The UK is currently experiencing some prolonged windy weather and my all-renewable energy provider offers dynamic pricing. That means cheap energy and even negative-cost energy. This is where my HA instance shines and saves me a fortune on my power bill. Thanks again to the HA devs for this incredible project.
For the curious, I'm using bottlecapdave's excellent Home Assistant Octopus Energy integration via HACS.
Whole-home metering is done with a Home Mini, a device that Octupus gives away to any customer that asks nicely and provides real-time data. For devices with plugs is mostly LocalBytes smartplugs or similar. For the heaters, well, hypothetically, that would require installing something like a Shelly PM Mini Gen 3 inside the wall box behind the heater without asking the landlord's permission.