From the article: "My wife and I both drive electric cars"

That probably explains it.

maybe saving money they used more - in other words Jevon's paradox https://en.wikipedia.org/wiki/Jevons_paradox

thus perhaps leading to more global warming

That’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.

20MWh is around what my house used in both 2024 and 2025.

I 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?

Not 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.

I 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. ;)

I'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.

Their 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.

We 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

It'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.

  Heat Pumps: the Future of Home Heating

I 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

Don't be surprised when the answer is "not much". Apply supply and demand to electric power generation. If your grid rate is getting hiked then so is the market price of used solar.

Battery storage tax credit (30%) runs through 2032, must have at least 3kwh capacity. IRS Form 5695.

https://www.energystar.gov/about/federal-tax-credits/battery...

Brand trust?

(Yes, yes: insert Musk related joke here.)

Or you can by a car instead. An MG4 costs less than 20000 euros with a 51kWh LFP battery. In addition to a good battery, it's a great car as well.

I do wish I could have a good, in-depth tutorial on how to set this up myself. Along with (pipe dream) an explanation of how it would interact with my local utility. I worry that due to some silly technicality, I won't be able to export to my local utility, or else I won't be able to run off-grid when there's an outage.

> Battery prices are getting really low, if you're willing to do some DIY.

Willing and allowed. In some countries it can only be done by certified electricians.

Awesome.

Feel you have more unknowns on the safety front? vs. the expensive off-the-shelf. [in the USA, it’d also be “fewer names to sue” in that unlikely tragedy of combustion in home, but no euro/kWh targets there]

We are finally starting to see Chinese prices externally.

It’s been crazy seeing the western home storage market with €/kWh being more expensive than buying a BEV.

https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942...

Did the same, got a solar installer to fit panels on garage and a solis hybrid inverter. They fitted a CT clamp on my meter and a lora device on both sides for it to communicate with the inverter.

Then bought a 16kwh battery for ~£1500, installation was plugging in a positive, negative and ethernet cable and configuring the inverter to use the battery. (if my home insnurer is reading this, I had an electrician friend double check while helping with some other work)

Definitely recommended for anyone who likes tinkering, thousands cheaper than installer pricing.

I had a good experience using EnergySage, a free marketplace that sources competitive detailed bids - it just needs your address and electric bill.

You can usually save more by generating solar locally and using it to power the home and charge the battery, then discharging the battery during peak hours (usually around and just after sunset) to earn the most. Obviously higher upfront capex.

Pure grid cycling is also frowned on by some utilities.

>it seems just investing in batteries and charging

I mean a lot of companies already do this with megawatt/gigawatt installations.

The key is peaking and grid stabilization. If you're a huge provider you can pay for all your batteries in a year or two if there is some large grid emergency and rates skyrocket.

If you're a non-commercial user, it's going to be hard because the provider rates you pay/get paid are much more likely to be fixed at a pretty low rate.

The author pays £0.07/kWh off peak, but can export at £0.15/kWh. The author paid ~£7500 per powerwall which has ~13.5kWh capacity. Assuming full charge/discharge every night, you can make ~£1.08 per day, which works out to about 19 years to pay back.

Utilities normally consider disincentivizing this type of behavior from residential customers as one of the factors when setting their export pricing.

It is essentially a bond return, with the caveat being that solar PV panels will last 25+ years with some degradation and reduction in output. To your point, the best arrangement (imho) is a standing seam metal roof (40-70 year lifetime) with the panels mounted via friction racking with no roof deck penetrations. This avoids the economic cost of pulling everything off the roof to re-roof, and should outlive any homeowner 40 years of age or older. I also expect labor willing to get on a roof becoming more scarce and expensive over time in the developed world, which I think should be taken into account. Your battery storage can be replaced 10-15 years from now at the end of its service life by anyone with a hand truck.

> I'm assuming you re-did your roof before you installed

In the UK I would expect the roof to be tile, which lasts basically forever unless a storm hits hard enough.

I did have to have my panels taken down and refitted, at a cost of well over £1000, because I hadn't bird-proofed underneath them (wasn't suggested by original installer). So watch out for that one.

Almost all simulations I've done across 3 countries with 3 different payback models for selling back to grid (one of the three doesn’t allow selling back almost anything above your consumption), I could never make investing in Solar not being a gamble.

You really need to gamble on odds of replacing equipment being very low for it to make sense. And in practice most people I anecdotally know that run it, after 5-7 years have already done additional purchases. The payback time keeps getting pushed back to the point that when payback will happen your panel will be worthless in efficiency compared to new ones. At industrial / commercial scale it makes sense, but humans like to move houses, and do stuff in the houses and that messes with the payback plans at the individual level.

So either I was in the wrong countries or most people just gamble on the equipment lifetime, but for that I'd rather buy SPY calls, less drama.

Don't forget that batteries and solar panels go down to zero value. Money would have performed better in a high yielding savings account.

I personally like simplicity, I'd rather have money in an index fund and just pay a monthly bill over having a complicated solar+battery+car charger install at my house that I have to manage through various apps and dashboards.

If it is about impact on the world, invest in a clean energy index fund. Large solar farms and neighbourhood batteries operate at a much higher efficiency than domestic installations.

They have a 30% gross margin, they're just soaking up the federal US tax credit (which is also 30% for battery storage and extends through 2032).

Alternatives: https://electrek.co/2025/12/28/opinion-its-time-to-start-rec...

You're comparing the cost of a battery with a full system. That 16 kWh battery requires a ~$3000 inverter to go along with it.

IIRC, the original idea was that they would pull older batteries from circulation when their capacities dipped, and then repurpose them as powerwalls, an application where weight is irrelevant.

This was back when they expected the batteries to plateau at ~80% capacity after a few years, and they had battery swapping on the roadmap, so they needed to plan for a future where they had a steady supply of batteries that car customers did not want.

The idea took hold, but the batteries lasted longer and swapping didn't pan out, so now they are competing with themselves for battery supply.

That's not really apples-to-apples comparison. The Tesla batteries are AC coupled so they work with an (AC coupled) microinverter array. For a DC coupled battery you have to have a hybrid inverter and DC couple the batteries.

Your point that they are overpriced still stands though.

Is delivering back to the grid economical in California? Where I'm from people disconnect solar panels on sunny days because it costs them money to return to the grid.