Hi All,
I've noticed a problem in a 45kVA ESS system recently installed. Here is the set-up:
- 3 x 15kVA Quattros
- 63kWh of Pylontech lithium-ion batteries
- CCGX
- Carlo Gavazzi EM24 with CTs
- 15kW & 10kW Fronius Symos on the AC in.
- All loads on AC out (Critical Loads)
System works well in general, however there appears to be a conflict happening on the days when the batteries reach the 15% minimum SOC:
At night, when the battery power has been used, the system correctly goes into #1 low SOC mode and draws no more power from the batteries, and pulls from the grid.
The problem is that the following morning, when enough PV power is available, it keeps throttling back the PV inverters to only match demand. So for example: when there is 10kW of solar available and 5kW of consumption with a 2kW grid set-point; it will only produce 3kW… instead of producing the full 10kW and start charging the batteries.
I can manually “kick-start” the system out of this dead-lock, simply by lowering the minimum SOC to 10% and restoring it 15%. The #1 state then disappears and the full 10kW is produced, charging the batteries in the process.
Having studied this over several days my theory is that there is a conflict occurring between the “phase compensation” in off-position and “zero feed-in” Fronius control.
Please note I have “no phase compensation” and “zero feed-in” set, because at the moment the system registration is being processed and no feed-in on any phase is recommended. I also have a conservative 2kW grid set-point to minimize momentary feed-in too.
My theory (and it’s only a theory) is that when low SOC #1 setting is functioning no more discharge of any type is allowed- this in effect, conflicts with the “no phase compensation”: it won’t discharge on any of the phases (good), but for some reason it won’t charge on any phases either (bad). It’s like it isolates the batteries from the system- neither charging nor discharging. The system throttles back the Fronius PV inverters in order to match Consumption minus grid set-point – instead of charging batteries with the excess solar available. And so the system stays stuck in low SOC, #1 until I kick-start it by clearing the #1 condition.
Does anyone have any explanation for this? Is this an issue Victron are aware of?
P.S. I’ve attached some screenshots: 2 of the ESS settings and 1 of the system in normal, correct operation- it hasn’t reached low SOC in the last week or so, so haven’t been able to capture that- but at least you can see how the system is set up.
