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Good analysis. And kudos to the author for saving money. But still 21.6MWh per year excluding solar production seems too high for a household. I use electric he
by kccqzy 10mo ago
Good analysis. And kudos to the author for saving money. But still 21.6MWh per year excluding solar production seems too high for a household. I use electric heating and drive an electric vehicle, and my household annual energy consumption is about one fifth of that.
- louwrentius 10mo agoFrom the article: "My wife and I both drive electric cars" That probably explains it.
- kccqzy 10mo agoYeah but they both work from home. The biggest reason for putting mileage on the car, commuting, is now out.
- lostlogin 10mo agoA single extra charge in a month can really mess the stats up.
- vel0city 10mo agoAn average EV battery is what, around 70kWh? Add in a bit of charging losses and we'll say maybe 75kWh being generous here, and that's assuming a nearly dead battery to a full charge. Doing that every month is then 900kWh, or 0.9MWh/yr. That's ~4% of the energy usage of 21MWh/yr. An average EV gets what, ~3.5mi/kWH? An average US car does ~12,000mi/yr. That theoretical average EV would then use ~3.5MWh. Two would be ~7. But this author is in the UK, where the average car only does ~7,500mi/yr or so or a little over 2MWh/yr. So for their two UK cars, assuming they drove an average mileage in an average EV efficiency, they would likely have used something like 4.3MWh/yr for their cars. About 20% of their total electricity usage. This drops a good bit if they're really getting closer to 4mi/kWh in efficiency, which is likely if they're not driving on many highways like one does in the US.
- metadat 10mo agoEV charging inefficiency typically loses 10-25% of the input energy, depending on temperature and battery level (low temps are bad, very low or high battery level also bad for efficient transfer).
- lostlogin 10mo agoThat percentage of total usage is tiny, I agree. We have one car and charge it quite often. I just checked last month: 184kwh went into the Leaf. We used 557kwh in total (excluding the car charging). We generated 1170kwh. The key thing for me is the wild energy usage from the house. It’s a lot. Edit: Your car energy usage calculation works out awfully close to what we use.
- bryanrasmussen 10mo agomaybe saving money they used more - in other words Jevon's paradox https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox thus perhaps leading to more global warming
- Aboutplants 10mo agoThat’s about double the average household so I would imagine spending that money and effort into energy efficiency would pay off way better that solar and batteries.
- lm28469 10mo agoThe average household doesn't have two electric cars though
- pixl97 10mo agoYea, averages don't work well when talking about single units without any further details. How many sq/ft is the house? Is it filled with windows facing south? Are they firing a continuous laser beam at the moon? 2-3x usage is actually pretty typical when looking at a single house when comparing to average. It's when you start getting close to an order of mag difference that you're an outlier.
- KaiserPro 10mo agoI have an electric car, one powerwall (pre musk midlife crisis) and 5kw solar. we consumed 6mwhrs in 2025. Gas heating and hotwater, about 190w base because of networking, servers and shit left on.
- Scott_Helme_ 10mo agoHow did you know about my laser?!
- pixl97 10mo agoI saw your xkcd history...
- icehawk 10mo ago20MWh is around what my house used in both 2024 and 2025.
- davely 10mo agoThis number can mean wildly different things depending on the size of your house (and location). I live in the Bay Area, CA in a 1,500 square foot house and consumed 7.8MWh in 2025 and 7.6 MWh in 2024. Digging a bit more into our solar system data: We produced a bit over 9MWh in solar each year and it looks like our Enphase batteries discharged 2MWh each year.
- lostlogin 10mo agoI can’t see any mention of hot water or cooking in the article, which may be relevant. I was stoked at the power saving from turning off an espresso machine a bit sooner, a swapping out a nuc to a Mac mini. Maybe there is a bit coin mining operation in his basement?
- Scott_Helme_ 10mo agoNah, there's no Bitcoin mining, honest!
- cptcobalt 10mo agoNot all homes are made equal: different appliances & electronics from different vintages, etc. I have 2 EVs (Tesla and BMW), an electric oven, and a homelab rack (but no HVAC), and my usage was 34.4 MWh last year — with 100% from Solar and Powerwall.
- lostlogin 10mo agoThat’s an awful lot of power. I’m waiting on a quote for an hvac that uses its waste heat for the home hot water. Im irritated that I’m cooling the house, pushing out hot air, and heating water at the same time.
- sponaugle 10mo agoOn that avenue, I do push hot air from my homelab into my upper garage for heat. If it below 50deg outside I also bring in some cold air from outside. Both are somewhat free offsets for heating/cooling.
- lm28469 10mo agoGet a basic heat recovery unit, it basically has no moving parts (just a few fans) and good ones recover 90%+ of the heat going out of your house. It's almost useless if you don't have an airtight envelope though. All in one systems with water heating are way too complex and _will_ fail relatively quickly, mini heat pumps won't last 10 years, and by the time it dies you won't be able to find a replacement for your specific model
- lostlogin 10mo agoThis makes me sad. I’m in a 1940s house where the lack of it being airtight is a key reason it’s still standing as it leaks and the airflow dries it. Water flows down the inside of the brickwork, and the cavity is well ventilated. Yay for New Zealand housing.
