wrote
Rod Speed wrote

But it will work fine with clothes drying, dishwashing etc
where its fine to do it at the cheapest rate in the middle
of the night. Same with water heating and heatbanks
and would allow charging at the higher cost when you
run out of hot water etc without needing to duplicate
the heating elements as you do currently.

That's how the systems that already have smart meters do it.

How?

By having the smart meter keep track of the time of day the
power is used so the supply operation can charge less for
the electricity used in the middle of the night than it does
for electricity which is used at peak demand times when it
cost the supply operation more for that electricity.

Usually called a time of use tariff.

I already run my dishwasher, tumble drier and washing machine
in the small hours. How will a smart meter help me do that?

By keeping track of when you use that electricity.

Why can't the supplier simply tell me (or the appliance)
directly over the internet?

Because the appliances aren't listening to the internet.

How does a smart meter help?

See above.

https://en.wikipedia.org/wiki/Time-based_pricing