Why isn’t this as easy as storing some of that excess energy in a home battery and letting the rest down in a wire into the ground? Then if it’s smart enough it could only give back energy when needed.
Well, that’s what they’re doing some places. The batteries assets are not in private homes usually though, they’re by themself or run by power-consuming industries. Batteries are expensive though, and they degrade quickly if you use them wrong. In the EU, ENTSO-E defines the market rules, trade systems and messaging systems that energy companies and asset owners play by. Sometimes the revenue-generating asset is a battery, sometimes it’s a hot water boiler, wind park, factory, hydro plant etc.
While water in pipes is often a metaphor for electricity, it’s not particularly useful here. You can’t ground out part of a charge. Energy storage is the solution though. Batteries are good, pumping water up back up into dams to be regained from a hydro plant when needed is ideal, as I understand it.
The easiest solution is to send the power somewhere else where it can offset the use of fossil fuels. This solution is fraught with political hurdles, subject to market forces (due to privatization) and often grid compatability issues(looking at you Texas). It is, however, a time tested and common method for mitigating excess production.