Wrong pellet calculation
The pellet calculation based on "pe1_L_modulation" does not differentiate between 100% and less. I rebuild the query to calculate the amount of used pellets based on modulation:
SELECT mean("pe1_L_modulation") * (22 / 4.9 / 60) / 100 FROM "oekofen" WHERE $timeFilter group by time(1m) fill(linear)
I do have a 22kW burner, so this would need to be adjusted according to your own oven. Due to the fill(linear) it should work independent from the pull interval (i myself fetch them every minute).