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gyrovague avatar image
gyrovague asked

How quickly should ESS switch to battery+inverter when grid fails?

I have Victron MultiPlus II 5kVA, 4x 3.5kWh pylontech batteries, 12x 395W 3s4p PV panels, 150/100 Victron MPPT, Venux GX, ET112 grid meter, all in a ESS configuration. When the grid fails (South African loadshedding, currently happens about twice a day), about 30% of the time I can see lights flicker and PC and TV and sound system etc. will reboot. The salesperson originally told me the system can switch within 20ms and will perfectly act like a UPS. The strange thing is that this happens even when in strong sunlight (basically all power supplied by sun, except for the small "grid setpoint" amount) or when already primarily using battery storage (early evening, after sunset), so in both cases everything should already be powered by the inverter, doesn't make sense to me that there would be a long enough dip in power when the grid (supplying merely a small "grid setpoint" amount of 150W) fails. At least two of the times these reboots/dips happened, there was no significant power draw, no stoves/ovens/geysers using the non-essential circuit, less than 1kW average drawn for the essential circuit,


[I have a perhaps tangentially related issue, where sometimes the system feeds back to much power into grid (while grid is working), causing prepaid grid meter to reset and cut-off the mains supply for a few seconds. There are various posts about this topic on these forums, and one of the hypotheses is that this is related to some kind of slowness between victron and the ET112 grid meter, so just mentioning that here in case that same alleged slowness could be causing this slow response to grid failure too]


Needless to say, this is extremely annoying, as the main reason I got this system was to act as backup against downtime from loadshedding. Any ideas?

ESS
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8 Answers
Paul B avatar image
Paul B answered ·

Make sure that the UPS function is ticked using ve config


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gyrovague avatar image gyrovague commented ·

I'll pass this along to my solar installer, it's quite clear that this software is not something that I as an end-customer should be using. I installed it briefly, and saw all the warnings about how it should only be used by qualified and trained people and that it can damage your system beyond repair etc., and promptly uninstalled it. :)

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ewalderasmus avatar image ewalderasmus gyrovague commented ·

Hi @gyrovague


You will be able to verify this by downloading the config through VRM and viewing it offline. That way you can double-check your solar installer.


Go to VRM-> Device List -> Remote VEConfigure -> then click download.


If you have VE configure 3 installed you can just open the file and check what has been done.


regards

Ewald



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gyrovague avatar image gyrovague ewalderasmus commented ·

hmm, when I go to vrm.victronenergy.com website and view my installation, I go to Device List (on the left), but it just shows a list of things like gateway, Ve.bus system, battery monitor,solar charger etc.,but I don't see "remote VEconfigure" anywhere on that screen or inside any of those expanded devices.

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ewalderasmus avatar image ewalderasmus gyrovague commented ·

It might be that you do not have full control of your system.

Speak to your installer about this. Seeing as its your system you should have access to it.


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nickdb avatar image nickdb ♦♦ gyrovague commented ·

in the GX. Go to settings -> VRM and make sure two-way comms is enabled.


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gyrovague avatar image gyrovague nickdb ♦♦ commented ·

This two-way comms did the trick, thanks @nickdb!

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gyrovague avatar image gyrovague ewalderasmus commented ·

@EwaldErasmus Now that I've downloaded that config from VRM and loaded into VE configure, I don't see that section with the UPS checbox at all, mine looks like this:

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nickdb avatar image nickdb ♦♦ gyrovague commented ·

Had some TVs restart tonight when the grid was lost . It was a noticeably larger flick of the lights when it changed to inverting. Guess the cutover isn’t always as seamless as it should be.

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gyrovague avatar image gyrovague nickdb ♦♦ commented ·

Ugh... :( My PC has rebooted a few times while I've been working, the main reason I got this whole expensive setup was to protect against loadshedding, and now it's not doing that.

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nickdb avatar image nickdb ♦♦ gyrovague commented ·

It should not be doing that, not to that extent, so often.

Part of the problem may also be due to how the grid is being powered off. It was rare for me to notice the grid being lost, particularly on devices that have been fine previously, but it also happened to a friend down the road at the same time. Would suggest you get your installer and distributor involved to look at why this is happening so regularly.

