Control MPPT programatically for oversized solar system

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walter-widmore asked Mar 20, '22

Control MPPT programatically for oversized solar system

Hi all,

I currently have a decent working off-grid solar system (Multiplus, 2xMPPT, SmartShunt, Cerbo GX). I'm looking to add more solar because I have an electric car that is parked a lot during the day (when the sun is out).

The problem is that I'm already at my maximum solar array size because the battery can't handle any more Amps if the car would not be connected.

The solution that I can think of is to manually adjust the MPPTs battery charge current but of course I don't want to worry about doing this manually.

The car has an API so start/stop charging the car and even changing the charge Amps is no problem. The problem is I have no idea how to control the Victron equipment programatically.

2 questions:

1) Is there any way to control the MPPTs settings programatically either directly or by using the GX. (For example by connecting a Raspberry Pi which runs some logic)

2) Is there any way to read-out the Cerbo's data locally? For example, also by connecting a Raspberry Pi to it. (I'd prefer not to use the VRM API because I want it to work locally.)

Any starting points are more than welcome.

I'm perfectly comfortable in programming but not in talking to Victron hardware. Thanks!

cerbo gx api

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Answer 1 · 2022-03-20T12:10:57Z

Alexandra answered · Mar 20, 2022 at 12:10 PM

@walter_widmore

There is already a consideration in place for this kind of situation it is called DVCC.

I also have a lot of solar, I use the charge current limit in the DVCC menu to make sure my batteries don't get hammered, as they are not can bus managed; which is why I assume you have the shunt in place? (PS. notification in screenshot is my grid lost alarm - not a system problem)

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walter-widmore commented · Mar 20, 2022 at 03:40 PM

Hi Alexandra. This is great! Many thanks.

It brings up 2 follow-up questions.

1) I've set the charge current limit to 100A. When I disconnect a large load, the solar output drops from 4000W to 600W -> Charging at 20A in stead of the 100A I expected. Any idea why this is way less than it's supposed to?

2) I'm still interested in connecting a Raspberry Pi locally to the Cerbo as a read-only device so I can achieve the same for the loads: Start/stop large loads based on the solar and battery availability.

Many thanks

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