What a year of solar and batteries saved us in 2025 (opens in new tab)

Here in Europe, we got more than a month's worth of foggy, cloudy weather (something that looks like will keep being a thing), which is something I became painfully aware of as an owner of a solar setup.

No amount of battery banks can tide over such a long stretch.

By the way, let me ask you - considering your location, you must be getting a lot of snow, how do you deal with it, is it a problem? Panels are quite hard to reach on the roof.

My partner works in the field and we once talked about this. I think the idea is that individual consumers’ and businesses’ batteries can serve the grid as needed. For example, if your car is fully charged and you don’t need it today, it can top up local needs.

So I think the writing isn’t on the wall yet for line price going up, although I’m of course talking of a) Belgium, and b) a future that could go wrong if utilities don’t fund smart metering.

An interesting possible is the grid becoming smaller. Neighborhood scale.

In many places from Central Europe and further north dealing with arctic cold spells and dunkelflautes are near impossible for a home solar and storage setup.

But you also don’t want to pay for a continental scale grid the remaining 51 weeks.

So in your neighborhood add some wind power and a good old trusty diesel/gas turbine running on carbon neutral fuel and keep the costs to a minimum.

This is addressed by crowdsourcing generation and storage to household batteries. Surplus energy is banked locally instead of being dumped on the grid. The utilities buy it back from homeowners at wholesale rate under demand response programs when they can't meet demand.

Many cities in north america you cant get occupancy without grid tied electricity, so every house incurs the coat of bas government policies on transmission. Its why i havent bothered with this yet. The optimal setup for here is natural gas generator, some battery and some solar given how stupid the fixed charges are here but you cant live in your house if you disconnect from the grid (even better would be for fuel cell manufacturers to offer something sized for a house so i can get hot water put of it as well and a silent unit)

IMO, there's close to no bad usecase for batteries. In almost all their applications, they end up spreading out power consumption favoring cheap energy for expensive energy.

If a datacenter installs a solar array + a giant battery pack for their power, that's much better than them heavily relying on a natural gas plant to generate power when the lights are out.

The commercial options would fall further in price probably than consumer prices. If you buy in bulk, you do research to find the most cost effective options. That's a common pattern with many things. I don't see why batteries would be any different. If anything, I'd expect consumer batteries to have higher margins. Tesla batteries are a good example probably. At those prices, a Tesla car would be unobtanium. Obviously they charge a lot less for batteries that go in a car.

The reality is that many battery factories might be operating at 40-50% capacity only. Exact figures are hard to come by but there are lots of warnings about over production, surpluses, etc.. That spells a lot of trouble for some of the newer battery producers promising more efficient batteries. Because unless they price match, they price themselves out of the market almost immediately.

Why does it have to be zero-sum?

Why not commercial demand creates the economies of scale that bring the residential stuff down in price with them?

Its weird to read about Schneider Electric not bothering with brand awareness. They aren't a household brand, sure, but they are well up there with Siemens and the like in industrial/b2b sector and their marketing budget is allocated accordingly.

There was some research[1] that strongly suggested that varied use makes them last much longer than the steady use that most battery tests do. That is, bursts of high-current draw followed by moderate draw etc vs the constant current load typically used when evaluating battery performance. From the paper:

Specifically, for the same average current and voltage window, varying the dynamic discharge profile led to an increase of up to 38% in equivalent full cycles at end of life.

This was unexpected, hence explains why they fared better than predicted.

[1]: https://www.nature.com/articles/s41560-024-01675-8 Dynamic cycling enhances battery lifetime (open access)

What do you mean? It did pan out for Tesla. Faking a single demo granted them 75% more ZEV emissions credit government subsidys [1]. That increased their profits by hundreds of millions of dollars.

All they had to do was go on stage and “swap” a battery without any clear video of the process and never “demonstrate” it ever again.

This is a company known for faking prominent demos like the FSD demo (where it crashed into a wall during filming), the solar roof demo (where they used regular roof tiles and claimed they were solar panels), the optimus demo (where they were teleoperated), etc.

Assuming they even did a battery swap, for which the official demo presents no clear video evidence, preferring overhead views over a close-up of the process or a glass enclosure to see the inner workings, it was at best a one-off custom-made device at the time. The one battery-swap station they claim existed has zero stories of any actual battery swaps, instead only evidence of it operating as a regular Supercharger [2].

[1] https://thewaroncars.org/episode-88-tesla-is-a-fraud-with-ed...

