Thanks for the update @Rob.
I contacted Eon after your suggestion and the ‘over the phone’ quote was the same as Moixa’s. For those who are interested, they both quoted £9k for panels, a battery and installation - just like you said @Rob. Both said it’d be cheaper if the scaffolding was already there (due to a loft conversion at the same time). Both companies said it’d take about 6-8 weeks between ordering and having the installation. Neither call centres could answer any deeper questions, e.g. noise/hum from the battery, battery safety etc.
For me, at that price, it’s less about saving money and more about being more independent (e.g. zombie apocalypse) and having clean energy.
Tesla’s solution is the most elegant, and I’m sure it’s the medium term future of domestic energy production, but they don’t meet my budget yet so I can’t be an early adopter.
Something else which has endeared me to Eon, today: https://www.bloomberg.com/news/articles/2019-07-09/eon-switches-millions-of-u-k-customers-to-100-renewable-power
…now you may have to dig a lot further than the headline to see how true this really is. It may be. But for many companies you find out that they just offset their carbon emissions and have an asterisk next to the claim that you can never find the definition for. It’s sometimes a bit of creative accounting. I hope its true though, I really do.