We're already incentivized to do things like running the dishwasher in the evening do to costs, no? Or is the implication that it would be considerably even more cheap?
I've already switched hot water and pool pump to daytime rather than night. The dishwasher now runs in the morning, not after dinner. Washing and drying, Aircon/ heating mostly happened during the day anyway.
Overall our use of grid power has dropped to 20%, and I think we can get it down to 10% (at least I summer time.)
So yes, in the sense that the daytime cost is now a -lot- cheaper (think free) I'm seeing how we are heavily incentivised to change our usage patterns.
It doesn't really matter when I run these appliances. Between fixed rate electricity and net metering, the cost will be the same even if they run at night. But I get weird satisfaction knowing that the sun is providing the power.
In 2023 near half of my (relatively well insulated all electric home) energy use was charging my EV at home.
Edit: Any chance you're in the US? If so, what EV are you driving?
One thing that stood out to me is that in the case of thermal loads (perhaps your dishwasher but more realistically a hotwater heater). It will become more worthwhile for that system to know when high and low electricity prices are and store more heat (i.e. hotwater) at low electricity prices and wait until prices fall again to refill it. In this sense, a heater would be operating like a battery.
In a world where energy prices are stable throughout the day, it doesn't make sense to manufacture, for example, a price aware water heater with extra storage capacity. It seems like that calculus is changing with solar and other renewables creating an incentive for variable rates compared to traditional fixed rate alternatives.
In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Battery - are extremely flexible.
But we're still lacking good standards for reliable control. Today we do stuff like tell your HVAC to stop via vendor X's cloud API. What happens if your router dies after we send a "stop" command in the middle of the winter?
For many of the minisplits I see control code for, they'd just let the house freeze, waiting forever for another command that'll never arrive.
For critical functions like "keep my water pipes from freezing" / "be able to drive to work in the morning", we need much better standards for reliable control and safe failure modes.
If your IoT dies, you'll most likely get to the comfort mode.
Only nit is that in 2023 the default mode would probably be "eco" rather than "comfort"
My biggest issue in making this work reliably is that my "smart" thermostat is trying to be too smart.
Our power gets cheap at 10pm. I can't just set my HVAC to turn on at 10 and go full blast until power gets expensive again at 6am. I have to program a set temperature at a time. if I set that at 10pm, my thermostat tries to make sure that it _reaches_ that temp at exactly the time. So it will actually turn on an hour early. So I have to guess how long it will take my HVAC system to reach whatever temperature I have it set to, and then set it for that much time _after_ 10PM. It's inexact and annoying, and means that I am leaving performance on the table.
I have idly searched a few times for a replacement thermostat that would interact locally with home assistant and have had zero luck (partially due to the fact that my system is complicated and seems to have a non-standard wiring setup).
Everything else: hot water heater, EV, laundry, etc. are all trivially easy to make run during the desired periods. But the biggest use of energy I have (yes, larger than charging the car) is a PITA to make it play well with TOU billing.
The ‘smart’ thermostat can call for heat all it wants, but nothing will happen if the time switch relay contacts are open.
I’ve seen 50 year old 24 hour mechanical time switches operating just fine, and you won’t need to replace your thermostat.
This one is $122 and comes inside a NEMA 1 enclosure:
https://www.intermatic.com/Product/T104?setcontextlanguageco...
The dominant energy load in existing houses is heating. EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid. House Battery isn't a load, it's the expensive thing you suffer when the actual loads are inflexible.
Heating is slightly flexible, you can lower your thermostat at night, but it's also colder at night. And most existing heating is fossil fuels. Converting that to electricity is going to require more electricity consumption at night than we have now.
All the more important to ensure this additional demand is flexible. Shaping it to match renewable production and low-usage hours in the distribution grid means higher capacity factors across the board and less new transmission+distribution need.
> Converting <home heating> to electricity is going to require more electricity
Yes.
It's inherently flexible. Shaping it to be that way isn't a particularly hard problem. The issue is that it's entirely new demand -- what you're really replacing is the petroleum burned in existing cars, not any part of the existing power grid. So how do you solve the demand currently served by coal and natural gas and home heating oil, rather than gasoline and diesel?
> Converting <home heating> to electricity is going to require more electricity
I feel like editing out the "at night" part hasn't actually provided a mechanism for supplying that electricity at night when it's cold and you need heat.
I the more long term, exchanging resistive water heaters with heat pumps is the way to go (and already done throughout Scandinavia)
The good thing with both approaches is you don't need the appliance built to support it. For HVAC, the control system is in the thermostat, which is cheap and has a standard interface.
For waterheaters, you can just stick a relay in sequence with the heater.
Not where I live. Electricity costs the same here no matter what day or time of day it is.
Even apartments where hvac, hot water and laundry are central, and the builder/owner chooses the big appliances.
But it turns out people don’t care and didn’t bother with enough load shifting to cover the cost.
“Smart Metering Costs to Date Exceed Projected Costs and Benefits” says it all.
They did get/build a $249m centre to monitor all the data though.
https://www.auditor.on.ca/en/content/annualreports/arreports...
Even after ~15 years, most equipment still doesn’t care about time of use.
Most savings have been due to better regulations/promotions around efficiency. Subsidized LED light bulbs accomplish more than telling people to turn off the incandescent.
But you know, giving useful stuff to people for free is WeLFarE but forcing untested policies on them and making them pay for it is okay.
It depends very much on the weather, but in Denmark the cost can vary from around 1DKK/kWh (€0.14) to 5kr/kWh (€0.67), or a few hours a year even more.
Recent and future prices are shown here: https://andelenergi.dk/kundeservice/aftaler-og-priser/timepr...