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ewalderasmus avatar image ewalderasmus nickdb ♦♦ commented ·

Hi @gyrovague


I have had similar issues with some of my sensitive equipment. I have a 8kVA Quattro and although most of the equipment doesn't notice the load-shedding some of my more expensive test equipment does... I solved the problem by placing an inline UPS on those loads. I already had the UPS's so it was at no expense to me... I assume that because the equipment is rather far away (in wire length) from the inverter, there is a larger delay in voltage change over, large enough for the system to notice it and shut down...

I have been trying to read on using AC caps for low voltage ride through... but haven't had a lot of time to read on that. I cant see why it will work but I have had a few colleagues mention it, so I will have to get my oscilloscope out and test it one day.

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solarhack avatar image solarhack gyrovague commented ·

The way I understand it is the UPS mode only works if you are not using a grid code and an assistant requires a grid code. It is for people who only have an inverter and battery and are connected to the grid with the battery as a back up. Once you enable an assistant (ESS in this case) the UPS mode is disabled.


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gyrovague avatar image gyrovague solarhack commented ·

So you're saying in ESS mode it cannot do the fast seamless switchover? That sounds worrying ..

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solarhack avatar image solarhack gyrovague commented ·

When you are on Solar and or battery you shouldn't see any impact when the grid fails as your critical loads are already using the inverter. You should only see this when you are not on solar and the battery has reached the cut off.

I have observed the reaction of the system switching appears to be related to how the council cuts power (or a brown out), the size of your battery and the your setup (Wire lengths, age, etc.)

The Victron can switch in 20ms but this is constrained by the grid specifications and items listed above



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nickdb avatar image nickdb ♦♦ solarhack commented ·

Many grid-tied installs (especially when backup power is a concern) have more appliances attached to them than the inverter can power on its own, with passthrough from grid covering the slack. This is a much cheaper way by avoiding massive rewiring.

Solar/batteries may only power part of the load or an ESS inverter limit is set, so it is no guarantee of a seamless failover.

The issue seems to be more about brownout as suggested before.

If you can drop the supply breaker and nothing has an issue, the problem is on the grid side.

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nickdb avatar image nickdb ♦♦ gyrovague commented ·

The system isn't actually that complicated, you just need to have some electrical knowledge and understand the various mechanisms.

There is a lot of good info but it is scattered across different manuals and tutorials, It would be nice if it could all be compiled into something that is more of a digital wizard or tailored how-to for typical scenarios.

The UPS function works well, I notice the slightest flick on LED lights when eskom cuts power. Enable the grid-lost alarm on the GX, that way it will notify you when the power is cut.

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dylan-hyslop avatar image dylan-hyslop commented ·

Why would the South African grid code not be setup for the load shedding parameters by default? It's literally the reason we all get these systems in the first place?

Can I still run ESS with grid code other in SA?

What is the password to change it?



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karel avatar image
karel answered ·

I have a 48/3000/35 MultiplusII with 1 pylontech and venus gx + 4000 W PV etc. and found similar problem. During the day when load shedding happens all appliances (TV DSTV etc) are fine i.e no rebooting at all. During night time, no sun or pv input, when load shedding happens, my TV and AV system reboots but my DSTV decoder does not reboot. Was also wondering why the resets happen at some stage. When simulating load shedding by manually switching off my main breaker I also have no resets at all.

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Alexandra avatar image Alexandra ♦ commented ·

@Karel

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom#minimum_battery_sizing_recommendations

I have seen flicker on changeover for several reasons

1 - high grid line impedance

2- battery is smaller than recommended for the system

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom#minimum_battery_sizing_recommendations

3 - undersized cables feeding the AC in in the installation

4 - brownouts make all of this worse increasing the amperage drawn as the grid is failing.

5 - incorrect earthing.

6 - grid code settings and LOM can also be a related issue.

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bonie-wanda avatar image
bonie-wanda answered ·

Hi

I also experience the same problem.The multiples ii 48v/3000va is so slow such that the modem and router loose network connection over and above the lights flickering.

