Welcome!
I’ve moved your post to a more appropriate category. The Tutorials and Solutions category is a place to post tutorials, not request them.
OH comes with a fairly flexible charting capability. I would be surprised if what you are looking for isn’t possible but I personally don’t do much with Charts so I can’t offer advice on how to set it up like that. But in general you’ll probably not find much about using just energy search terms since it’s a generic capability. So yes, unless someone has published a widget on the marketplace you’ll probably have to configure this from scratch.
Unfortunately I don’t see a Forecast.solar add-on. Though it does appear to have a fairly straight forward API (see Problem Reading PV Forecast via HTTP Binding from API Forecast.Solar for one example and search the forum for more).
There are also Solcast (see Solcast sendHttpGetRequest).
However, OH’s charting assumes a time series in the past so it might take some work to generate a forecast chart like that. I don’t think it’s impossible but I’ve not seen it done yet. So this too would be something that needs to be built.
That’s straight forward. Some Items and some rules to run the calculations and a widget to show the current Item’s calculated state.