Is this the right way?

[Lazulent]

The Tesla flow is a very attractive diagram but it ignores the essential fact that there is an inverter converting between PV/Battery DC and Grid/House(Load) AC. The inverter provides data in/out from each of these 4 sources. Trying to derive the Tesla Diagram's 6 notional flows from the 4 data points is a nonsense. We can't put a flag on every electron. Can't we please just add a pretty inverter into the centre of the Tesla flow and use the available real data. Power goes into the inverter, power comes out of the inverter. Much simpler.

[Adminius]

I would do it this way:
Add "losses intity" to PV and to Battery bubble.
You should have AC and DC Power from your inverter as an info.

PV_losses_entity: DC_production (-battery_charge)-AC_output => system losses with PV

Battery_losses_entity: Battery_Power(=DC)-AC_output= system losses with no PV power but DC battery

add each to the curresponded bubble and the values will be ok.

I have now added my systemlosses to the household load (yeah, not realy cool but it works) and now PV Production is ok (but household is higher...)

EDIT:
Better way is another approach:
User can provide values for pv and battery bubble as an extra entity, in this case no sum will/should be calculated