[2] https://slate.com/technology/2022/05/elon-musk-tesla-twitter...

> Any idea why swapping didn't pan out for Tesla?

~~Two~~ Three things:

1. California changed the rules shortly after Tesla demonstrated their swap station, which practically eliminated the tax credit for battery swap (at the behest of lobbyists for Toyota, who were backing Hydrogen Fuel Cell technology). Specifically, the credit would be prorated by the percent of “fast refueling” sessions a car did, so EVs primarily charged at home received almost nothing while HFCV got the full credit. Building swap capability adds complexity to the car (think about all the fluid connections), which isn’t worth it without credits.

2. It was also around this time that a Model S ran over an anvil (or something) which punctured the pack and started a fire. In response, Tesla added an aluminum battery shield, which further complexifies swapping and was probably the final nail in the coffin.

3. The logistics of storing your very expensive battery (so you could get it back later) basically make the system unworkable. When the Tesla swap station at Harris Ranch (you can still see the former building, next to Harris BBQ, which currently houses the restrooms) was operational, you had to make a reservation some hours in advance so that Tesla could have a pack ready and be ready to take your pack to/from storage.

3a. Gresham’s Law. Without eventually returning the pack to the original owner, there is an adverse selection problem: people with very weak packs will gladly roll the dice on a swap, but those with brand new packs are reluctant. So the average quality of packs in the swap network will quickly decline creating a death spiral.

3b. You could probably fix 3a by leasing the battery (or selling battery-as-a-service) but car buyers mostly don’t like that, especially back in 2013.

Probably because the economics just don't make sense here. You'd have to have so many compatible cars on the road, driving all day with no opportunity to charge. I'm having a hard time imagining a place I've been to in North America where that'd seem logical.

> they are doing that in China

Are they actually doing that at scale?

> which would probably hae been another 3-5k if I could have found someone to do it.

Yo. If you can find an electrician to stop by my house and turn a light switch off for less than 1000$, please inform me. I got a quote for 25k$ to install a system that size, and that price. City code has me by the balls: I can't modify my main panel without inspection, the inspector won't show up without a licensed electrician, and electrician wants the labor. I pointed out that we're talking 8 hours of labor — call it 2500$, lawyer money — and he was like "what's your choice". I'm in Texas.

This is still not an accurate comparison. I'm not a Tesla fanboy but of all of the major players in the non-diy game (Enphase, Franklin, Tesla, Sol-Ark) they provide the best value for money, and are impressive pieces of equipment.

The EG4 18k has 11.5 kw backfeed capability, with a rather pathetic 65ish amp in-rush. Obviously 18kw usable solar capacity(they technically let you land up to 21kw, but only 18 is usable).

The Powerwall system you outlined can take 60kw of usable solar input, has 34kw standing backfeed capability, and a whopping 555 amp in-rush (not a typo, it's 185 amps per unit).

Not to get in to warranties, etc.

I'm talking about something a bit different - the Ioniq uses a V2L, which means it has an onboard inverter that generates AC mains voltage through the plug, and can be used to provide equipment directly.

What I'm describing is using the cars DC charge port and connecting it to inverters DC battery port.

Find an electrician who will inspect and sign off on your work. It's not illegal as licensed master electricians have mechanics do all the grunt work who are unlicensed. The electrician vouches for his employees work which legitimizes it. No different than you doing the work and having the electrician inspect, call out issues to fix, and inspect again until no issues are found and sign off.

Surely it only needs to be signed off if you intend to sell the property with them or sell excess back to the grid. If youre just using the batteries how is anyone going to know?

Theoretically a good choice, but where I live, just doesn't work. Either they just say "no thanks" or they will be more expensive than letting them do the whole job.

I got the "trick" recommended to do the things yourself, then call a certified guy, and say "look, I contracted a guy, I had no idea, he came did everything, but I got a bad vibe, I would like you check the whole installation". But it also does not really work, they will come with a contract, where you are enforced to contract them to correct any findings. And boy they will find things then...

I would appreciate this write up as well. Looking to do a DIY setup.

> especially not to spec torque on terminal connections and botched crimps leading to hot spots

This was indeed my greatest concern. However the battery came with pre-crimped very solid DC wires, and nice push connectors for the battery itself. The battery also has an integrated DC breaker (great!).

