I have following system:
3 x 48/5000 VA Multiplus II as 3-phase system
1120 Ah battery bank
MPPT 450/100 + 6,9KWp panels
ESS assistant on all inverters, no other assistants installed
Connected to Grid (code: Europe EN50549:1)
Mode : Optimized without battery life
MP II settings: Grid current Limit: 20A
Battery:
CVL: 56V
CCL: 475A
DCL: 475A
ESS settings:
Grid setpoint 0W
Grid feed in 12kW
AC&DCcoupled PV feed-in excess: Yes/Yes
I also updated Firmware to the latest:
Gerbo Fw 3.51
MP II: Fw 552
Issue is with impaired battery charge rate.
System could feed-in to Grid the rate I set (12kW in is this case) - no problem here using DESS.
However, the battery charging is somewhat throttled to max 8-9kW (which is about 13A per Multiplus).
I want to charge with maximum available power (ca 13kW ) during cheap tariff period, but I could not figure how it is achieved. I used ESS scheduled charging, DESS on and off - still not the max potential of inverter.
I had the system running quite a long time without ESS and the system was able to charge the batteries with max 19-20A/ 13kW without a problem (I used AC ignore feature with generator start/stop relay function).
I’ve searched trough the forums but haven’t found whether this is “normal” behavior when using ESS. How could I utilize the max potential charging current of the inverter?
Your Grid current limit is set to 20A…maybe there are other AC loads active?
Besides, the max. you could expect is 3x70A according to charger specs on the DC side.
Maybe your BMS is limiting the charge current (typical when temperature is too low or too high).
When ESS mode set to “keep batteries charged”…what is the load you see?
My system, although reporting 370A allowed from the BMS will “only” charge with 190-198A (~9.8kW) which is near the max of 210A (rated at 25°C).
I tried “Keep Batteries charged”
To be more specific:
ca 9 kW is all power that is coming from Grid. This includes battery charging + any AC load. Therefore to battery goes even less. As I mentioned - in case of no ESS assistant applied I could draw 12 kW without any throttling.
Below are 2 screenshots:
-
System squeezed 9,8 kW including 3,4kW AC load. I understand that in this case L2 is near to limit and it is what it is. DC side 111A
-
3 minutes later I disabled large AC loads and I get still get the same 115A on DC side. 7,1kW from Grid. Ambient temp is 20C.
The reason I asked the question - without ESS assistant I could draw much more power from the Grid to charge the battery compared with permanent ESS grid connection.
Maybe you are mixing input/charge-max current and max Output?
3x4kW = 12 kW is the max output = discharge Power of the MP-II 48/5000
12 kW charge Power is equal to 3x70 A at 57V DC, which seems a bit high of a voltage or am I wrong?
As another resort, try and disable peak shaving in ESS…does that help?
That feature has been introduced a couple of versions back.
Thank you for the pointers.
I sure mixed up inverting and charging capabilities.
Looking back to old stats before ESS configuration I see that I’m in the same ballpark concerning max battery charging power. Multiplus derates the charging power as its internals warm up. In the following screenshot I see declining power as charging progresses:
Case closed.
Yes, if you want to charge most efficiently, aim for ~85Amps in a 3phase system.
Somewhere, at least in the old forum, the efficiency diagrams were posted.
