uhubctl's home page has a list of supported hubs. Apparently Amazon's house brand usb hub ("Amazonbasics") currently supports it, so it seems currently easy to find one.
I happened to have earlier purchased an industrial quality hub that's powered by 12-24V DC, and it turned out to have per-port power control.
Power factor is another concern BTW; I was measuring something like 0.15 power factor when the drive was powered down, and I'm unclear how such a low PF affects inverter efficiency (it probably depends on how good the inverter is). Powering the drives from 12V DC would probably improve their offgrid efficiency.
I happened to have earlier purchased an industrial quality hub that's powered by 12-24V DC, and it turned out to have per-port power control.
Power factor is another concern BTW; I was measuring something like 0.15 power factor when the drive was powered down, and I'm unclear how such a low PF affects inverter efficiency (it probably depends on how good the inverter is). Powering the drives from 12V DC would probably improve their offgrid efficiency.