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jacques avatar image
jacques asked

Multiplus II 3 phase ESS with Pylontech batteries - sometimes feed loads from grid while PV charge batteries

Installation consist of DC coupled 3 Phase system.

3xMultiPlus-II 48/3000/35-32 with Firmware 456

3xSmartSolar Charger MPPT 250/70 firmware v1.36, each 3.28kWp PV

3x Pylontech US300B - 10.5kWh battery bank

ET340 meter

Venus GX Firmare v2.42

ESS v2.42

Optimised without batterylife.

No Feed in

Minimum SOC = 70%

grid setpoint 70W


System works very well, except sometimes a condition occur where all PV goes into charging the battery although the SOC is higher than the Minimum SOC of 70% and all loads are powered from the grid.

Sometimes ESS indicates ESS#1 under this condition, bot not always. Two different scenarios below



Similar questions I found suggested it could be related to either the following, but none conclusive

1. firmware versions

2. ET340 meter functioning and VRM calc

3. phase compensation

4. Pylontech SOC inaccuracy


Any suggested ideas will be appreciated

Multiplus-IIESSPylontech
1580206351241.png (512.3 KiB)
1580206634262.png (41.4 KiB)
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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @jacques@ampo.co.za

in the second screenshot: L3 is using 4 kW, more than the L3 inverter can supply.

is phase compensation 'on'? and is feed-in allowed or not?

first screenshot: LOW SOC so that might be the reason.

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jacques avatar image jacques Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Thanks Daniël

Phase compensation is enabled. At the moment feed-in is blocked. We will change this in the near future, just waiting for approval by the utility

What puzzles me about the first screenshot is that the minimum SOC is set high at 70% as we currently have unstable grid in South Africa. The BMS indicate current SOC = 72%, which is above the minimum, why would ESS still indicate low SOC?

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Rob Duthie avatar image Rob Duthie jacques commented ·

Hi

Have checked the ESS setting? if it is set at 70% it will alarm out give or take a percent

So lower the setting down to 20% that way you can run for longer on batteries.

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3 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi

Have a similar system in single phase version.

SOC is to high it can go low as 15%, grid set point set to zero.

SOC is accurate.

Mine is set to feed in as well as we get a credit as well for excess generation in NZ

This is how i have set up my system, and the PV supplies the house loads first any spare goes into charging the battery, if the the house loads demands more the inverter will supply up to what ever setting you want up to 3kw, and if it can't supply, the grid supplies the rest.


Regards

Rob D

NZ

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mrjj avatar image mrjj commented ·

Hello, could you please tell how this is done?

"This is how i have set up my system, and the PV supplies the house loads first any spare goes into charging the battery, if the the house loads demands more the inverter will supply up to what ever setting you want up to 3kw, and if it can't supply, the grid supplies the rest."

I am aiming exactly the same. So is that done in Cerbo GX programming what controls and adjusts the charging power based on surplus of solar power ? I am about to buy a Multiplus II (GX?) 48V 3000VA and a Pylontech US3000C batterypack to start with.

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Rob Duthie avatar image Rob Duthie mrjj commented ·
Hi

This is correct you need the GX device to contol this for ESS mode.

Regards
Rob D

NZ

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lifeingalicia avatar image
lifeingalicia answered ·

Not sure but it looks like SOC may come from internal calculation not the bms of a bat. So small diferences to be expected. Would be interesting to switch VRM visibility to internal (multi) calculation.

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nickdb avatar image nickdb ♦♦ commented ·
If you hit the minimum SOC set in ESS, the system will charge it to 3-5% above minimum before stopping usage of grid for loads. It is how it works.
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Richard Weir avatar image
Richard Weir answered ·

I have set up a similar system with 2 x Multiplus connected to my Pylontech batteries, I’ve set up the system as a parallel system in Victron Connect but don’t seem to be able to fine VE Bus Quick config in order to reinstate the ESS battery / charging management. Any help would be gratefully received.

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