Hello Kai,
its pretty much all older post in the UI section ( https://community.openhab.org/c/marketplace/ui-widgets/75I am afraid.
but here I can give you two I have explicitly seen it :
https://community.openhab.org/t/yet-another-energy-flow-widget/162619
or
https://community.openhab.org/t/mainui-tibber-price-chart-widget/154043
Best Mario