question

philippe avatar image
philippe asked

ESS with grid feed in and AC input ignore

Maybe I interpret something completely wrong or there is room for improvement with AC input 1 ignore.

Configuration:

  • Venus GX V2.84
  • MultiPlus Compact 12/800/35-16 product id 2603 firmware 492
  • BMV-712 Smart V4.08
  • SmartSolar Charger MPPT 150/35 V1.59
  • LiFePO4 Battery 12,8V/1601h Smart
  • VE.Bus BMS
  • VE.BUS Smart dongle
  • Solar panel (3) 175W-12V Mono (serial connection)

With LiFePO it is recommended to configure ESS with Battery Life. I want to feed in the grid my excess DC PV power. Also I want to ignore the AC input except on load (>750W), low voltage (<12,80V) or low SOC (<30%). Also disconnect the AC input after Absorption.

Why the AC input 1 ignore, because he drains the load from the grid and keep the battery at 100%.

The issue I have is that due to the AC input ignore, the grid feed in does not work.
I noticed this yesterday as overnight the battery has been charged fully (SOC <30%) but in the daytime there was plenty of sun but no feed-in. PV production showed approx 30W (sum of the idle consumptions). When I deactivated the AC ignore, the MPPT shoots to 180W.

So my best guess, there is room for improvement on the parameters of the AC input ignore namely, "connect on PV solar excess". I assume that if DC-Coupled PV – feed in excess can be detected, it can trigger the flow based decisions.

But as mentioned in the intro, maybe i'm completely wrong, and otherwise free to suggest a work around that manages to respond to my brainteaser.

Have a nice day, Philippe

Victron and the community, thanks for the good job.

ESS
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4 Answers
philippe avatar image
philippe answered ·

Hi @Guy Stewart (Victron Community Manager) I'm surprised that the ESS, once the SOC drops below the 30%, it does not charge it up to 100%. I got just a spike AC input from 28% to 30% and then stopped. So curious what I missed in the ESS.

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nickdb avatar image nickdb ♦♦ commented ·

You need to properly read the ESS docs, you don't seem to understand how it works.

ESS will discharge from batteries until you hit your minimum SOC (30% in your setup). At that point it will go to grid to service loads only. It will not charge from grid but will wait for PV and will then dedicate PV to charging until it gets to 3 to 5% (33-35% in your config) above minimum SOC. Then it will resort to using PV for loads and surplus PV for charging.

If you use battery life, the system will artificially increase your minimum SOC (the active SOC) to cater for lack of PV when it can't fully charge the batteries.

ESS will only use grid to charge if you either change modes to "keep batteries charged" or if, due to grid failure, the SOC drops well beneath the minimum set, in the latter case it will charge to near the minimum SOC, then stop and wait for PV.

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Alexandra avatar image
Alexandra answered ·

@philippe

AC ignore means the Victron does not connect to grid. This is meant for self consumption.

You can have ess on set the grid point to zero, have the feed in excess option switched on and then the feedback will happen automatically when it is able or above your own needs. So there is already something in place that suits your needs.

Ess also allows you to set how far to drain the batteries before feeding loads from the grid directly.

How is the unit supposed to send excess power to the grid when you told it to ignore the grid? In other words to not connect to the grid.

The manual for ESS states you cannot use ess in an ac ignore system.


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philippe avatar image philippe commented ·
@Alexandra for the same reason it connects on conditions as load, soc, low voltage, ....
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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @philippe,

I think there might be some misunderstanding - I made a video that explains how the ESS system works - please watch it, and hopefully it answers your questions on the ESS behaviour and clears up any misunderstanding.

https://vimeo.com/484986737

If it’s still not clear after watching that video, please post back :)


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philippe avatar image
philippe answered ·

@Guy Stewart (Victron Community Manager)

Went thru your video, and I was fine on the understanding, but in real live, apparently, I do something wrong.

ESS SOC put on 30%

As I see now, it pulls 33W from the grid, consume 13W on AC out without any consumer.....

screenshot-2022-03-31-at-142149.png


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