In addition to this link (Kostal Piko MP plus Werte aus XML auslesen) explaining how to extract live data, I also found a way to extract yield values. (daily and yearly)
Create a Virtual HTTP input with the following URL: http://192.168.1.100/gen.yield.year.chart.js
Create a Virtual HTTP input command with the Following command recognition: \ilabelValueId\i\i= "\i\v
This gives you this year's yield.
The same can be achieved to get the daily yield. Here we use the following URL: http://192.168.1.100/gen.yield.day.chart.js and the same command recognition value as in the previous example.
Unfortunately there is only one yield label in the Energy Monitor, so I choose to display the year (eP).
This is how it looks: