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Jim Ryan avatar image
Jim Ryan asked

Zero Export For DC Coupled System with Cerbo GX

I am designing a grid-connected, self-consumption, DC-coupled system with the following components:
- Cerbo GX
- two Quattro inverters
- SmartSolar MPPT Can charge controllers
- Miasole CIGS thin-film ‘Flex modules’
- LFP batteries with BMS and closed-loop communications

But NO FRONIUS INVERTER or other AC-coupled inverter....simple DC-coupled with Victron components.
My question is, can the system as described above be configured to provide Zero Export to the grid, ie after loads are satisfied and batteries are fully charged? Can the Cerbo GX and ESS provide reliable zero export?

After reading and re-reading the ESS Design and Installation Manual it’s very clear how an AC-coupled system can work to provide zero export.....but it is much less clear about a DC coupled system. It suggests it can provide zero export, even without the addition of a separate AC grid meter, but it does not say that explicitly. I need to know if the Cerbo GX can handle this, ie provide zero export or grid feed-in, as I really don’t want to have to buy and integrate a separate third-party zero export device.
Thank you Community...
Jim

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Jim Ryan,

Yes, this works as expected.

There is a menu on the GX device called ESS, and there you can enable or disable grid feed-in for AC and DC solar independently.

In this screenshot the DC-coupled PV feed in excess is enabled, but you would want to disable it;

cleanshot-2023-03-06-at-150424.jpg


cleanshot-2023-03-06-at-150424.jpg (83.9 KiB)
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Jim Ryan avatar image Jim Ryan commented ·
Thank you Guy....I enjoy your videos...nice to see your prompt response.

FYI, the grid feed-in is split-phase, 225 amps, so I will need a separate grid meter (EMS24) with CT's to provide meter data to the Cerbo GX, especially as my two Quattros do not receive all AC input from the grid.
I think I understand how to do this now....although I must say, the ESS Design and Installation Manual seems very 'slanted' toward AC-coupled info while the DC-coupled part is confusing. In my opinion anyway, after reading and re-reading half a dozen times.
Thank you again.....
Jim

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clay123 avatar image clay123 commented ·

Hi @Guy Stewart (Victron Community Manager) ,


I have a similar situation with my dc coupled system - the system consists of:

- 2 x smart solar RS450/200

- 6 x Multiplus ii 48/5000 (2 per phase)

- CCGX

- BYD batteries


System is connected to the grid for battery charging but I do not want to export any power into the grid. If I disable the DC-coupled PV feed-in excess would it solve this ? Or will there be a bit of export still ?

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