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alex-bush avatar image
alex-bush asked

MPPT Throttling with Multiplus II GX + SmartSolar MPPT

Hi All,


I have the following setup:

- Multiplus II GX

- SmartSolar MPPT VE.Can 150/100 rev2

- BMV-712 Smart

- 48V 200AH Lead acid battery bank


Firmware on all devices is at latest. ESS assistant is enabled. MPPT and BMV are attached to the MP2 via Ve.Direct cables over USB.

BMV is set as the system battery monitor.


I have a strange issue where the MPPT is stuck at 0W, even when the panels are insolated. Yet isolating the MPPT from the battery and reconnecting seems to clear this fault.


I will add that the MPPT seems to work absolutely fine in standalone mode.


Has anyone seen this before? Or can any folks from the Victron side shed some light?

Multiplus-IIMPPT ControllersBMV Battery Monitor
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alex-bush avatar image alex-bush commented ·
Just to add, I'm on the latest stable Venus OS image on the multi.
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alex-bush avatar image alex-bush commented ·

Bump? Any thoughts from the Victron side?

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3 Answers
nickdb avatar image
nickdb answered ·

You need to check the voltages, by meter, at the battery terminals and at the multi and the mppt and see if the voltages agree.

If there is voltage loss the mppt may be at a higher voltage to the battery which will cause it to go to sleep.

You can also test this by putting ESS into "keep batteries charged" mode. If the mppt wakes up, then voltage differences are contributing.

remember to give it a minute or so for changes to take affect.


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alex-bush avatar image alex-bush commented ·

Hi @nickdb


The readings in the UI on the MPPT and BMV both agree with the measured battery terminal voltages, as well as with the voltages present at the input of the devices.

I also tried "Keep Batteries Charged" but no dice.

If it is relevant, this always seems to happen after nighttime pretty consistently. (IE 8am, sun is up but 0W from the MPPT). For clarity, I'm located in the UK.

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nickdb avatar image nickdb ♦♦ alex-bush commented ·
The last comment seems to have vanished.

Check your PV voltage is at least 5V above the battery voltage, MPPT's don't turn on until you hit this threshold.

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alex-bush avatar image alex-bush nickdb ♦♦ commented ·
@nickdb PV voltage is 76V, Whilst the battery is sat at 51V.
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julyzin56 avatar image julyzin56 alex-bush commented ·

@alex-bush MPPTs switch on at this threshold.

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alex-bush avatar image alex-bush julyzin56 commented ·

@julyzin56 Which threshold? 76V for PV or 51V for battery? Can you point to this in the documentation?

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nickdb avatar image nickdb ♦♦ alex-bush commented ·
It would be at battery +5V so around 56V.

It's how all mppt's work, to compensate for the voltage drop under load.

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alex-bush avatar image alex-bush nickdb ♦♦ commented ·

@nickdb Correct, but I'm confused as to the purpose of @julyzin56's comment, Seeing as 76V is 15V above the battery voltage.

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nickdb avatar image
nickdb answered ·

Just confirm your mppt is under external control. Have you enabled DVCC?

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alex-bush avatar image alex-bush commented ·

@nickdb

Yep, MPPT is under Ext control. DVCC is enabled.

Charge current 20A limit

Charge Voltage 57.6V limit

SVS + SCS enabled.

SCS status showing "Disabled (External Control)

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alex-bush avatar image
alex-bush answered ·

Guessing there is _still_ no further info on this?

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