Can i use a multiplus 2 without notifying my grid supplier?

Question

question

mfred68 asked Mar 3, '24

Can i use a multiplus 2 without notifying my grid supplier?

I have recently acquired 20kwh of batteries, I already have 4kw solar panels. I plan to get a multiplus2 to charge the batteries on an economy 7 tariff (I'm in the UK) for cheap rate charging, then once normal rate kicks in, I want the inverter to totally disconnect itself from the grid, so there is no feed in, and I'm totally off grid, until midnight when economy 7 starts, and yhe inverters contactor to the grid engages again to charge the batteries. To me , I regard this simply as an appliance like a fridge , or an immersion heater, which don't need grid permissions (I.e. red tape and bureaucracy with extra expence) I am an a tight budget, and dispise paying people just for a piece of paper.

So can this charging method be used and go totally off grid from the inverters output side?

offgrid

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matt1309 commented · Mar 03 at 11:26 PM

Hi @mfred68

There is an assistant for this I think called ac ignore but I might be wrong there.

I am of the same opinion as you. And hate the whole mcs thing in the UK.

However mcs isn't required and only needed for selling power.

However I believe you do still have to inform dno even under your planned setup.

That said I've seen many examples on here and other forums where competent people have complete these forms and installation themselves without question from dno or cost.

Its not guarantied, they can charge Usualy if the line needs upgrade or if they need/want to inspect.

Some dnos will want to come inspect, typically I find this only happens with unusual/large systems but that's not a hard rule. They can come out regardless of size.

Fair few examples you can find on here with others complying the forms themselves with success.

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bladerunnervf commented · Mar 03 at 11:52 PM

Are your 4kWp pv already installed and exporting with DNO agreement?

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matt1309 bladerunnervf commented · Mar 04 at 10:24 AM

Hi @bladerunnervf

I believe the requirement is different given it's a battery. However this will definitely improve the chances of them just reviewing the forms and saying it's ok. As from their point of view it's no extra work...

(I actually used Daza's line diagram who's commented below for his system and just photoshopped it to align with my setup for my DNO submission).

For the sake of one form and being able to have a "normal" install without install quirks I'd give it a go.

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Answer 1 · 2024-03-03T23:52:25Z

daza answered · Mar 03 at 11:52 PM

@mfred68 short answer is no if you are in the UK you have to notify your DNO of a generator type connection, that also covers battery storage.

There is a huge demand on the grid they have to make sure that it’s not going to overload there transformers especially if you then add EV Heatpump into the mix and to check the design of the system. The day and age we live in where you can get inverters and the like from everywhere they make sure it’s compatible.

Cant speak for all DNO’s regarding pricing of G99 but I done it on my own with the help from forum members and (UK Power Networks) me nothing for this.

If there ever is a fault that requires the grid at your address it might be hard convo if they pick it up. The only off grid is no grid connection you are charging from the grid so you are connected to the grid so it’s not going to be off grid.

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Answer 2 · 2024-03-04T06:21:50Z

Michelle Konzack answered · Mar 04 at 06:21 AM

You can run the MultiPlus-II in "Generator mode" and simply put a contactor with a timer on it.

Then you will NEVER feed-In and your Batteries are charged only in the specific time.

This will AFAIK not require an authorisation.

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Answer 3 · 2024-03-04T08:05:30Z

ejrossouw answered · Mar 04 at 08:05 AM

@mfred68 If you set the grid code to 'not allowed to feed DC in', then yes. Much the same as with mobile and off-grid installations. ESS cannot be used and scheduled charging won't be available. In simple terms, the inverter won't run when there is an active grid connection and only run when the grid is disconnected. Be mindful that this way you can overload the system as it won't use AC for shortfalls as with ESS, but can be configured with AC ignore to completely switch over to AC (passthru) when certain conditions occur. Could prove more problematic with some appliances e.g. ovens that switch in and out. As for demand management, it is primarily for the grid synchronised feed-in aspect given properties have a cutout rating of typically 100A in newer properties which the DNO should already be able to supply regardless of the type of load e.g. your 32A plasma cutters, hottubs etc. that the are blissfully unaware of :) First image shows AC ignore and second ESS which requires DNO applications/notifications.

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Answer 4 · 2024-03-04T08:43:56Z

delf67 answered · Mar 04 at 08:43 AM

AFAIK There is no requirement to tell your DNO about ANY appliances that consume electricity being installed.

They only require notification if you are feeding back into the grid.

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sharpener commented · Mar 04 at 09:03 AM

Not correct, you need to get DNO permission in advance to connect a heat pump or an electric vehicle charging point.

https://connections.nationalgrid.co.uk/get-connected/

Also I am not convinced you do not need it for any connected Multiplus installation, since by changing the operating mode it is capable of generating and feeding into the grid.

That is the test the DNO applies, not whether it is actually used that way.

