Pre-war from what I understand we had duel tariffs, one for lighting and one for power, and it was illegal to run the smoothing iron from the lights. The government wanted to encourage people to light their homes with electric, as so many house fires caused by candles, oil lamps and gas lamps. With duel supplies it would be possible to have lights and freezers on an uninterrupted supply, and other thinks on a supply which the supplier could switch off, this is already happening to an extent with EV charge points which the supplier can turn off when there is a problem with the supply.
But clearly the consumer unit will need designing to use a duel supply, the one point isolator will need to have more that two poles, and in real terms the whole house will need to be wired to allow for the duel supply.
So in real terms two high usage devices are likely to have DNO switching, the heating, and the EV charging, this will allow load shedding while extra generators are put on line.
So in real terms the smart meter is useless, we know how much items use, it's written on them, there are exceptions like the washing machine, however I have tried using an energy monitor on the washing machine, and using the same cycle each time, the energy used to complete a wash varies, even more so with a washer/drier as the machine varies the water used, and cycle times depending on the weight of the load and humidity of drying air. So even if you know what has been used each wash, there is little you can do.
I use energy meters on my smart chargers, so from my PC I can see when the charge is complete, also when brewing beer, if the heater has switched on every so often I know brew was cool enough, even used a combined monitor and wifi switch to turn on my air conditioning unit, I can see remotely if cooling has switched on, showing room was too warm, if only fan turns on then room cool enough.
But all this needs individually measurement, one could I am sure fit a unit on the lights to see if any left on, but the big question is with LED lights is it worth it. Outside light uses 15 watt, I paid £8 for a device to switch it on at set times, and allow me to set those times on the phone, but a second light charged by sun light, with a PIR also lights route to back door, so in the main that light off the wifi switch is redundant. So we have less and less devices that we can leave on, and even if left on, does 15 watt matter.
So grouping all power together, I can see no point in taking a reading, I have a clamp-on current transformer, and a remote meter to show total usage, total waste of time and batteries to run it, yes we see it jump up when the kettle is put on, but the kettle only boils a cup at a time, so knowing how much it uses can't save power.
As there are today there is no real point in the smart meter, that clamp-on current transformer came from Scottish power, and was used to work out my bills, and the bills when corrected one a year were never more than £5 out, and no need for me to read meter, there is simply no need for a smart meter unless you have micro generation, the only thing the smart meter can do which the old meter did not is work out the direction the power is flowing. OK it has a built in isolator, which the supply companies say they will not use, the only advantage is if it could be used in the event of fire, or request from owner.
So if while on holiday you see home using 3 kW and you realise there is a room heater or immersion heater left on, you could switch off power remotely, in fact it would be handy to be able to turn off immersion heater remotely, although it would also turn off freezer, so of limited use. But your not given access to the remote control isolator so it is of no benefit.
