mpvader
commented
5 months ago What is the status of this Izak? On the todo it says this:
-
Fix problem where batteries are not charged at full speed, while there is ample PV from a PV-inverter
- This is done by adding a new setting for increasing the PV-inverter offset.
- This offset is used to handicap the Multi, to ensure that the PV-inverter has priority. If the offset is too small, it can get locked up at a non-optimal point.
- This is an addition to the improvement made in Venus 2.60, where this offset is always least 2% of the total PV-inverter capacity.
- In most systems it is not necessary to change this. It is added only because other options have been exhausted.
- https://github.com/victronenergy/venus/issues/1175
Was anything actually changed for users? or was just a new setting introduced, but not to the gui, so nothing fixed or changed for users yet?
In case that last is what the situation is: lets leave it at that then and finalise this in v3.30
Todo
Background
In a system with both a Multi/Quattro and PV inverters, and where grid feed-in is limited, there is a possibility that the PV-inverter and the Multi competes to reach the ESS grid setpoint.
Once the setpoint is reached, a state of equilibrium results where the PV-inverter can not ramp up any further. If this state happens in a place where the Multi carries more of the load, or doesn't charge at full speed, you end up in a deadlock where PV is not fully utilised.
For this reason, hub4control has for years had an offset, where it will raise the PV-inverter setpoint by some amount whenever there is a PV-inverter that is in running state, so that the PV-inverter will always aim slightly lower than the Multi. This creates a tug-of-war (touwtrekkerij) around the setpoint, and favours the PV-inverter.
This mechanism was later enhanced, and instead of using a hardcoded offset, it was made to be 2% of the PV-inverter capacity. That way it scales with the PV-inverter size.
The offset cannot be made too large. If it is made too large, the Multi will have a tendency to import too much from the grid during the day.
Problem
We STILL have sites where the offset just isn't large enough, and a non-optimal equilibrium arises at times. As stated before, a larger offset will cause more grid import, and a smaller offset creates more chance of non-optimal equilibrium.
Suggested solution
Make the offset configurable. I'm generally not in favour of having too many configurable options, but this bug doesn't lend itself to many more options.
TODO