I don't know of any studies done here, but anecdotally I do know people who have the app version of that webpage and will schedule their laundry/dishwasher accordingly. (And of course EV owners will configure their car to charge at the cheapest period.)
Personally, the saving isn't worth thinking about for me. I run the dishwasher overnight anyway and sometimes the washing machine, but that's to avoid the noise during the evening rather than any economic or environmental reason.
There are other charges that don’t vary by time of day or kWh, so those numbers are only good for absolute, not relative comparisons.
https://www.oeb.ca/consumer-information-and-protection/elect...
This doesn't surprise me a great deal. Personally, the price difference would have to be very high in order for it to affect my usage patterns. It would have to exceed the cost of having yet another complication for me to keep track of.
We’re getting the kids version of market pricing, but when you give people real market pricing without cross-subsidization, they tend to get confused/angry/bankrupt.
I still think they could do real-time pricing with some kind of cap that gets balanced out amongst all users, but the uptake still may not be there. It averages out for those that treat it as noise and still not a lot of equipment out there to take advantage of it at the personal residential level.
They say that the percentage of users who actually do this is somewhere around 10%.
Personally, I value having electric prices being stable very highly. I'd prefer pay higher rates (up to a point) to keep that stability.
(Technically you can choose a tiered pay X for first kWh and then X+Y above that in my system, but if you're in a building, the building gets to decide which of the two every user is put on)
If you don't yet have solar and your site is favorable, I strongly recommend considering it if you can have it installed at a reasonable cost.
[1] https://www.tesla.com/support/energy/tesla-software/autobidd...
https://www.tesla.com/support/energy/tesla-virtual-power-pla...
Edit: Unless you're taking advantage of tax incentives to do it at house scale. Its hard to beat the economics of just being handed free money.
It may or may not make sense depending on your location. Many utilities would prefer to make customer-owned solar a very poor financial choice thru rate design (e.g. very high minimum charges, per-kw-installed solar charges, low daytime rates relative to evening rates, wholesale-rate compensation for exported production, etc). Some succeed.
If household power purchase price doesnt change with time/generation cost, then there is not ability to act faster than the power company.
Depends. It may be more profitable for utility companies, but they keep the profit of the economies of scale. It is almost never passed on to the customer.
If you DIY your own energy system, you're free to keep all the surplus generated by it through the life of the system.
Utility companies have to pay for distribution networks, and generally pass that cost on in the price per kWh. Which you avoid the less you use the grid -- and which then become a higher proportion of the prices the utility has to charge the more people do that.
That just has terrible results most of the time, because it means that people generally ignore or otherwise don't understand what the government is doing, which leads to all kinds of inefficiency and corruption.
But "law requires you to buy this expensive thing you don't want" is simple enough for people to understand and get mad about, and affects enough people to make politicians care.
Woah, I didn't know this. In any case, surely it's legal to have grid service to the house and simply not use it.
> I would not put it past the grid provider to come up with a minimum monthly bill
My electric company (a community owned co-op) has done this for many years. You pay $15/mo no matter what. Your power usage is billed on top of that.
There is a reason home generation wins. It's because retail prices are 3 times what the generator is paid. (That's true where I live).
So yes, in absolute terms power generated by home solar costs more than a utility generating it. But it's not 3 times more, so if you install home solar and use the power, it's always a big win. It will be the same with batteries.
The traditional forms of generating power, coal, gas, hydro and nuclear only win because home generation costs using those technologies (eg, putting a coal mine and generator in your back year) costs far more than 3 times. You can't put wind, or pumped storage in your back yard either.
But solar and batteries are different animals. They are different in other ways too. It always makes sense to over provision solar. The question is not whether to do it, but by how much. So home generators will always be looking to sell power, and since it's free selling it at 1/3 of what they would pay for the same power looks like money for jam to them. It makes you wonder how many utility generators will be left standing if solar takes over the world.
AFTER you finish paying off the financing of the source of home generation. so maybe it'll be a big win for the people in your location after you're gone???
I subscribe to a power company that produces power via wind. So my money is supporting green energy generation. So yeah, it would still be doing plenty. Not really sure why you gotta be so negative about something
A while back there was a thread on the SolarCity subreddit linked from HN where the OP discussed his savings thanks to nice weather, but still figured he had a 20 year payback period on his setup.
That is crazy.
Say a battery costs $10k and a home uses $100/ month electricity. If you assume electricity is free at night to fully charge the battery and meet energy demand, that’s 100 months (8 years) to break even. Real world costs are going to make it quite a bit worse than that.
Sure, let's say the summer months bump the Texas electric bill to $167/month (8$100 + 4$300). The previous model was assuming free electricity. My quick search is revealing that using differential pricing in Texas, the difference from the normal rate (~$.16) and the low rate (~$.08) saves ~$.08/kwh. Assuming you could perfectly offset all usage onto the cheap rate, that would yield a monthly savings of $83.5. Which yields a $10000/$83.5 = 120 month or 10 year payback period.
Then again, we forgot to right size the battery system. This site[0] claims an AC is going to use 16kwh/8 hours. A Tesla Powerwall is 13.5kwh. If you want the battery to fully cover your AC needs alone, you will need at least one additional battery system.
Naturally, we are missing out on maintenance, opportunity costs, grid connection fees, potential rebates, etc, but I think we have indeed landed on a more nuanced model.
[0] https://learnmetrics.com/how-much-electricity-kwh-do-air-con...
The scheme only saves energy if its not optional.
Missouri is moving to hourly rates this year IIRC. EU already is on 60-min day-ahead prices and pushing hard to get to 15minutely prices.