The system runs 3KW max, so I just added an additional breaker (with RCD integrated) in the conduit box. In NL this is something a DIY-home owner easily can do themselves :) (just use the right solid/flex stranded cabling for the connectors, etc...)

> LFP batteries are as likely to burn down your house as a stack of wood is.

LFP batteries are much safer than past chemistries, but this statement is way too broad.

High power batteries are always more dangerous than something like a stack of wood, because batteries will gladly dump their entire energy capacity very rapidly into a short.

Even if the battery itself [mostly] won't self-immolate, the entire installation can be a fire hazard.

Treat them with proper respect.

> botched crimps

On a tangent, I’m amazed at how bad most random crimps I see on the internet are. Also, the number of people who debate the use of solder on crimps without discussing potential issues with said solder is too high.

Fitting blocks (basically shaped plastic) around the edge to prevent birds from getting underneath and nesting. Merely landing on the panels isn't a huge nuisance, but nesting is.

Stay tuned, I have an idea to soak up global capital for these projects.

This is factually inaccurate. Solar PV panels will continue to produce power at 80-90% of rated output after 25 years, and battery storage will still have 80-90% capacity. I'm sure you can understand that as long as the system is storing and producing power at these levels, its value is not zero.

> while the initial principal of your bond investment will remain intact.

As long as the bond issuer remains solvent. How much do you trust bonds that yield 9% to retain their full value for 25 years?

Outside transfer switch and a 10-20kw portable generator is like $4-5k. It requires manual switching but it works for us in our hurricane-prone region. Helped with last years 1 in a 100 year winter storm in our southern region.

Battery/solar doesn’t make sense in my opinion. Too many years to break even like this parent comment said and by the time you break even at 10 years, your system either is too inefficient or needs replacing. At least with the portable generator, you can move it with you to a new home and use it for other things like camping or RVing.

Is it priceless? I literally wouldn't pay more than $200 to have electricity for a day while the whole neighborhood doesn't. Anything more and I'd prefer to just keep the money in my pocket to be honest.

In my country I've never had to deal with more than 15 minutes, twice in my life. In other countries its sometimes been a day but really I just go on with my life.

Whats funny about that -- is you assume thats the case - but a lot of solar isn't installed to be backup power. With Storage yes, but straight up solar -> no.

Well there are other, far cheaper ways to get that.

99% of systems are grid tie, so unless you’re spending another $7k for an ATS and associated infrastructure or you’re 100% off grid, your power still goes off.

This is also true of heating and cooling, and I've never understood why we (in the US) build relatively dense housing communities but don't implement things like this. Having a separate air conditioner for each home, especially in a condominium/townhouse complex, has never made sense to me as it's so inefficient compared to central heating/cooling.

It could be as simple as a different model. In one of those it was easy to make it feasible if you had no cap on how much to sell back, but it was limited to consumption plus like 10% or something like that. Since the property used very little energy but had a big roof we thought itd be a good thing to produce green energy while making a little money or even just breaking even, but to break even we'd have to use way more energy which was completely against the original objective. So its not like the technology isn't able to do it but the rules can make it very hard and a few years less of operation for some components make the math very difficult if you're conservative and want to ensure break even within some reasonable timeline

> Do they fail outright at around 10 years, become unsafe, or do they just lose capacity?

LiFePO4 generally degrades to 80% capacity after 10 years, that's it. Safety isn't an issue.

Presumably an exponential decay, as for most tool lifetimes.

Sorta, kinda, it depends.

In my house I only run LED lighting and an occasional oven, some phones and laptops, a cycling fridge and two weekly wash cycles, in other words, virtually no electricity. I'm at like 2 kWh per day.

The ~45 kWh a day for this family is gigantic compared to mine, like >20 of my homes in one.

But I don't have an electric car, nor electric heating or cooling, nor an electric stove.

If you have say a standard electric car like a Peugeot 208 which uses 15 kWh per 100km, and you both drive one hour (say 60km) to work and back, five days a week, that's already 25 kWh per day.

My heating bill (gas, europe) is an order of magnitude of my electric bill. Even if I'd electrify it (cheaper), it'd likely be an additional 10 kWh per day.

If you have slightly more fancy lifestyle (they run home-servers and a hottub for example), you can easily get to 45 kWh.

I think the fair comparison is to look at a household total energy expenditure (energy & $). My household has a low electrical share, theirs has an almost exclusive electrical share.

He mentions that he has a server. It wouldn't surprise me if that consumes the majority of that.

