Ok so my findings are that this additional capacitor can cause drain of battery bit really small. I’ve put pv panel 110Wp into the shade during nice weather and production was 2W in the app. LCD showed 0W. During 4-5hours till sunset I’ve lost 3% of battery (from 83 to 80%). When it was completely dark, EB3A turned off so it will not drain battery during whole night.
So it means that self consumption is about 4W but it needs to be measured by meter to be acurate.
So still I think that adding the capacitor is good option. Every produce Pv power more than 4W means the charging of battery so it is worth.