However, wouldn't it make sense to e.g. adjust heating/air conditioning depending on electricity spot price? That's then just a gadget that gets the information and guides the home system.
It'll probably be more meaningful in some industrial plants though, if there's any such energy-intensive industry.
I'd be pretty happy to pause an EV charge many times. Since Teslas are data-connected, they could possibly do this with no grid interface beyond the power connection.
This is one very nice aspect of a grid when there are a lot of electric cars which charge at night, and have big enough batteries that they don't need to fully charge: you can absorb a lot of variability of overnight wind energy.
And if electric cars also plug in at work... jackpot.
Even better than that, it could be set up so that your house drew power from the car battery when rates were high! You could set it to, for example, draw from the car battery until the charge drops to 80% or some settable limit.
Then all the rechargeable cars become part of the battery moderation of the whole grid!
The Tesla engineering head said giving power back isn't likely, as it would degrade the battery too much, but he stressed how much benefit to grid stability could be delivered just by altering when the batteries drew power to charge.
Sure, there are some research projects for that, but note the wildly different cost: charging a little different doesn't degrade the car's battery. All it takes is an Internet connection, a good prediction of how much charge the driver will need, and a micropayment of some kind.
That's a no-brainer compared to paying the owner for shortening the life of the battery.
It'll probably be more meaningful in some industrial plants though, if there's any such energy-intensive industry.