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.
Maybe evcc is helpful for you. It can control EV charging stations and batteries based on fine granular rules: https://evcc.io/