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 had a solar system installed last year. During the day, from around 8am til around 5pm we are "off grid" in the sense that we can generate more than we use.
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.
I moved to a house with a solar system in October. I now make a point to run the dishwasher and dryer during day time hours. And avoid using the dryer on cloudy days.
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.
That's in the game plan for 2024, no question. My new home came at the cost of doubling my commute distance. An EV charged by my own rooftop would be better for both the planet and my own bottom line.
Edit: Any chance you're in the US? If so, what EV are you driving?
I'm in the south of France, owning a Tesla Model 3 since 2019 now with 104k km on the odometer (152 Wh/km average). Before that it was a Renault Twingo v1 2006 model.
I think the implication is that we'll see a further split around pricing.
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.
Recall your entire house is a thermal battery too!
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.
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.
Just buy a 240v DPST 24 hr mechanical time switch and wire it into the electric furnace circuit (or furnace fan circuit if you have a gas-fired furnace). Intermatic makes them.
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:
French's "fil pilote" to control electrical radiators is quite bullet proof in this regard:
No power on command wire = comfort thermostat, full power = "eco" thermostat, and there are other more convoluted signaling for various modes (send only positive voltage, only negative, only a third of the phase) , including simple anti freeze mode. There is an off command as well, but you really can't send it accidently.
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"
> In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Battery - are extremely flexible.
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.
> EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid.
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
> All the more important to ensure this additional demand is flexible.
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.
My energy provider (BGE) used to offer a program where you could get a rebate in exchange for letting them control your hot water heater and/or thermostat. The HVAC portion is still running, but only for people who signed up prior to 2020. The water heater program has been completely stopped since 2021.
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.
This is how things are done in NZ already. Most electricity company have contracts with two tarrifs (sometimes even more), one normal one and a second significantly cheaper one where the circuit is controlled by the power company and they can turn off things when there is hight demand. Typically you'd put your water heater, electric car and other things on this circuit.
I the more long term, exchanging resistive water heaters with heat pumps is the way to go (and already done throughout Scandinavia)
This is an interesting thought. There are already some energy meters you can add to monitor all of the circuits in your house. It's a short step from there to have smart breakers or switches to help retrofit old-fashioned heaters, radiant systems, etc as thermal storage. Electric buffer tanks may become a cost effective installation when paired with an on-demand water heater and time-of-use electric pricing.
My (Swiss, small) provider just got rid of differentiated pricing "for simplicity sake". On the other hand they continuously increase the solar installations, so I really don't get their point. But I'm not an economist so...
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.
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.
> But it turns out people don’t care and didn’t bother with enough load shifting to cover the cost.
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.
I checked my electric provider and although I said in an earlier comment that they don't do this sort of differential pricing, I was incorrect. They've been doing it for years now -- but it's optional and you have to opt in to it.
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.
if you have the choice, you'd have to run the numbers, but then you create adverse selection issues.
(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)
This is where I'm really intrigued of all-house battery packs like the Tesla Powerwall (it's the only name of one I'm familiar to call out). I like the idea that it charges at night during the lower rates, and during the day the house is powered from the battery. Just haven't seen any longevity reports on them in general vs brochure data.
One thing to consider is that if that's profitable to do at house scale, then it's probably even more profitable to do at grid scale and you'll likely be out-competed by utility companies.
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.
> if that's profitable to do at house scale, then it's probably even more profitable to do at grid scale
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.
This brings up an interesting consideration. Is it possible that in the age of solar, power grids are simply uneconomical in areas of insufficient density? That people in more rural areas would be better off not having a grid and just installing rooftop solar and batteries instead? My gut tells me that the added reliably of a grid is probably worth paying 3x the price, but its hard to be sure.
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???
> One thing to consider is that if that's profitable to do at house scale, then it's probably even more profitable to do at grid scale and you'll likely be out-competed by utility companies.
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.
Good point. Seems like a problem with the utility company's pricing structure if consumers can avoid like 95% of the costs of grid maintenance without having to become fully independent of it. I wonder if eventually they'll have to split electric bills into a fixed "connection fee" and a variable "usage fee".
In a lot of urban locations, it is not legal to have a residence that is not connected to the grid. If you have home generation capabilities and storage that means you take the least amount from the grid provider, you can be technically still connected to the grid without using any power. If this continues, I would not put it past the grid provider to come up with a minimum monthly bill so it is impossible to have a $0 payment. Otherwise, who's going to pay for the administrative costs of having you as a customer?
The rational thing for voters to do is to mostly ignore what the government does unless it directly impacts them in a way they can understand well enough to rally around and get it changed. Which, it turns out, is mostly what they do.
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.
> One thing to consider is that if that's profitable to do at house scale, then it's probably even more profitable to do at grid scale and you'll likely be out-competed by utility companies.
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.
Their alternative is to find some way to generate a lot more cheap electricity after sunset. If whatever they're doing can't beat the cost of solar panels on your roof + batteries and a small generator to top them up in exceptional circumstances, people will just stop paying them altogether.
An individual can take action now whereas the grid scale action is molasses like. It's even worse when your state is not in the pocket of but the actual pocket of Big Oil
If you claim is that "An individual can take action now" by installing a battery to charge at lower rate, then the question of if they can actually purchase power at that lower rate is fundamental.
If household power purchase price doesnt change with time/generation cost, then there is not ability to act faster than the power company.
And much of that does is nowhere near the real cost differences. I might see a difference on/off peak price difference of 0.05 on a $0.40/kwh, but wholesale prices fluctuate from negative prices at peak to much higher rates.
And that has precisely squat to do with my intrigue into looking at a system like this. If it didn't make sense, I wouldn't be interested. So what's your point exactly?
> If it didn't make sense, I wouldn't be interested.
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.
Does this reduce your energy usage though? You're still using the same amount of power during the day. So it saves you money, and takes some load off the grid during peak usage. What does that do to reduce emissions from power generation? Without solar, you're still charging off the same infrastructure.
As if someone trying to save money is such a ridiculous thing to do? WTF?
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
Do you even actually save money, accounting for the financing and installation of the solar panels?
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.
I never even suggested solar. I just want a battery pack that charges when grid prices are cheap, and powers off battery when grid prices are high. Complicating it with solar is beyond the scope of the original intent.
That seems like it would be hard to ever make a financial return.
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.
As they say, "location location location". In a Texas summer, it is easily 3x that per month for 4 months out of the year for a house. So, that's 12 months in one quarter based on your math. The vast majority of that is just running the A/C. So again, this makes much more sense when you look at the nuances vs just some lame internet posting of using averages. If it makes no sense for you, that's too bad, but to come out with broad brush comments alluding to it not making sense ever is just naive.
I guess you could further insult me or provide your own napkin math.
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.
Tesla warranties the Powerwall for 10 years, 15 years if part of one of their virtual power plants (orchestrated by Autobidder [1]). Look into the 30% federal tax credit for it, as well as state, local, and utility incentives.
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.
Solar doesn't work for my property. There are too many trees doing exactly what they were intended to do by shading the roof top. Otherwise, it would be great as the roof alignment is pretty ideal.
In my area, summer "peak hours" often make up half my electricity usage. The off-peak hours are the other half. The price at peak times is more than double the flat rate, but only 30% cheaper for off-peak. I'm already reducing my energy use as much as is comfortable, if I want to maintain that I'd be paying more money than the flat rate.
