Comment by bjackman | Hacker News Reader

Comment by bjackman | Hacker News Reader

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I wonder if we'll start to see gimmicks in home appliances for taking advantage of variable prices.

Like for EV charging I assume it's a basic requirement, you simply wouldn't buy a car that didn't let you adjust the charging schedule based on cost.

But what about... Freezers? Maybe there are scenarios where your freezer could drop 20° below its usual temp while prices are low, and thereby avoid running the compressor for several hours while prices are high.

What about a tumble dryer button that says "these clothes are fine to stay wet for up to 8 hours, dry them at the cheapest moment during that window"?

TBH I doubt these things would really pay for themselves but as a consumer I'd still be tempted by the "lol, neat" factor.

Also I assume the local-LLM heads are already finding ways to have their agents do useful work while the GPU can churn tokens for almost-free.

Also makes me think of fun Home Assistant workflows. Like, "when energy is expensive, just try to keep the house between 16-26°. When energy approaches free, I want to live at exactly 20°". (I assume heat pumps also have ways to take advantage of this in more roundabout ways).

I think freezers would definitely be a gimmick as they don't really use that much power.

I can see it being a nice feature for higher-load tasks though, e.g. my dishwasher uses about 1.8kWh for a cycle. On this tariff it's trivial to compute the best start-end time based on the 30 minute price windows, so if the dishwasher could do that it would be pretty sweet. Right now my dishwasher just supports a 3h delay function. I wouldn't mind if my dishwasher had a (local) API you could hit to control its schedule. Sadly this usually comes with some cloud requirement though.

I think freezer could be comparable, no? How many cycles of dishwasher are you running per day?

Our Mitsubishi heat pump water heater has integration with some solar systems and weather services to attempt to time hot water production to solar peak.

We don't have solar panels but have a solar energy plan (cheap during the day, expensive during dawn/sundown, average overnight with fixed hourly schedule independent of actual production) so for us it's just programmed to follow a fixed schedule of prioritizing filling up during the solar hours and 100% forbidden from filling up during the expensive "duck curve" hours.

Things like freezers don't take a huge amount of power. It's definitely about things that do space heating/cooling. The traditional approach is to put your electric water heater on a timer. That way you can schedule your hot water use on a consistent schedule but only heat the water at night when you can be sure the rates are lower.

In my case I've got a contactor on the house power board that disconnects the hot water at night, so it's only heating off solar power. You can also get specialised solar diverters that do the same thing, but they cost literally ten times as much and only squeeze a tiny bit of extra efficiency out of the system.

If you do go down this path, make sure you insulate the crap out of the cylinder and surrounding water pipes, mine only heats once a day and that's once the sun's providing the power for it.

I second this. I live in Spain and put solar panels on my roof. I have no batteries. In the last 2 years, the price of the energy returned to the grid has been 0 or even negative. Therefore I started running automation using Homeassistant and I'm stuck at appliances that cannot be simply turned on and off with a power switch (i.e. my freezer, the AC, washing machine etc). If someone could produce a refrigerator that I can control via an open protocol(i.e. ZigBee) it would be awesome!

You can basically do that today if you wanted to by buying consumer grade batteries and smart switches. A whole house battery would be better, but it's more expensive to install.

For the tumble drier and dishwasher, those usually come with time delay features. That's usually good enough if your goal is to timeshift a load.

I have a battery for my fridge not for this purpose, but because I'd rather not have a power outage spoil my food.

With "smart" appliances that can be controlled, there's often a community integration to HomeAssistant ... and then there's the free EMHASS addon which will optimise for profit, or self consumption based on energy prices (both incoming and outgoing) as well as any on-site generation (e.g. Solar PV) batteries etc. etc.

Neat piece of open source software.

I'm following battery prices and you can now get 25kwh for 3.5k. This will be a solved problem a lot sooner for a lot of people.

A heat pump house uses perhaps 40-50kwh in deep winter.

> A heat pump house uses perhaps 40-50kwh in deep winter.

Over what time period, and where? My geothermal system draws about 1200 watts when heating our large house on the coldest days of the year

Argh... i wanted to write 1-2 days.

I meant it as a short buffer

Ah gotcha. That seems much more reasonable!

Just buy a home battery. Sheesh, there were solutions to problems before LLMs

Yeah this is the simplest solution. I'm hoping my next EV can do V2H and act as a home battery.

Yeah, but that’s strictly worse for some of these examples. You can’t overcome the loss of energy just going into the battery and getting it back and the there is the huge cost of the battery itself.

The freezer example would require like $10 of electronics assuming there isn’t already a WiFi chip in it.

Many homes in Norway has this. Its a smart plug in your fuse box. For me it offsets EV charging untill the electricity is at its cheapest, it also cuts down on heating for the peak hours etc etc.

There are devices to store hot water.

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