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createchpl asked

ESS - feeding-in all PV power to grid, but not charging batteries

Hi, I have commisioned a new ESS system containing:

- 3x Quattro 48/15000

- 4x MPPT RS 48/200

- 1700Ah of LiFePo4 with CAN-BMS

- 2x Fronius Symo (20 + 17)

All AC-loads and PV inverters are connected on AC-out 1 and there is no Energy Meter in the system. Minimum SOC is set to 30% and AC and DC feed-in are enabled. ESS mode: Optimised without Battery Life. Of course all firmwares are up to date.

My problem is that when there is plenty of PV power available, and the batteries are at Minimum SOC after night, it feeds all the AC PV to the loads and the grid. It also limits the DC PV to around 250W and does not charge the batteries, so after all day they sit at 30% :/

Only thing that temporarly helps is to set feed-in limit to 200W, then Solar Chargers start to charge batteries.

Is it a known bug or just normal system behavior? I am looking forward to any advices.

ESSAC PV Coupling
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Alexandra avatar image Alexandra ♦ commented ·
@createch.pl

Does it change if you switch to with battery life instead of without?

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createchpl avatar image createchpl Alexandra ♦ commented ·
It doesn’t change a thing. It also doesn’t matter if the DC Feed-in is enabled or not.
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3 Answers
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matt1309 answered ·

Sounds odd to me, I've not heard of this happening before.

Do the Fronius also ramp down output or is it just the DC coupled PV?

My first guess was going to be some extremely low current limit set within Quatro settings or in DVCC but that doesn't explain why it works when the grid limit is dropped.

What happens if you increase the minimum SoC or set to keep batteries fully charged. Does the system then push all the power in the batteries. Just to confirm that it is able to charge the battery.

Any warnings/errors coming from BMS?

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createchpl avatar image
createchpl answered ·

f040d801-951b-4ed8-afb2-e0d4a22853cd.jpegYes it is odd. When in „Keep batteries charged” mode is directs power to the batteries, and powers the loads. Excess power is then feed to the grid. DVCC settings are default for ESS. BMS alows charging and discharging, so everything seems to be ok, except not charging issue.

As shown on the screenshot, the little bump in SOC is when I changed the feed-in limit to 200W


f040d801-951b-4ed8-afb2-e0d4a22853cd.jpeg (225.6 KiB)
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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @createch.pl

CANbus connected battery?

have you tried DVCC with / without SVS?


have you measured voltage @MPPT terminals vs Quattro / Batery terminals? (what is the V-drop?)


what length / size wiring and how are things connected?

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