Grid independent ESS

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guydusautoy asked Mar 17, '21

Grid independent ESS

I have a multiplus ii 48/5000/70-50, DC PV array, Battery with built in BMS, MPPT and CCGX running ESS.

I want the system to run grid independent - using only PV and battery unless battery gets too low or load gets too high.

We have a very unstable AC input with large fluctuations of input voltage that result in regular inverter overloads and grid disconnects, even when the grid is available.

We have used the programmable relay assistants to prevent AC 2 out disconnect with the grid disconnections. (This is working well)

I want to use the Generator Start - Stop assistant to ignore AC input above a specified SOC and below a specified AC load. The point is to minimise exposure to the unstable grid input, but have it available when needed.

I have created the following config... not yet uploaded...

Will the assistants work together to give the outcome described above?

Is the order of the assistants correct?

Is there anything here that could cause damage to my system or electrical appliances connected to it?

Multiplus-II ESS BMS CCGX Color Control

screenshot-2021-03-17-at-214715.png (56.7 KiB)

screenshot-2021-03-17-at-214751.png (50.3 KiB)

screenshot-2021-03-17-at-214958.png (25.2 KiB)

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Modifications Space

Node Red Space

Answer 1 · 2021-03-20T12:58:13Z

Alexandra answered · Mar 20, 2021 at 12:58 PM

@guydusautoy

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/ess-introduction---features.html

You should probably remove the ess assistant then if you are wanting inverter priority.

The ac ingore overides all the useful features of the ess assistant and the system will ingore all the settings in that assistant. If you have a pv inverter use the pv assistant instead.

If you followed the instruction article and tweaked it for your system it should be good otherwise.

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

What are you using for soc? Need to make sure it is always accurate.

screenshot-20210320-145206.jpg (66.8 KiB)

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Answer 2 · 2021-03-20T13:21:20Z

porcini answered · Mar 20, 2021 at 01:21 PM

Hello guydusautoy,

unfortunately you totally misconfigured your unit. With an ESS installed (not designed for offgrid) a grid code must be set. I don't know which one you used, but it would have been much better not to use ESS. If you have the password remove the gride code and also the ESS.

Wide voltage and frequency range should be accepted, UPS function should be disabled. If you need the charger enable weak ac input. After that set an input current limit, enable power assist and dynamic current limiter.

To get the assistant working you have to OPEN the relay instead of closing it.

regards,

porcini

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Answer 3 · 2021-03-23T19:17:56Z

guydusautoy answered · Mar 23, 2021 at 07:17 PM

Thank you for the inputs. It is noted that ESS is not recommended for off grid or intentional islanding setups.

I would like to know what charging profile ESS uses during extended grid loss and how the solar and battery outputs are managed to meet the load.

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seb71 commented · Mar 23, 2021 at 10:14 PM

ESS manual.

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