Grid-Parallel ESS (Split Phase) won't work autonomously - No Charging or Grid Injection

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Ricardo Chavarria asked Jun 1, '24

Grid-Parallel ESS (Split Phase) won't work autonomously - No Charging or Grid Injection

Hi Everyone,

I've been running my Grid-Parallel ESS (Split-Phase) for about 6 months now and things were going well, but because I did not have a Grid Meter, it wouldn't count consumption or grid-feed-in properly.

Two weeks ago I installed an EM530 and it's working well showing consumption, but I've ran into a problem where the system is not stable unless I control it manually. Here are the issues:

When PV production is higher than consumption, it won't inject into the grid unless I set the mode to "external control" or Pass-through.
When PV production is higher than consumption, it will overcharge my battery and go into High DC-Voltage Alarm, unless I set the mode to "external control" or Pass-through.
I've had to create a bunch of manual settings with Node-RED so the system half-works as I want.

Any help would be greatly appreciated...I'm at a loss manually controlling my system daily...

Here's how my system is configured:

This is how it shows when I'm manually controlling it.This mode won't let the system feed into the Grid, and it'll over-charge the battery if full.I don't know how to set it so it won't have Feed-in limiting...I can feed as much as I want into our GridCustom controls so I can avoid High-DC Voltage Alarm by forcing system into Passthrough mode.Forcing "Disable Feed-In", as it's the only way to get the system to actually feed into the grid.

ESS Node-RED BYD split phase grid parallel

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Ricardo Chavarria commented · Jun 02 at 12:58 AM

An update on my setup, my Grid Meter had the Phases swapped in comparison with the Multiplus. I've swapped it so L1 correspond's to the MP's L1.

Other than getting proper measurements now, I don't know if this will affect anything, but I'll report back tomorrow.

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Answer 1 · 2024-06-01T21:48:12Z

rickc answered · Jun 01 at 09:48 PM

I don't have any AC-coupled PV, so I'm probably not the best person to help you.

However, shouldn't AC Coupled Feed-In Excess be enabled?

Also, running in Keep Batteries Charged mode is pretty limiting, considering you have a nice big LiFePO4 battery. Perhaps letting the battery be a buffer for the PV during the day is the way to go. However, I don't know what your needs and intentions are, so I apologize if these are naive comments.

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Ricardo Chavarria commented · Jun 01 at 10:40 PM

Thanks for your comments. As far as I know, AC-Coupled has to be setup with PV on the Output side of the multi, and requires following the 1.0 Rule - neither applies to me.

I don't mind running one of the battery optimization modes, but it has just resulted in wonky behavior, including discharging during the day when I hace plenty of excess PV Power.

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Answer 2 · 2024-06-02T02:28:04Z

rwall1016 answered · Jun 02 at 02:28 AM

Funny, I just came here to seek an issue I'm having, but might be the same you are.

The offending setting is "Self-consumption from battery" set to "Only critical loads".

For me, this ignores all other ESS related functions and is equivalent to "Keep batteries charged" with no export. Once the batteries are full, excess solar ends up being wasted as it won't feed the non-critical AC loads.

What I would EXPECT this setting to do, is still honor the Minimum SOC and peak shaving options, but only give up battery power to critical loads and peak shaving. Allowing excess solar to still go to non-critical AC loads and obviously, I wouldn't expect it to recharge the batteries using the grid.

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Ricardo Chavarria commented · Jun 02 at 04:19 PM

Unfortunately that made no difference. I can still see the same wonky behavior where the PV Inverter gets throttled down and won't produce/inject over consumption. It even goes down to 0 PV Production at some point...

Self-consumption from battery set to "All system loads"Right after that I set the system to "Keep Batteries Charged" mode and it shifted to "Disable Grid Feed-In" to No, which made the system not export anymore...Ultimately I switched back to having my manual control (Passthrough mode), and it started feeding into the grid back again...

So...I'm at a loss...I don't think I've gotten to the bottom of this. Yes the phase difference problem could have caused some problems, but I don't think it was the main culprit, there's still something configured improperly that doesn't let the system export to the Grid when it should...

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Answer 3 · 2024-06-03T04:45:39Z

Kaj Lehtinen answered · Jun 03 at 04:45 AM

Try enabling feed in access to the grid (Ac-Coupled PV - feed in excess) - that should make the system start to feed in to the grid when batteries are full.

What minimum SOC level have you set?

Also, I would not run in 'Keep batteries charged' mode. ESS knows that it should charge the batteries first and will try to do that if it still can keep the grid setpoint at what you set it to (50W in the pictures).

Also, my experience, although not with BYD batteries but with Pylontech is that voltage high alarm when SOC > 97% can be cell inbalancing that manifest itself. The solution then is to keep the batteries at SOC 100% for as long as it takes for the balancing feature in the batteries to do its job.

/Kaj

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Ricardo Chavarria commented · Jun 04 at 04:26 PM

Thanks for your suggestions. If I go by the book, I should NOT enable AC-Coupling, as my PV Inverter is on the INPUT side of the Multi:

In an AC-coupled system, a grid-tied PV inverter is connected to the output of a Multi, Inverter or Quattro. PV power is first used to power the loads, then to charge the battery, and any excess PV power can be fed back to the grid.

https://www.victronenergy.com/live/ac_coupling:start#what_is_ac-coupling

As far as your other questions, I've set minimum SOC as 85% right now.

I've gotten the system to be stable by setting my Grid-Setpoint to -7600W, my PV Inverter's maximum. This has gotten everything back to normal, including feeding into the grid, maintaining batteries charged while not overcharging them.

I'm going to keep the batteries charged at 100% SOC as long as possible and check the cells to see if everything is ok.

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Grid-Parallel ESS (Split Phase) won't work autonomously - No Charging or Grid Injection

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