How Big a Solar Battery Do I Need to Store All My Home's Electricity?

However, if you were wanting to use pure lead acid batteries for your house, because you'd be doing slow charge/discharge you'd probably be able to get away with just 1100 130ah lead acid car batteries.

I mean you'd be optimising for peak current, which isn't what you'd want. However it could be interesting to see what happens when you have ~500mega Amps at 48v. (24Mw would heat your radiators up pretty quick. )

for lithium, then you'd need 12-14 secondhand tesla/polstar batteries, which if they caught fire, might be a challenge to contain.

People will park them at home every night, and probably somewhere with a charging point during the day.

Smart house energy management should be able to pick up on that usage pattern and use the car battery for the house while making sure the car is kept ready for use.

In the same way that wifi/mobile/satellite comms can keep us "always connected", the changes in power generation and storage are going to keep us "fully charged".

I have 1000 litres of heating oil in my back garden which is hardly unflamable. 10MWh of fuel.

Every other fire you can stop if you're right there and you catch it. If a battery pack starts to go, you might have a few seconds before the local environment is incompatible with life.

LFP (rarely used for cars) is fairly stable. And sodium batteries are even more stable.

However, you need to consider industrial and commercial use as well as domestic. Can you power a smelter using local solar?

Very few people go fully off-grid, reality is people don't want that. Cost/benefit just isn't there unless you live off in the woods.

So instead, market structures react when penetration % becomes non-neglible. First you start seeing things like fixed-fees (minimum prices to maintain a grid connection, or "first x kWh are included"). And then you start seeing like what's in California with NEM3: the grid-export prices drop to "we don't want your excess solar" so people are incentivized to buy batteries. But because batteries make a system more complicated and expensive, people buy smaller systems overall.

So the "too much solar creates a disconnection spiral and the system falls apart" thing is a bit of fear-mongering. The system adapts, the changes in pricing create different cost/benefit ratios, and if nothing else, new AI datacenters will gobble up any power that doesn't need to flow to neighborhoods.

Battery costs might go down, but the space they take up on your property costs money as well, which only gets more expensive the more urban you are.

The island of Eigg has a micro-grid. Not individual houses, a micro-grid.

The UK is going to be a wind power island not a solar power island, and definitely not an individual solar power island.

I grew up in Australia used to a grid averaging perhaps an hour’s downtime in the typical year. But now I live in India, and not only is the power frequently off for hours at a time (it’s a rare week that lacks an hour of downtime, and five or ten hours isn’t uncommon), the quality of the power is also far lower, and it damages hardware. It’s normal for AC units to need mildly expensive component replacements every year or two due to electrical damage, even with the obligatory voltage regulator in place, whereas in Australia I think most people never need to professionally service their AC until it completely packs up after maybe 15 years. If you’re going to want a decent-sized inverter and batteries anyway to get reliable power, then so long as you can get enough solar panellage, getting those solar panels and more batteries and going off-grid becomes mighty attractive—I suspect a payoff period of under a decade, even with comparatively cheap grid power, partly on the strength of electronics living longer.

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Somewhere along the way, it actually becomes mandatory to be connected to such services. In Australia I lived in a rural town of under 100 people, and I asked if I could disconnect from the town water supply, and was told no. So that was some sum of mandatory daily connection fee for something that I would have preferred to unsubscribe from. (Town water was only hooked up to some outdoor taps, and the toilet; the supply had only become treated/potable five years prior, so every house was still hooked up to their rainwater tanks. In fact, the guy I bought the place from said that twenty years earlier you didn’t use the town water on your garden because it would kill the plants.)

I think that starts to bleed into the "pre paid meter" vs contract argument.

but practically the difference between total self sufficiency and 90% is willingness to fork out cash.

I currently have a 13kwhr battery, which covers my domestic power needs for 75% of the year. (we'll start to draw on the grid in the next few weeks.) but in the dead of winter it'll only cover 20-50% of my daily need (excluding the car)

but for car power, thats a different beast. Even though I don't commute by car, with the charging at home, I now use around the same amount of power as the uk average house. (even with solar and storage. pre electic car era. )

Many services that we use in our daily lives are government maintained services, so electricity is no different than water, sewage, internet, roads, railroads, post, emergency services, public education, public health systems, trash and recycling services, parks and recreational spaces, disaster relief and response, and others.

We should absolutely ensure these services continue to be funded and maintained, because they're often not profitable to deliver. Especially to the sprawling population of the United States. That’s exactly why government support exists and should exist: to guarantee access to essential services that markets alone won’t reliably or equitably provide.

