Comment by somewhereoutth

So apparently grid forming or synthetic inertia can be provided electronically nowadays, but presumably it would not be too terrible to put a rotating mass in between the (e.g.) solar power source and the rest of the grid? So the electricity from the solar panels runs a motor that turns a generator. I suppose power is lost through friction and other inefficiencies, and you'd need to co-locate the solar panels into a big enough farm.