question

roblatour avatar image
roblatour asked

What happens with 'ESS - Feed-in excess solar charger power' set to off?

The documentation here: https://www.victronenergy.com/media/pg/Energy_Storage_System/en/configuration.html

says:

"4.3.5. Feed-in excess solar charger power

Set to 'On' to make the solar charger always operate at its maximum power point. The first priority is powering the loads, and the second priority is to charge the battery. If more power is available when those two priorities are met, then that power will be fed to the utility grid.

Please note that when enabling this option, the DVCC charge current limit configured under Settings → Limit charge current won't be active. The solar charger will operate at full power for maximum feed-in into the grid. It's advisable to configure a safe limit on the solar chargers when used with a small battery bank."


but it does not say what happens when this value is set to 'Off'. What happens when the option is set to off?

I know I don't want it on, as I only want to feed into my home wiring, but it is unclear if this will still happen if this value is disabled.


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2 Answers
ejrossouw avatar image
ejrossouw answered ·

@RobLatour If you have a Victron system with MPPTs then only the household loads will be served once the batteries are charged and the grid setpoint maintained.

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roblatour avatar image
roblatour answered ·

@ejrossouw thank you that was helpful.


But for clarity, the document says

"

4.3.12. Grid setpoint

This sets the point at which power is taken from the grid when the installation is in self-consumption mode. Setting this value slightly above 0W prevents the system from feeding back power to the grid when there is a bit of over-shoot in the regulation. The default value is therefore 50W - but should be set to a higher value on large systems.

"

so if "Feed-in excess solar charge power" is set to off, and the grid set point is at its default of 50W, does that mean that power will NOT go to the grid.from my small system (described here: https://community.victronenergy.com/questions/289698/ess-setup-to-power-home-but-not-feed-into-grid.html ) (which is what I want) regardless of the SOC of the battery or how much power is available from the Victron MPPT (fed by my solar panels)?


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ejrossouw avatar image ejrossouw commented ·
Correct. It allows you to manage the power distribution to the house loads between the grid and system as required.
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nickdb avatar image nickdb ♦♦ commented ·
The inverter is synced to the grid, this requires some form of power moving to/from the grid.

The setpoint is a nominal value that the ESS strives to maintain. Default is 50W, many set it lower to get as close to 0 as possible.

Others use it to force feed-in, outside the standard mechanisms, by using a negative value.

Power is always ebbing and flowing to/from grid as loads transition, this is the nature of electricity and low-frequency inverters, but it is not feeding-in as regulators would define it.

You can also use the "ignore AC" option to completely disconnect from grid based on various system parameters.

Dig around with the search feature, there are many existing topics that discuss all this in great detail.

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roblatour avatar image roblatour nickdb ♦♦ commented ·

@ejrossouw@nickdb Thanks very much, your responses have been very helpful.

Of note, just for the record, I am not posting here out of laziness - I have been doing quite a bit of searching and video watching already. However with the search, when I enter the search terms I'm interested in I often get 10,000 results returned :-) and when I wade thru the top results while I often come upon interesting information sadly much of it is irrelevant to my use case. The same for the videos - 15 to 30 minutes can yield only a few moments of new / related info :-).

In my case I really am not interested in feeding into the grid at all, in fact want to actively avoid it, so setting this value to 0 would on the surface make sense but it seems it needs to go a little higher (50W .. 10W) to actually do what its is generally intended to accomplish.

So I really do appreciate the feedback here - thanks again.

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ejrossouw avatar image ejrossouw roblatour commented ·
To add to what nickdb said, when you sync with the grid, you are "feedin into the grid" for all intents and purposes, but use the grid setpoint to only feed enough to serve the household loads if set at 0. (It is much like running with a bowl of water and trying to stop it from spilling over.) If it is set at e.g. a negative value of -100, ESS also uses storage to maintain that -100, whereas with the excess solar setting, ESS will only feed in excess solar when available.
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