So once the improvements in power transmission are done prices should come down for everyone.

https://en.wikipedia.org/wiki/Balcony_solar_power

https://www.theguardian.com/environment/2025/sep/10/south-da...

To achieve volumetric energy density of hydrogen at room temperature that's on par with batteries (and that's charitably assuming you're using inefficient resistance heating with batteries) you need to store it at a pressure in the order of 100 bar.

You're better off with batteries realistically speaking.

In any case, it all depends on what you want to stand next to. A large explosion, or a multi-day metal fire releasing clouds of hydrogen flouride.

https://youtu.be/JzdnUZReoLM?feature=shared

I do say:

> As solar panels increase in efficiency, it might be more sensible to replace the panels on my roof, or add some onto a shed.

Even in the darkest days of winter, they still generate something (unless they're physically covered in snow) - but they'd need to be 20x as efficient to power my typical winter usage.

2024:

May: 2494 kWh

Jun: 2323

Jul: 1915

Aug: 1634

Sep: 1008

Oct: 442

Nov: 185

Dec: 31

2025:

Jan: 43

Feb: 335

Mar: 980

Apr: 1510

My detached house has less space for solar panels than some smaller homes because all faces of the hip roof are triangular; lots of houses nearby that are semi's or terraced actually end up having more roof space because their roof faces are rectangular.

I managed to have 14x 465W panels total added on the east and south faces of my home, but the installer wanted an extra 40% of the total system price to add 5 more panels (and the 15th they couldn't fit on the south face, for 6 total on the west) because they'd have had to erect additional scaffolding and who knows what else. That was an absurd additional cost so we didn't do it, but that additional generation late into the afternoon would have been great for our peak usage at dinner time. My suspicion is they simply didn't want to do it, because the cost just doesn't add up.

On an overcast day at this time of year I can generate nearly enough to power the "baseline" of the house, but currently I receive 24p/kWh to sell the energy back, and I can charge the batteries at 15p/kWh over night, so I can break even if I can generate just enough to export to cover the night-time charge of the batteries.

I haven't had them long enough to run through winter yet so we'll have to wait and see, but based on the end of this summer, I could probably cover the winter usage with export payback through summer at the current tariff rates when we were generating about 100% more than we were using per day.

I suspect the introductory tariff is far more generous than I'll have access to in a year's time when it expires though.

My guess is the differences in either choice aren't huge, as both solar and battery storage keeps getting cheaper.

Having an electric vehicle can really help, also. It basically soaks up excess solar power of an outsized installation during much of the year (making the payback time on the outsized installation very good), and can be charged away from the house during a few low-chance bad winter days when the outsized installation is enough to power the house but not the car. Electric cars are charged fully about 3 times per month on average in the US, so working around that with smart charging is not a complex challenge in the next decade.

But that is a super interesting question that immediately comes to mind.

I am pretty sceptical about batteries and see overbuilding renewables plus bitcoin mining to monetize excess as a more viable solution.

https://www.volts.wtf/p/whats-the-deal-with-sodium-ion-batte...

LNG or propane would be far superior fuel types for long term standby generators. Periodically exercising a machine that runs on CH4 results in very minimal buildup on internal components. Liquid fuels are much dirtier and can also go bad.

Diesel is used in situations where you can afford all of the crazy maintenance. It's worth the trade off if you can.

Unless you live in a location without much sunlight, it’s better to invest in a solar powered system with a transfer switch to go off grid.

If you size the system appropriately it can recharge the battery by day during an outage and now you can operate off-grid for a very long time.

Diesel generators come with maintenance overhead that adds up year over year. They also contribute nothing during normal times, as opposed to a solar install which can offset electricity costs or even earn money.

If you live somewhere dark this is less helpful, though.

Consumption also matters. Some people have eye-popping amounts of electricity consumption while other households get by with far less. The difference, including heating and cooling costs, is surprisingly large between the highest and lowest households.

Not without exception; there's some draw down after dinner even on the charge up sunny months. But a couple kWh against a 1MW pack is not super super notable. If it were cycle count alone degrading battery it'd still be an almost 5000 year battery (before becoming a 0.8MW battery).

As others are pointing out, we have stabilized chemistries even more, so 5k cycles is pretty low at this point.

Your sources really only apply to Britain and other deïndustrialising countries. American and European energy demand is rising due to electrification and AI.

https://yle-fi.translate.goog/a/74-20138415?_x_tr_sl=auto&_x...

It was actually 1000 times that much.

I concluded that we're all going to need much bigger gardens.