question

jacques@ampo.co.za avatar image

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)
3 comments
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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.

jacques@ampo.co.za avatar image jacques@ampo.co.za Daniël Boekel (Victron Energy Staff) ♦♦ ·

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?

Rob Duthie avatar image Rob Duthie jacques@ampo.co.za ·

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.

1 Answer
Rob Duthie avatar image

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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