smaller than the solar arrays, so obviously it's feasible to launch the radiator if it's feasible to launch the solar array to power it. Who knows if it'll make economic sense, but it seems pretty clear that it's getting harder to build DCs on the ground in the US, there's a lot of backlash against it, we just saw what it did to Abbott. Many areas don't have the spare power, and doing it in space makes solar into reliable baseload power rather than 1/8th nameplate and intermittent.
Anyway, I don't work in that industry, I've just been following along with them because I've been an investor since before Starlink was a thing, but I really think people should keep an open mind about whether SpaceX can pull off things that sound a bit nutty.
I don't know why people go on about the radiator, it's pretty obvious to me that the biggest challenge is your solar panels and radiators acting as wind sails that increase atmospheric drag. This is a manageable problem at small scales but it limits the maximum node size.
Also, my understanding is that Starlink v3 just doesn't fit inside F9. The larger phased arrays that that enables lets them make much better use of spectrum than the v2 minis. There are lots of potential uses for larger payload volumes.
The space DC thing has been beaten to death online, with tons of very confident commentators claiming it will never happen for the reasons you've mentioned. Some counterpoints, Google just launched their first ML infra to space with their Project Suncatcher launch, and if you actually run the numbers, the radiators are smaller than the solar arrays, so obviously it's feasible to launch the radiator if it's feasible to launch the solar array to power it. Who knows if it'll make economic sense, but it seems pretty clear that it's getting harder to build DCs on the ground in the US, there's a lot of backlash against it, we just saw what it did to Abbott. Many areas don't have the spare power, and doing it in space makes solar into reliable baseload power rather than 1/8th nameplate and intermittent.
Anyway, I don't work in that industry, I've just been following along with them because I've been an investor since before Starlink was a thing, but I really think people should keep an open mind about whether SpaceX can pull off things that sound a bit nutty.