I don't know. I don't have control over a lot of things. A fridge, for instance: I was limited by what could fit up the stairs and in the door of my apartment. (It is small, but not too tiny). Showers, and therefor hot water, is generally done around schedules. I hand dry all of my clothes, but the shared washer is in the basement - I can't leave clothes in all night. Folks with children often must do lots of laundry when they have time - and not to mention that leaving clothes in the washer at night in hot weather can sometimes create stink. Eating, again, depends on schedule. I need heat when I need heat, not when it is convenient for the electricity. I'm not in a minority with this stuff and so many people have fewer choices than I do - and usually, the poorer folks who need it the most are the ones without as much control. And can't stay home to work around these things.

Hot water storage is very cheap. Water has tremendous heat capacity.

So that's a great example about what can be scheduled in a flexible way.

If something is not standard practice doesn't mean it can't be done, or even that it's hard to do. There was no motivation to use any smarts for water heaters because the electricity price was flat, or the price was on a fixed schedule (timers and night heating of water, was done in the eighties here already).

It doesn't matter how much it costs to store water. It costs money to heat the water, and that's what you have to pay attention to. This is much harder to work around as you don't have much choice when you use a hot water. Hot waters don't just store cold water in the tank to be heated when electricity prices are low. Instead, it'll start heating after you shower, for example.

I am in an apartment: I have a small water heater - I easily run out of water taking a shower if I stick around too long. There are two people in the house, and if we both want to shower in one day, the hot water . That way, I have hot water to do dishes and someone can take a shower in evening. I'm happy the water heater for the washer is separate, but again, it heats when the temperature dips and doesn't keep the water cold until electricity is cheap.

Even if the hot water heater waited to heat until prices were low, you are going to have water that is not-as-hot if you are the second person taking a shower. This is simply because as the tank empties, cold water is added to the tank. All subsequent hot water will be cooler.

I'll add that some folks sweat at night and must take a shower in the morning (I do when hormones act up. Night sweats are no joke).

I'm in an apartment: I cannot update the hot water heater. It literally cannot be done for me and millions of others because we cannot replace such things. You'd have to mandate landlords do improvements, and even then, it'll be years before it is all upgraded.

I'd argue that the real answer is to go with tankless heaters in this case: It isn't that you'll be spending money when the electricity is cheap, but you'd use less overall for the actual heating of water.

Way back when we had immersion water heater with a big insulated tank in a cupboard in the house (a was common in UK then) we'd switch the heater on when we needed it. An hour before having a bath say.

Where has is available most people have Combi boilers in the UK, very little or no storage, instant hot water in demand.

The idea would be that you notice the electric price is negative (or a control system 'notices' for you) and turn your immersion heater on. The water retains enough heat you have plenty of time to use that water.

If we have excess solar this is an inefficient but easy way to slurp it up. Hydroelectric pumped storage would probably be better but grid capacity for that seems low.

These are technologically simple problems.

The solutions are simple, but the implementation is not. A lot of places don't have room for a water heater to store a larger amount of hotter water in order to load shift. furthermore, it's not guaranteed that electricity prices will cause any savings or provide a similar reliability of hot water.

And not every place has to do it. Most houses have plenty of room for bigger and more complex water heaters. Many of those apartment complexes that use centralized ones have room as well.

The whole thread was started on the premise that "hot water is an especially hard problem for load shifting, because people have to get hot water immediately" - while the case is the opposite - because hot water is very easy to store.

This has been/is implemented in various parts of the US, but deregulation can go bothways and consumers aren't always happy. When a winter cold snap hits the northeast and energy demand goes up, the market responds as expected. Of course a rational response would be to also consider the savings during other parts of the year, but large seasonal fluctuations in the utility bill does not agree with many consumer's psychology and budgeting habits.

https://www.virginiamercury.com/2020/03/17/va-to-try-limited...

https://www.opensecrets.org/news/issues/electricity/

I think the answer to that is capping consumer price to encourage suppliers to handle variation?

Although, in general if it encourages super-insulation of homes and things like ground-source heating ...?

The Tesla Powerwall enables the uncoupling of rates and usage, but I'm not sure how long it takes for a return of investment.

When I did the math for our house, despite a 13yen difference between night and day, the power wall never made recoup. The biggest issue is battery's limited life cycle and overall high cost.

The math worked out to 30 years before raw recoup. Once you add in a discount rate or life cycle would never justify itself. The per watt hour cost installed keeps to come down massively.

I imagine that in a world where a substantial proportion of energy came from solar, the night-day difference would be much more pronounced, and the economics would shift.

I am currently working on something that is trying to solve this by more accurately pricing DERs https://www.greentechmedia.com/articles/read/opus-one-tests-...

Move to California, which has very high electric prices and time-of-use variations are extreme.

Solar and batteries are economical.

One house can be run on just 1 or 2 EV battery and 5KVA inverter for most houses.

Once EV batteries become cheap, I'll charge my batteries when grid price is low.

Fridges are a huge opportunity - they could easily monitor the frequency of the mains supply and turn the pump off whenever load drops under 50hz.

Users would never even know, if they were factory wired with this kit the lights and any gadgets could continue to work.

Perhaps this should be something manufacturers have to include in order to get their A+++ energy rating.

There are lots of interesting things like this right now. For instance, there is work on hot water heaters that can store excess energy by heating water hotter when electricity is cheap and then mixing with cold water to maintain a constant temp throughout the day / night.

See also "smart grid" ( https://fr.wikipedia.org/wiki/Smart_grid ) and "vehicle to grid" ( https://en.wikipedia.org/wiki/Vehicle-to-grid )

Using the grid frequency as a price signal seems to make perfect sense. A mapping table can be published of frequency to market price, and updated periodically. The prices for outer extremes of allowable system frequency should be "+Infinity" and "-Infinity" so there is never a situation that someone let's the grid frequency go outside allowable bounds for business reasons.

Then home users can use devices with very basic built in electronics to save money or even earn money on electricity bills.

It makes sense as a concept. In practice, it may lead to very unfortunate feedback effects if deployed at scale.

Use low-precision frequency references, then. At scale it'll smear out the demand spike.

Except it's negative feedback... Which increases system stability.

You still need to centralize this though.