How big a solar battery do I need to store *all* my home's electricity?

> Best is to have some type of long term storage like a Diesel generator

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.

No, LFP is 8k-12k cycles, and sodium are expect to be 15k to perhaps 20k cycles. This is reflected in the manufacturer warranties, and many sources. Here's one:

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

(Author here) My roof is full on both sides. There simply isn't any more room.

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.

In our part of the world, solar production during winter is incredibly low or 0 due to it being very cloudy, days being much shorter, sunlight angle on the panel very suboptimal. No amount of additional panels will get you through that streak.

Germans seem to be rather fond of balcony solar

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

You forgot to mention anybody who has a yard that gets full sun can mount panels there as well. As far as fires you can say same thing about all the fires that currently occur because of propane, gas, and heating oil. Those have become some engrained in society for so long that you don't even think of that as a "fire hazard therefore you shouldn't even have it".

Solar and renewables in general are starting to reduce generation costs.

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

The trouble is the capacity is in the wrong place; the UK closed coal plants in (defunct) coalfields in the middle of the country, and built offshore wind farms which tend to be further north. There's plans for an offshore north-south connector to help with this.

> Then the grid starts to degrade due to lack of maintenance, and the people that can't afford local storage become dependent essentially on a government maintained service.

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.

> Why connect to the grid if you are self-sufficient?

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. )

There's a certain type of person who fantasizes about being off-grid, but the few that actually live it know the hassle and generally want to get back on if feasible.

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 do not think this will happen. Getting most households to be self-sufficient is probably not as cost effective as centralized grid. One there's the economy of scale. Second, any peaks and troughs will generally be balanced out between households and the overall buffer (aka reserve) needed could be lower.

If local storage becomes cheaper than the grid but some people can’t afford it (why, capital costs?) then the government would be better off addressing those capital costs directly.

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

It's not the way that it was originally meant, but this is another interpretation of the phrase "energy too cheap to meter".

I'm fully off grid today with no issues, even had power company remove power poles. I do heat with wood however. AC in the summer is no issue since that is when I get the most sun anyways.

This doom-loop is often repeated, but reality is far more complicated.

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.

I once did a related calculation on "How much of my garden do I need to dedicate to coppiced willow to heat my house for a week per year?"

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

And the price of the egg?

> Compressed hydrogen with a fuel cell is the obvious solution.

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.

Compressed hydrogen is no joke. It can escape most containers, actively degrades many grades of steel, has a very low ignition energy, and will explode over an enormous range of air/fuel ratios. Definitely not something to keep anywhere where you care about the roof :)

Extremely underrated how important just a small battery is for autarchy, very useful site.

I think he can't imagine 3x'ing because he already has his house covered and only the shed roof remains empty.

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.