DC-Coupled Feed-in: Multiplus II is limiting PV power

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puntasso asked Jul 15, '22

DC-Coupled Feed-in: Multiplus II is limiting PV power

Hello,

The system is:

- Multiplus II 48V 5000VA 70/50

- 2 x US3000C Pylontech.

- Cerbo GX.

- 5.2kW PV in DC-coupled with:

- 4 x SmartSolar MPPT 150/45 (2 with 4 pannels and 2 with 2 pannels)

The problem/issue:

- All is working fine, but when battery is charged the max power feeded to grid from PV is 3600W so there is wasted energy from PV. It seems like inverter is trying to keep production at 74Ah (DCL from CAN BMS).

My question:

- Is the Multiplus limiting the max power to feed grid at DCL parameter from CAN BMS although the energy is coming from PV field and not from battery? What can I do to feed grid with all the PV field power?

Thanks.

Edit:

- All MPPT are working together and controled by Cerbo GX by BMS (DVCC enabled). Charge Voltage (42.8v) and Charge Current (45A each) are setted at maximum by Cerbo, so the MPPT are no limiting, is limiting the Multiplus Inverter.

Multiplus-II Pylontech feed-in limit

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Answer 1 · 2022-07-15T23:35:34Z

matt1309 answered · Jul 15, 2022 at 11:35 PM

Guessing you've already checked but there's not a grid feed in limit set in ESS is there?

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puntasso commented · Jul 16, 2022 at 12:44 PM

Yes, of course. No grid feed-in limit, and I tried setting the limit to 5500W and no change.

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Answer 2 · 2022-07-16T11:43:55Z

puntasso answered · Jul 16, 2022 at 11:43 AM

Today I tried to charge the battery at 12:30PM:

- PV is at 84% total installed power (T=40C). Working perfect.

- Battery is charging (Initial SOC 42%). So "bulk state"?

- ESS Mode: Optimized without battery life.

In this situation I set "grid setpoint" to 3700W and the inveter is feeding grid at a rate of 87A DC (Dc/Vebus/Current), so it seems like when battery is in "bulk stage" the inverter is no limiting at DCL (74A).

So, maybe the inverter cuts the max power to grid and loads at DCL when the battery is in "absortion stage"?

captura.png (62.4 KiB)

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puntasso commented · Jul 16, 2022 at 12:52 PM

And now, when battery is chraged (more than 99% SOC).

It takes a few minutes and voltage on Multiplus increase to 52.7V from 52.4V, and current consumption from inverter to feed grid is mantained at +-74A (same as DCL). So all PV power is not used because the inverter itself is limiting the DC to AC feeding at DCL, though it is not draining from battery.

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captura2.png (54.0 KiB)

Answer 3 · 2022-07-22T22:27:50Z

smart-home answered · Jul 22, 2022 at 10:27 PM

I’ve also been looking for a solution to this issue!

The last thing I tried which I think has fixed it is as follows:

Connect to your MPPT charger using Victron Connect via bluetooth and check settings.

I found the voltage levels were set lower than recommended in the Victron/BYD document (see section 6.1 in screenshot). Therefore I believe the charger itself was throttling back when the battery was full due to the higher voltage.

My battery is a BYD, but maybe Victron have recommended settings for your battery too.

138d86ef-ceb4-4514-89c5-d506077a59bd.png (518.5 KiB)

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