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Idea

Kevin Windrem suggested Apr 11, '20

Mode to give solar priority over grid

I have a system with Multi Compact 2000, 2400 WH LFP batteries, 4 100 watt solar panels and a 100/30 MPPT controller in my travel trailer. I would like a mode that gives priority to solar power over grid power. Currently, if grid is available, solar power is only used for DC loads or battery charging.

The ESS modes are close if the requirement to feed power back into the grid could be changed to an optional setting.

I'm reluctant to set the grid code to Other just to make ESS work because if I understand things correctly, this could allow some energy to feed back into the grid which isn't generally allowed here in the US.

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harold commented · Apr 11, 2020 at 07:43 PM

I think this is already possible, by ESS + not allowing the Multi to feed to the Grid (via VE Config

Harold

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Kevin Windrem harold commented · Apr 11, 2020 at 10:34 PM

When I set the Grid code to None, I can't start the ESS assistant. It reports an error saying it requires a country/grid code. So at least, the grid code needs to be set to something other than None which isn't recommended for mobile systems. Once this is done there are probably ways to tell the system not to feed power back to the grid. But something I read a while back (can't remember where) was that even set up that way there could be cases where energy feeds into the grid.

Another way to do this would be to provide an option in CCGX to prioritize solar energy over grid energy for both DC and AC loads. I believe DC loads are powered from solar energy before drawing from the grid but it's been a while since I played with it to be sure.

Giving solar priority over grid for AC loads is obviously not something the inverter/charger can do for itself since it has no direct knowledge of solar output.

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Daniël Boekel (Victron Energy Staff) commented Apr 12, '20

Hi @Kevin Windrem

one of the ways is:

https://www.victronenergy.com/live/assistants:ignore_ac_input_using_the_generator_assistant

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bigbadbob76 commented Dec 6, '21

As Kevin says, this would be a useful feature in venus.

For example I can set my Multiplus to inverter only mode (ignore ac -input) manually from the Multiplus settings menu in venus. it would be nice to have a setting to switch to invert-only if PV volts are greater than a configurable value. in my case this would be about 50V but each system will be different. It might need a time delay on switch on and off to prevent relay chatter.

I am well aware of the various ways to do this using assistants based on battery state of charge but this is a different approach that would be configurable remotely.

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bigbadbob76 commented Dec 7, '21

The only way I can see to prioritise DC PV usage is to drain the battery slightly.

This is because the MPPT is a battery charger not a power supply. it needs to see a battery voltage less than it's set point before it will load the PV panels. A battery with 100% SOC will throttle the MPPT output.

If AC-input is available then the Multi's charger will naturally take priority unless its charger set voltage is lower than the battery voltage at that instant, and/or it's input current limit is lower than the AC load demand.

So to prioritise solar we need to turn off ac input and/or disable charger and/or limit AC input current.

These settings are available manually in venus So I'll have a go at automating them depending on PV voltage but this might need a better programmer than me.

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bigbadbob76 commented Dec 16, '21

@kevin Windrem

As you know the gui files very well and have a lot of experience of them....

Can you tell me if this Visual item Model sets the mode of the Multi directly? or is there a .py file associated with setting it?

in PageVebus.qml-

model: VisualItemModel {

MbItemOptions {

description: qsTr("Switch")

bind: service.path("/Mode")

possibleValues: [

MbOption { description: qsTr("Off"); value: 4 },

MbOption { description: qsTr("Charger Only"); value: 1; readonly: !isMulti },

MbOption { description: qsTr("Inverter Only"); value: 2; readonly: !isMulti },

MbOption { description: qsTr("On"); value: 3 }

]

If this sets the multi's mode directly I can't add another option and value (5) as it won't be recognised by the multi, but if there is a .py in the way then this might be an option.

I'm trying a few things out and hope to get this mode working. :-)

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Mode to give solar priority over grid

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