I did try to make it clear in the article.

We're powering 2 x EVs, have two adults working from home full time, I have a server rack under the stairs, and we have a hot tub outside.

Absolutely — tariff choice, storage, and automation make a huge difference.

The article isn’t claiming this setup is universally optimal, just showing what’s possible when those pieces are combined and used deliberately.

We had an expensive solar install due to restrictions around our roof, so the solar would typically have been cheaper.

Another consideration is that battery installations in the UK are charged at 20% VAT, but if they're installed as part of a solar installation, they're charged at 0% VAT. So even if your main interest is in getting the batteries, a small solar install might make sense because of the savings.

The only restriction placed on you is the export rate, which is provided to you by the DNO here in the UK. We had a limit of 3.8kW placed, which is programmed in to the batteries by the installer.

Octopus also have more flexible battery export tariffs if you want to explore those: https://octopus.energy/smart/flux/

Nah, there's no Bitcoin mining, honest!

How did you know about my laser?!

I saw your xkcd history...

Thanks! Sometimes the simple tricks are the best ones :)

There is no reason to differentiate between free certificates and paid certificates. The process works in exactly the same way for either.

obviously, that's why I asked.

EDIT: I see now that the comment I responded to has been totally edited, so the responses don't make sense anymore.

If you were to use the same private key for the 4 certificates then you could seamlessly switch between whichever leaf certificate you wanted to serve to the client. I'm not aware of the ability to send multiple leaf certificates to a client for consideration though.

Let's Encrypt can issue from an ECC chain, I've tweeted[1] the details on how to enable your account for that.

[1] https://twitter.com/Scott_Helme/status/1392101598852222976

What's the shortest chain-size that those free CAs can offer (assuming android>=5.0 devices)?

It would be great to have a tool somewhere that matches client handshakes & supported CAs vs server config & choice of CA chains

They're all 3 certificates long (leaf/intermediate/root) apart from Let's Encrypt which, due to their cross-signature, are 4 certificates long for ECC.