- MisterTea 10mo ago> All in one systems with water heating are way too complex and _will_ fail relatively quickly, ... Can you offer some evidence of this? I don't see how adding a refrigerant to water heat exchanger after the compressor, before the reversing valve, could possibly hurt the longevity of a system. > ... mini heat pumps won't last 10 years, and by the time it dies you won't be able to find a replacement for your specific model Thing with mini-splits is you replace the entire unit so it doesn't matter.
- sponaugle 10mo agoI used about 64MWh last year, not counting what I used for EV charging (Which is on a separate meter). I also produced about 20MWh from Solar. With the EVs I would guess the total is around 70MWh. Some of this extra is certainly my 6kw homelab + HVAC for that. ;)
- micromacrofoot 10mo agoI'm an example more towards the middle. In 2025 I produced 6.5MWh (solar) and consumed 12.7MWh (excluding solar production); this is a family of 4 in a 4 season climate with electric heating and a single electric car. That was my highest year over the past 5 years. An additional EV can really add up, especially if both people have long commutes.
- kccqzy 10mo agoThey have no commutes. They both work from home. I don’t even understand why they need two cars for that.
- bz_bz_bz 10mo agoTheir total household usage was actually ~17.3 MWh depending on what data source you're using for their usage. Given 6 MWh of exports with only 3.2 MWh of total solar production, they are cycling their powerwall to get paid for the fact that their off-peak rate is half the price of their peak export tariff rate which is inflating the number you're looking at.
- UltraSane 10mo agoThat is still an enormous amount of electricity for a single family to consume.
- Dylan1312 10mo agoIt's less than 50kwh a day, high but seems reasonable with 2 electric cars.
- Aromasin 10mo agoHe mentions that he has a server. It wouldn't surprise me if that consumes the majority of that.
- port11 10mo agoPeople need to stop using the old Mac Pros for home servers, jeez.
- darknavi 10mo agoI had a old, cheap, used Dell R710 that I bought used in ~2016 until 2025. It only took a few months of running a new, much more efficient server to pay for its self.
- port11 10mo agoMy EliteDesk G4 idles at 11W with 4 drives, so it’s not too bad. I really wish we could get something cooler, but it does the job beautifully. I see 150+ for the Dell, ouch.
- DamonHD 10mo agoWe brought down our energy consumption substantially over the years starting not so far from that high figure, including swapping out racks of Sun servers for an RPi or two, and we are now slight net exporters of utility energy and with it roughly zero carbon... https://www.earth.org.uk/saving-electricity.html https://www.earth.org.uk/saving-electricity.html
- lm28469 10mo agoIt's high but it really depends on your lifestyle and appliances. If you have a heat pump water heater and heat pump based floor heating you'll use 1/4th of the energy as the same house with resistive water/floor heating. A house which barely passed regulation from 2010 will consume 5-10x the energy of a certified passive house. etc. That being said I think you have to draw the line somewhere. I'd much rather have inefficient appliances (resistive boiler/heaters) and be fully solar powered than spend 50k in heatpumps and other gimmicks that are rated for 10 years and cost a kidney in maintenance and the eventual replacement.
- rokkamokka 10mo agoHeatpumps are not a gimmick - they're an excellent technology with lots of efficient and effective uses :)
- lm28469 10mo agoOverly complex and fragile in the long run, the savings are meaningless if you're already self sufficient. I'd much rather spend the money in insulation and self sufficiency than these voodoo appliances. That's my reasoning my new build house with plenty of land. In other scenarios it might be more beneficial to go for them.
- UltraSane 10mo agoHeat pumps are no more fragile than air conditioners.
- lm28469 10mo agoYes, and that's why I have none.
- mrspuratic 10mo agoNo fridge? That's a heat pump.
- youngtaff 10mo agoI think Scott's usage is high – I think he mentions between £300-400 / month – but then he's got a hot tub, server rack as well as the cars. We still have an ICE car and gas central heating but our combined electricity and gas bill is around £140 / month Plan to go to EV and heat pump in our next house though
- KaiserPro 10mo agoexternal wall insulation and triples glazing first! We did it and made winter ~10 degress warmer, and summer 15 degrees cooler. its cheaper than the solar/battery install.
- HexPhantom 10mo agoIt's more a stress test showing that even with unusually high consumption, solar + batteries + tariff optimisation can still materially change the cost curve
- GordonS 10mo agoI was really surprised too - our family (with electric car and a lot of tech) uses only a third of the energy used in TFA! Still, even with our lower usage, solar still makes sense (especially with a South-facing roof) because electricity is so damned expensive in the UK :(