It's less than 50kwh a day, high but seems reasonable with 2 electric cars.

Get 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

On 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.

You just need an air source heat pump water heater and install the water heater next right to the outdoor unit for the HVAC.

Yea, 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.

An 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.

Heatpumps, Shmeetpumps

Overly 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.

It depends where you live, where you get your electricity from, for how much, &c. It's an amazing tech don't get me wrong, and of course youtube tech nerds love these kind of things, no surprise here, I just don't think it's the silver bullet everybody imagine it is.

UK government subsidy support for air-to-air was announced a couple of months ago:

https://www.gov.uk/government/news/discounts-for-families-to...

A lot of people in America, sadly. Mini splits cost $250 to install in Japan and frequently $10k/head in the USA.

I'm talking about geothermal water/water installs for central heating.

No one is heating their place with air/air heat pumps besides americans who haven't figured out that heating spaces via air is shit tier in term of comfort and efficiency

Find a solar coop if you can to avoid the sales pain. They will assemble a group of homeowners and bid the entire group install out to achieve cost efficiency. Ground installs are cheaper and easier, imho, whenever possible (but depends on land availability and favorable solar insolation).

http://solarunitedneighbors.org/ | https://solarunitedneighbors.org/locations/

My provider wasn't PG&E, and I don't know if they do the same, but there's a fixed $30/mo service fee for connecting to the grid, regardless of how little power is used, even if its negative.

But is that rate always positive? Where I'm from during peak sun hours, the rate is negative and you end up paying money to deliver money to the grid. They do this to incentivise you to decouple your solar installation during peak sun hours so the net doesn't get flooded with too much energy.

This is for solar only installations. People are advised to flip the breaker of their solar installation when energy prices are negative as it would cost them money if they deliver electricity to the grid. This helps to reduce strain on the grid.

Yes, it does. I haven't tried it as a do not have the cable for it, but the user interface for discharge is there and the manual also talks about this feature.

It's probably not ideal for running a full house (as it would require some other electronics and installations), but a couple of appliances should work.

Well, people who live somewhere where they need heating use more energy to stay alive than those who don't. Too bad California is so expensive because we could decarbonize the US significantly just by making it affordable for people to move there from Northern states.

This is totally wrong. I work in the industry. Solar panels should last for 30 years, but they degrade in capacity by 0.5 to 1% per year, depending on environmental conditions (temp, radiation, etc). Lithium batteries from tier 1 suppliers can last at least a decade of regular use. It depends on how their cycling and state of charge is managed. If you keep them between 20% and 80% charge, they can last incredibly long.

What gives you that impression? Unless you're looking at the pre-9/11 grid powered by Enron™, rolling blackouts aren't a big deal in California. I think since 2001 there was a single 2 day event limited to certain regions, I don't know anyone personally who lost electricity due to rolling blackouts.

The CA grid has also scaled up battery storage surprisingly quickly. A few years ago it was in the single digit mWh, not really a meaningful fraction of the grid. Now it's measured in gigawatt-hours.

Your link does not support the idea of a supply deficit, at least that I see. Propel panicked about lithium under supply, prices surged and didn't even affect battery prices much, and now we are in oversuppply. The worst that can happen is lag time between demand increase and supply match, and there are substitutes for all key metals for most applications, even copper.

Every country will have to figure out how to supply its own power, but Sweden's seasonal variation in renewable resources is not likely to be fixed by batteries, even though batteries will be abundant and in massive supply throughout the rest of the world. If Sweden can't figure out, or merely can't, take advantage of great cheap new technology, they will be at a disadvantage compared to countries that will

> I know California has rotating blackouts already as it is

You don't know that because it's not true. Due to planning not taking into account climate change, there were a few days with demand above expected ability to provide capacity, but there were no blackouts because people were asked to voluntarily cut back on excessive cooling. That mere ask was more than enough to get through the few days. And it was fixed the next year, by what? By batteries! Adding nuclear wouldn't have helped, but batteries were the perfect solution. Perhaps nuclear can help Sweden, but it will be far more expensive than the solutions available to other countries.

It is quite funny that what I thought was US propaganda has been spread to Sweden for repetition. Even including the IEA report that doesn't say what people claim it says!

How would 2 weeks of battery help you in that situation? The winter lasts a lot longer than 2 weeks. So after 2 weeks of no sun, wouldn't you be just as screwed as if you had 1 week of battery storage?