On 13/01/2021 10:58, jon wrote:

I think a very high capacity Lithium battery would add to the cost/
effectiveness so it could be charged off peak and the main storage
radiator turned on later in the day.

It would also more than double the installation costs and in all
probability have a working life in regular use of at most a decade.

https://www.bbc.co.uk/news/technology-55337192

Thermal store is the least bad option if you must do it this way.

UK's big problem right now is not enough electricity generating capacity
in winter going forwards. It will only take a calm blocking high and the
most of Europe becalmed and we will be having electricity rationing.

Solar is pathetic on grey winters days with the sun barely above the
horizon even if the clouds do part for an hour or so.

--
Regards,
Martin Brown