Some of them (most of the latest models) are scriptable on-device. There are some ready-made scripts for the Nordics that check the current electricity prices

Some of them (most of the latest models) are scriptable on-device. There are some ready-made scripts for the Nordics that check the current electricity prices and use those with some basic rulesets to see if the electric heating in a house should be on or off for example. I just use mine to turn off the ice machine at 22:00 so it doesn't run through the night :D