question

munga avatar image
munga asked

Fronius AC Coupled PV causing overcharging

I had a strange result today on a 2 x 5MP2 (10kVA) and 8.2kWp Fronius Primo with 9.99kWp (18 x 555Wp) panels. The system is connected to a Solar MD battery 14.3kWh.The problem was that the system continued to charge the battery even though it was at 100% causing the battery to charge to almost 58V. The BMS had parameters of CCL = 4A and CVL 52V yet it continued charging. Note this was not during a grid outage so not using FPSC to shift the power down.

Load demand on the inverter was about 200 - 300W.


The AC coupled Fronius is setup as ESS and per the Victron Guide. 1 : 1 (10kVA ( 5 + 5) : 8.2kW). Is it a problem with battery size?


untitled2.png


Modbus TCP power limit control

throttling.png

Battery Voltage and Current

battery-voltage.png


CCL, CVL and DCL

ccl-cvl-and-dcl.png


Multiplus-IIAC PV CouplingFronius
9 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

5 Answers
munga avatar image
munga answered ·

I answered my own question

https://community.victronenergy.com/questions/229608/charge-current-offset-with-parallel-multiplus-ii.html

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

munga avatar image
munga answered ·

ac-consumption-vs-pv-limit-vs-battery-voltage.png

You can see AC consumption is well below the limit of the throttling causing the battery to overcharge.


4 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

spatula avatar image
spatula answered ·

Hi Alexandra,

Thank you.

The installer will be fitting a Solar MD logger tomorrow to collect as much info as possible. I'll let you know what we find. Regarding the configuration the installer has done some thorough checking and I'll pass on your comments to them.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

munga avatar image
munga answered ·

My suspicion is that this overcharging is related to dual (parallel) multiplus-II install. It is almost as if the 2 inverters are both demanding power from the PV therefore doubling the required amount and hence overcharging this battery. Instead they should be each halving the demanded power.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

munga avatar image
munga answered ·

Anyone got some insight into this?

3 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.