ESS does not provide PV power to loads

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nhenderson asked Apr 26, '21

ESS does not provide PV power to loads

We have a CCGX, MPPT with 12x270Wp panels, 6x Pylontech 3000C 48v batteries, and a Multiplus 5000/48/70. ESS is set to "keep batteries charged" because, we have frequent and sometimes lengthy grid outages and the main priority is to keep power on throughout those outages.

The CCGX is programmed to start a generator at 20% battery SOC. The generator is connected via an automatic transfer switch which means that the overall Victron system only sees AC power without knowing the origin.

If there is no AC power the system performs as expected: PV supplies loads and also charges the batteries to the extent it can.

If there IS AC power and the batteries are < 100% the system performs as expected: PV supplies what it can to loads AND batteries, and the AC input fills in the slack.

If there IS AC power and the batteries are full then we go off the rails. PV supplies nothing and the AC input supplies 100% of the loads.

What this means is we are paying the electricity company whilst solar power goes unused.

I am able to fix this by enabling grid-feed-in, even with a limitation of 0W. Then, the PV supplies all that it can to loads (or battery charging) and AC input takes up the slack.

However: our country has no arrangements for grid feed-in and I am not sure whether the prepaid meter will tolerate it, or be damaged. (I have set grid code Other)

1) Does grid feed-in with a limitation of 0W guarantee no power goes to the grid?

2) With grid feed-in disabled, surely ESS should prioritize PV in ALL situations to power loads as well as charge batteries? Surely that is the most normal use-case: one wants to use solar power, in any situation, before buying energy?

3) Should I be reporting this as a bug in either the ESS assistant, or the Multiplus firmware, or the CCGX ESS implementation?

ESS

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Answer 1 · 2021-04-30T19:46:36Z

Alexandra answered · Apr 30, 2021 at 07:46 PM

@nhenderson@ceml.net

I think your issue is specific to your setup. So it must be setting related. Grid feed in is not allowed here unless you have a special connection so i can relate, we also use grid code other.

What is your grid set point? We have found to prevent feedback we pull a bit from the grid like about 100w or 200W (you may need to experiment) and also to use the pv more this setting helps.

Also feeding back to grid option is not enabled at all - it should not feed in but i have seen in some systems there can from time get an overshoot when a load drops off in the property.

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/configuration.html#UUID-d5ba0921-8b24-03ea-5400-f17704a4071c

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Answer 2 · 2021-04-30T20:56:14Z

nhenderson answered · Apr 30, 2021 at 08:56 PM

The only solution I found works is to set ESS to feed in to Grid, but, limited to 0W. That takes care of the PV providing all it can before grid power is used for loads with batteries full.

When the grid is down there is no problem because we have an external contactor that disconnects so there could not be any feedback for example if the utility was shut off deliberately for maintenance.

When the grid is up I expect the minor loads that are on the outside of our system - a battery charger for the generator and a few other small items - provide enough bias to prevent actual feed-in given the 0W nominal limit.

I will be monitoring to see if this actually works out.

I do think that Victron should have an explicit configuration option to prefer PV over grid, not only for battery charging, but for loads. Preventing grid usage as much as possible is an obvious use case.

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Alexandra ♦ commented · May 01, 2021 at 12:05 PM

There is if ess if programmed and sized correctly. All my installs of ess provide power during the day from pv and only pull from the grid at night with the minimum soc of the battery is reached. This is an example from a person who keeps their batteries fully charge in case of grid faliure.

See the grid useage graph below.

The draw from the grid is at grid set point during the day when there is sun.

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screenshot-20210501-140412.jpg (127.7 KiB)

Answer 3 · 2021-05-01T12:49:42Z

nickdb answered · May 01, 2021 at 12:49 PM

There is a bug with ESS and pylon. I've seen it on two installs.

If you enable scheduling with ESS then PV is badly clamped.

Disable it and it works.

There is something with the two that don't play nicely together.

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Answer 4 · 2021-05-01T17:11:29Z

nhenderson answered · May 01, 2021 at 05:11 PM

Thank you Alexandra. I'm not sure what is "self-consumption", the links I saw suggest it relates to one of the pre-ESS "Hub" assistants. We are on ESS "Keep Batteries Charged" because we have frequent grid outages of varying durations, which occasionally could go for days (in which case we have set up the CCGX relay for the generator to start and supply "grid" once the batteries reach their minimum threshold).

There is no "grid set point" option anywhere in our CCGX settings nor Multi settings.

Our current strategy is working fine for now, Feed-in DC PV enabled, limited to 0W.

I say again, VICTRON should implement an explicit option to allow PV power to both feed loads and charge batteries, in preference to available grid power as much as able, and NEVER feed-in to the grid. It's an obvious use case and we should not have to be experimenting with "tricks".

Victron staff please respond...

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Alexandra ♦ commented · May 01, 2021 at 06:20 PM

@nhenderson@ceml.net

In the ess menu on the ccgx, just above the feed in options, is the grid set point.

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Answer 5 · 2021-05-02T14:39:00Z

nhenderson answered · May 02, 2021 at 02:39 PM

@Alexandra I see what you mean. Grid setpoint only appears if the ESS mode is "Optimized" with or without battery life. I am using "Keep Batteries Charged" ESS mode. Anyway everything is now working the way I wanted.

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Alexandra ♦ commented · May 03, 2021 at 06:51 AM

That is good to hear, You can set the battery percentage to 100% with the optimised with battery life and have the pv working for you a bit better. If you allow 95% it will also work the pv a bit more. It is where I usually hover the SOC for ESS systems who want as much battery as possible. The Optimized with battery life will then make sure the batteries do get to 100% during the day when you have enough solar for loads and charging.

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