> Turn off solar+wind remotely (often very expensive to retrofit to existing installations as the Germans found out)
If we're talking about problems that show up when wind/solar becomes an order of magnitude more prevalent than it is now, why would you care about the cost of retrofitting anything?
I would assume that all-DC grid would happen before that (and solve the issues with grid stability). Extrapolating from the rate at which Europe migrated from 110V AC to 230V AC you are looking at at least 50 years for that to happen.
Yes but little to no new stuff is getting fitted with this when installed outside of Germany. It significantly puts the price of installs up. You have to dump the power somewhere and it's not cheap/easy to.
If we're talking about problems that show up when wind/solar becomes an order of magnitude more prevalent than it is now, why would you care about the cost of retrofitting anything?