I have an smart meter, which openHAB reads out for consumption and counter
I’d like to have a chart, which tells me nightly consumption vs during the day consumption
(average consumption 8:00 till 18:00 vs average consumption 18:00 till 8:00)
of course I could insert a Proxy-Item, wich gets updated every day, but I’d like to do that retrospective for the last year
That means you need to work with persisted data.
Either some complicated scripting for Grafana or something, to deduce from existing data.
Or, back-loading calculated daily Item into your dataset.