To add, so called 'dynamic energy contracts' are getting more and more popular, at least in my native Netherlands. The European day-ahead electricity market switched to 15-minute price blocks this month, to more accurately follow the supply and demand.

The market for power imbalance was already on 15 minute blocks.

I'm using a HomeWizard smart plug [0] to enable my electric boiler to only run during the cheapest hours of the day

[0] https://www.homewizard.com/energy-socket/