question

mfred68 avatar image
mfred68 asked

Being off grid in ess mode

I noticed that while on grid in ess mode that I import and export quite a lot of energy, it sometimes jumps to several hundred watts at a time in both directions. My threashold is set to minus 30% and I've tried it at minus 50 and 60% but too much exports, if I go to -20% even more imports.

I've over sized my system to be more off grid than on grid.

I currently have 15kw of pv and 42kwh storage and a multiplus ii 10kva. We use around 15 to 20kwh a day.

I recently tried faking a grid power cut by turning off the grid breaker, and my system is working seamlessly as off grid with an ess configuration for 4 days now, this includes my enphase microinverter panels, they also still work off grid. (My enphase did not produce when I previously configured my system as off grid, not ess)

So here's my question. I want to keep my system running in this off grid mode in ess configuration, but if the batteries reach 100% or fall below 20% I want the grid to reconnect to export and import respectively.

Can the relay on the cerbo gx be used to switch a contactor in line with the grid supply on and off when the batteries reach a programmable soc? Or can this only be done with the multiplus relay?

Reason I'm asking if the cerbo gx relay can do this is because I need to use the multiplus relay to switch a different contactor for hot water at a certain soc.

Also is it damaging using ess mode with the grid disconnected? Just in case

ess settingsgateway relaygrid relay
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1 Answer
nickdb avatar image
nickdb answered ·

I have been connected for 3 days of the last 4 months, that isn't an issue.

You can use node red to flip the inverter soft switch to invert only and back to on as required by SOC, really easy to do.

There are less flexible ways of doing this with assistants, relays etc, but nodered is easiest imo.

This would be a topic for modifications section however.

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mfred68 avatar image mfred68 commented ·
This node red switching sounds interesting, though not sure how to do this. Where di I start, any instructions would be really helpful
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nickdb avatar image nickdb ♦♦ mfred68 commented ·
Go look on yootoob for the victron node red beginners tutorials. This will plant the seeds.

From there, the modifications section (old forum) is a wealth of ideas. It isn't that difficult, just requires some fiddling.

Once you are comfortable that you are suitably dangerous, post any questions on the new modifications forum. A lot of knowledgeable folks there who can help steer.

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mfred68 avatar image mfred68 nickdb ♦♦ commented ·
Thanks I'll do exactly what you suggested, this could be the answer.
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Alexandra avatar image Alexandra ♦ mfred68 commented ·
@mfred68

If learning to make flows is not in your interests or fast enough, you can adapt this older article.

https://www.victronenergy.com/live/drafts:acin_ignore_timer_using_ccgx_gen_start_stop_example

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