This is a highly interesting idea. I wonder how much they will cost? I'm sure if even one person did a "ready-reckoner" on how much it could save people, they would sell like hot cakes. Even if it takes 5 years to pay for itself. We both work at home and have a house-bound adult kid, so something is always being used during the day i.e. 3 monitors, PC, laptop, gaming PC, TVs, kettle, washing machine, air fryer, hob....Not to mention the things that are always on like Wifi router, TVs on standby. It's also a good way to help out with the environment? With my tin hat on, I wonder if the energycartelscompanies will try to say they don't work, or they "aren't compatible with your meter, and using equipment like this will incur a 15% increase on your bill for the additional strain on the system"?
The article said payback could be as quick as 4 years.