Bonie

Johannesburg

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi

I think the problem here is when the blackout is more like a brownout: AC voltage dropping slowly, until it finally reaches the disconnect limit.

The problem is usually that the inverter follows the input AC voltage, and when finally disconnecting it has trouble getting the loads back up to voltage.

As some grid-codes don't allow setting the disconnect limit, I'd try to run the system without a grid code (so no ESS!) and set the AC disconnect at a higher level (like 210V)

if this works: try using grid code 'other' and use an external anti-islanding device. (with grid code 'other' you can set the disconnect voltages).




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ewalderasmus avatar image ewalderasmus commented ·

Hi @Daniël Boekel (Victron Energy Staff), Thank you this is very helpful. your explanation makes a lot more sense, so thank you, and sorry for bugging you.


I think South Africa is a difficult situation, as we have small supply interruptions as well (lasting less than 1s probably only much less) so setting that limit as high as 210 could impact other situations. I have had a few instances where the inverter kicked in but for no noticeable reason, and I can only assume it was an instantaneous voltage dip.

I am running my system without ESS, and with no grid code, but AC disconnect is set at 180V, which as you said could be the issue (slow voltage drop), coming to think about it it makes a lot of sense now, as when I simulate load shedding (dropping mains at the incoming CB) I have no issues with my loads, nothing sees the changeover, but during loadshedding when the utility turns off the supply to the mini-sub, they go off...

I would almost like to say there is an opportunity to interface the load-shedding schedule into the system and allow it to be more sensitive during the hour when load shedding is set to start, also giving users who run ESS systems the option to charge up the batteries before loadshedding...


Thank you again for your response.


regards Ewald

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PeterM avatar image
PeterM answered ·

My MP switches perfectly , no rebooting during loadshedding.

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dylan-hyslop avatar image
dylan-hyslop answered ·

I am having the same issue, my computer reboots every time load shedding happens.

I am running a full ess system with multiplus II 3kva.

I cant see the UPS function in the VE Configure app. I have set the grid code to South Africa for the feedback function to work correctly.

I understand the brownout problem, which makes electrical sense, but how do I solve it? The main reason for me getting this system, and paying extra for Victron was so that I can work from home with Zero interruptions?

Do I really need to buy another inline up just for my computer?

Can I change the grid code to OTHER? and still have full function of ESS with push back?

I also noticed that our load-shedding has been at 5pm (evening) and my battery is often at 90% (my cut off voltage for ess) so the Inverter is primarily running from mains at the time of the ac power dropping.

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kosmos avatar image
kosmos answered ·

Any definitive resolution to this issue guys? Not had this issue on any other Victron Q or MP I have installed, but now I have it with a 8kVA MPII at a site. ESS assistant not added, UPS ticked, I've set the low AC to 200 V. Just an Inverter, Colour GX and some Pylontech UP5000's

Elsewhere the Victron Inverters always kicked in, hardly anyone notices the switch over, but now its an issue here. Lights momentarily dip, routers etc reset.

But there is some seriously dodgy electrics on the db that this is connected to (in true South Africa style) I am thinking maybe its that. I replaced a 5kVA MP / 24 volt with this 8000 MP II so did not do the db rewiring, took one look in the db and its like .. EEK! Essential circuits not separated, circuit breakers wired to the Inverter feed all over the place, and the Neutrals commoned. ELP tripping most of the time when Inverter switches back to mains. I plan to redo the whole thing but pressure was on me to get something working due to on-going Load Shedding in ZA.

Also getting a quiescent load of around 3kW that no one can tell me anything about....

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dieter-lubbe avatar image dieter-lubbe commented ·
Did you resolve this issue?
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Constant avatar image Constant commented ·
I'd also like to know if there was a resolution.

I also have slow switchover which causes computers to die.
Similar setup with Quattro, Colour GX & Pylontech batteries
Using

Using ESS with "Other" grid code and UPS function with Low AC Disconnect at 200V

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dkronie avatar image
dkronie answered ·

I also get these disconnects but randomly and mostly at night , reading through the thread I also think it is "... more like a brownout: AC voltage dropping slowly, until it finally reaches the disconnect limit. "

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