ESS Critical Loads vs Grid paralleled

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matt1309 asked May 4, '23

ESS Critical Loads vs Grid paralleled

Hi Folks,

I'm looking to upgrade my system so that my loads are all Critical loads on ACOut1, rather than my current setup being Grid paralleled on ACIN.

With my current setup I have ET112 and I experience a lag/delay, ie load of 2kw turn on takes a few seconds for ET112/ESS to ramp up to cover the load and vice versa when load turns off. I'm curious if this behaviour still occurs if loads are on ACOut1? I'm looking to get grid usage to literally 0. Or is the only solution to achieving that turning off the grid input? (I'm reluctant to go that route as I may want to charge from overnight in the winter. I suppose I could get some sort of remote controlled relay for grid input but seems to add complexity which i was hoping to not require).

ESS offgrid acout

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Modifications Space

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Answer 1 · 2023-05-04T09:24:03Z

nickdb answered · May 04, 2023 at 09:24 AM

You will never get to 0 with ESS, there is always power moving in and out, unless you use AC ignore to disconnect.

Best I can get to is 0.3kWh per day.

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Answer 2 · 2023-05-04T09:24:45Z

sharpener answered · May 04, 2023 at 09:24 AM

I have a Multi-II-GX 5k with all loads on AC-Out 1, and using the internal current sensors there is no noticeable delay in following changes in load.

With the grid setpoint = -20W the grid consumption is very small but as @nickdb says you will never get it absolutely to zero.

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Answer 3 · 2023-05-04T10:40:14Z

matt1309 answered · May 04, 2023 at 10:40 AM

Cheers guys.

At the moment my plan is to have all loads on ACOut1. As was hoping like you said @sharpener that the internal CT would be instant in comparison to ET112.

However in the future if my loads get too large I suspect I'll reintroduce some loads on ACIN side so need the Et112 again which seems like it will go back to the lagged version (hopefully by then the fast meters will be more affordable).

Sounds like internal CT makes it a fair bit better but not perfect.

Thanks @nickdb I'll have to have a read up on AC ignore, I'm guessing that's a VeConfig setting. I had a quick search and looks like I can set it to come on when certain load is reached. I thought this would be the ideal solution if it had a time/schedule feature as well but thinking about it I'm probably just trying to reinvent ESS then. The only difference being it physically disconnects grid when sufficient solar/load is manageable by inverter without any passthrough. Might look into a chunky relay and use node red to switch grid input and have that turn on when in absorption and at night when i want to scheduled charge. At least then I keep ESS features

Thanks guys!

6

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nickdb ♦♦ commented · May 04, 2023 at 03:04 PM

You can actually set it up quite easily with the victron connect app - it's called conditional AC access. Poke around in demo mode, you can see the metrics it can use to trigger grid usage.

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matt1309 nickdb ♦♦ commented · May 05, 2023 at 11:40 AM

I've had a little dig around in victron connect. Dont suppose you know if this can be controlled via dbus path/MQTT or modbus.

I might be worth me looking into making my own replacement for ESS assistant using these settings. Ideally I'd have ESS features (scheduling charging etc) but also with the AC input turned off outside of scheduled times or peak loads but i thought i'd read somewhere that you cant have both at once?

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sharpener commented · May 04, 2023 at 03:58 PM

The Victron external current transformer accessory is said to react much faster than the ET112, though I appreciate you have got that already. But there are equivalent CTs available on Amazon quite cheaply, somewhere on here there is a link.

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matt1309 sharpener commented · May 05, 2023 at 11:34 AM

Thanks @sharpener

I would go CT route unfortunately in current setup (main reason it's setup this way) is the grid input to the property is circ 80m from the multiplus. I assumed ct signal would not survive that run.

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sharpener matt1309 commented · May 05, 2023 at 01:26 PM

CT signals are surprisingly robust. I have got a harvi with the CT connected via 2 spare cores in 20m of an unscreened cable originally installed for my rainwater system. Other people have succesfully reported longer runs with both myenergi and Victron systems so I would think it is worth a try esp with a cheapo CT. The source impedance is low and the signal is only 50Hz so not demanding much bandwidth, I would go for twisted pair and keep it away from mains wiring if poss. No more of a problem than connecting an ET112 over 80m of cable.

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matt1309 sharpener commented · May 05, 2023 at 02:18 PM

Thanks @sharpener i didnt realise it would survive a run of that length.

I'll chuck another cat6 down when i put my new wire in (for when i change to using ACout rather than ACIN, see if that makes things better) I just assumed ct wouldnt handle the run.

Atm i only have one cat6 run and need that for internet (I'm using RS485 to TCP/ip to get et112 data down to multiplus). Planned on running another cat6 so i no longer need the rs485 to tcp adapters but might just use it for CT. Would be a nice solution if that works

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Answer 4 · 2023-05-05T15:33:36Z

dj-dulux answered · May 05, 2023 at 03:33 PM

I have been monitoring my on Vs off peak usage. Overall I get 98% running on off peak, so during the day I lose the 2% due to the slow response. I am ok with this, seems pretty good to me.

Dupe...

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