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Topic starter
October 23, 2024 4:03 pm
I wanted a place in this Forum for EG4 users with AC coupled PV systems to compare notes. If this discussion belongs elsewhere, somebody let me know and I'll try again.
I have 20 Panasonic Evervolt panels with Enpase IQ8 microinverters connected to an EG4 15K inverter and a outdoor wallmount 280AH battery - installed indoors. The system was commissioned only a few weeks ago, so I've not had much experience with it. A couple of oddities I'm wondering about are:
- I have AC Charge enabled with the Start AC Charge SOC% at the default value of 90. The inverter seemed to disregard the setting and started recharging at 95%. I lowered the AC Charge Stop SOC% to 85% and the AC Charge Start SOC % to 75%, and the inverter started recharging at 80%. Happily, it did stop at 85%. The inverter seems to think that a 5% discharge is enough to trigger a recharge. I don't particularly care about the charge starting point, but it seems odd that the setting would just be ignored.
- When testing with the grid disconnected a while back, I noticed there was a period when the power flow image on the inverter's little screen showed power flowing from the inverter to the EPS. But I don't have any EPS connected to the system, and why would it send power to it if I did?
Has anybody else experienced either of these situations? Is your AC Coupled system running perfectly? Or if not, what's up?
Topic starter
November 17, 2024 11:48 pm
Tristan again. Since my last post, I've learned from EG4 support that having the power flow image show power going to the EPS icon when off grid is normal - even when you don't have an EPS. Coulda fooled me.
But I'm still having trouble getting the charging to work as I think it should. Could anybody clarify the role of the various charging parameters for on grid and off grid operation?:
- System Charge SOC Limit
- Start AC Charge SOC
- Stop AC Charge SOC
- AC Couple Start SOC
- AC Couple Stop SOC
On my system, when on grid, it still looks like the start values are ignored. That's OK, but I would like to at least understand how the Limit and Stop values are selected for both on and off grid. I suspect this would be useful for other AC Coupled users as well.
November 18, 2024 7:59 pm
The System Charge SOC limit refers to the maximum allowable state of charge for the system. The Start and Stop AC Charge SOC settings define when the AC input will begin charging the batteries and when it will stop.
Below is an example using 80% start and 99% end SOC:
-
When Battery Capacity is Higher than Start SOC (80%)
- AC coupling will not operate.
-
When SOC Reaches 100%
- AC coupling will cease to operate.
-
When PV System's Energy Production is Insufficient
- The battery system collaborates to share the load.
-
When Total PV Energy Production Exceeds Battery Charging and Load Requirements
- The existing inverter initiates over frequency derating and MPPT perturbation to balance the overall system's power consumption
November 18, 2024 8:00 pm
Also, if frequency shifting is needed, I would recommend having the AC couple start SOC set in the range of 95-99% with the ending SOC set to 100%.
Topic starter
November 19, 2024 12:28 am
Thanks Jared. But just to clarify:
In example 1 where you wrote "AC coupling will not operate." I think you meant "AC charging will not operate". Same thing for example 2.
And I think both of these examples refer to the AC Charge Start and Stop that are included in the "Charging" section of settings on the Monitor web site. I'm guessing that these settings can only apply when GRID AC is available, right? The fact that solar AC is available isn't relevant.
On my system, I have the System Charge SOC limit set to 85%, the AC Charge Start at 75%, and the Stop at 85%. The system starts charging at 80% and charges up to the 85% stopping point. It ignores the 75% Start setting. That's why I'm a bit confused about how these setting are supposed to work.
But the rest of my original question was how the AC Couple Start (and Stop) SOC work. These are the settings in the AC Couple section of the Monitor website. Do these settings only apply ONLY when off grid, and when there is excess solar AC available?
In keeping with your recommendation, and my preference not to fully charge the battery while it's not being used, I have the Stop set at 85% and the Start at 84%. Is that OK?
Were there to be an exetended grid outage, I'd raise them to the 99% and 100% that is recommended.