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ejrossouw sharpener commented · Mar 04 at 12:17 PM

Would be problematic for DNO's in that large mobile installations hook up to grid/shore supplies all the time. Even the smaller 500VA Victron models can be configured as an ESS, but will never pass certification given the lack of dual redundant relays etc. and as such DNO's will also never be interested. The problem for me is more the current implementation of the grid setting in that it should be by default locked to "no DC feedin allowed" and only be changed by an "authorised party" using the manufacturer's code when in receipt of a DNO notification receipt or approval. Strangely a code is required to change the grid once it is set, so maybe an improvement opportunity.

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sharpener ejrossouw commented · Mar 04 at 12:38 PM

Up to and including the Multi 3k the potential feed-in is below the 3.68kW "connect and notify" limit so DNO's aren't really worried. Perhaps they ought to be, as a shock from a 500W inverter is still a 230V shock.

With the 5k and larger units they believe there is a real possibility of feeding in enough current to take the supply voltage above the upper limit, or at any rate that's why they told me they wanted the generation capability restricted.

Have never been able to fully understand this reasoning, surely the net effect of starting up 7kW of generation is the same as switching off an EVCS that was drawing 7kW, which they are quite happy for me to do.

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ejrossouw sharpener commented · Mar 04 at 04:11 PM

If you use AC ignore, there is no risk of feeding in as the dual redundant ACIN relays (2 per leg) are open and there is no active connection to the grid on ACIN as per the first image above. When the ACIN relays are closed the inverter is OFF and the system is in passthru, so no power is generated.

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sharpener ejrossouw commented · Mar 04 at 08:15 PM

I know that. You know that. The DNO may know that, however they also know that without any physical changes to the wiring someone can re-program it to generate and export up to the max capability of the inverter.

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ejrossouw sharpener commented · Mar 04 at 09:25 PM

From a risk perspective I am hopeful DNO's risk models would incorporate some decent safety margin, especially given DNO's in principle should already allow for EACH household to be able to export 3.68kW they cannot refuse from my understanding. With still "relatively" little solar uptake it should leave decent headroom apart from in older infrastructure areas. Also, these "off-grid" minded individuals will most unlikely ever give their energy away, which means no risk of such exporting if you ask me? ;)

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sharpener ejrossouw commented · Mar 05 at 09:43 AM

Even if <3.68kW they also need to know where the generators are on the network and that they have appropriate anti-islanding to help prevent their operatives being electrocuted when working on supposedly 'dead' cables. Or that is the theory. As you point out, the smaller Victron inverters do not have this feature implemented fully but can still export.

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Answer 5 · 2024-03-04T13:09:33Z

daza answered · Mar 04 at 01:09 PM

As @sharpener i believe they should be notified and I would say prior to connection as the potential power is over 3.6kW meaning DNO notified prior to connection to the grid rather than the notification after connection that any potential power connection of 3.6kW or below allows as for shore/grid I don’t know if they have mechanisms in place as fail safes or allowances I’m only commenting on the domestic home side of it, but it doesn’t matter what I believe as it needs to be official from the horses mouth so to speak.

I have emailed my supplier UK Power Networks for a formal response around this area (No Posts have been linked just me asking questions for a formal response) yes I know there are many DNO’s in different regions but I imagine this will be all DNO’s that would adhere to this.

This is why I have asked for a formal response and imagine it would have to go through a few channels before an official response so I imagine really slow. Saying that they have been really fast every other time I had to contact them.

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ejrossouw commented · Mar 04 at 03:10 PM

The OP should personally contact his DNO for an answer as I can give examples of members in this forum with the same DNO where one is requested to limit output of a system to less than 3.68kW while another with the same DNO obtains approval for a parallel 5kVA installation and 4.4kW export.

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Answer 6 · 2024-03-04T15:33:02Z

daza answered · Mar 04 at 03:33 PM

@ejrossouw yes OP should, but as OP requested help from a public forum which all have access to and may take comments as a definitive answer IMHO it can only definitely come from a definitive source.

“I can give examples of members in this forum with the same DNO where one is requested to limit output of a system to less than 3.68kW while another with the same DNO obtains approval for a parallel 5kVA installation and 4.4kW export”

On examples you outline the DNO was contacted to one impose a limit and second to approve without a limit. In both examples the DNO would have been notified in order that the recipients receive the above approval conditions.

Either way this lands I’ll put the full email minus my details and this will hopefully be definitive as I’ve asked for definitive answers not just what they have on there website.

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ejrossouw commented · Mar 04 at 10:14 PM

@Daza The right and best advice is for the OP to seek the answer directly from his DNO, hopefully armed with knowledge and a better understanding of how the systems differ, gained from this forum. This information the OP can use to engage in a meaningful discussion with his DNO without an application, much like you are ;) The forum will not always have the answers as in this case and can definitely not speak on the part of his DNO. My other point was that just as outcomes can wildly differ with the same DNO based on various factors, my experience with customers all over the UK, is that it varies even more between DNO's and even the individual engineers. And no, you do not have to notify or apply to obtain the appropriate guidance on whether to submit an application or not! I look forward to the OP's feedback however.

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daza ejrossouw commented · Mar 05 at 07:51 AM

@ejrossouw the two points are guidance points from the DNO about the devices connected. The topic is not guidance so let’s keep it to the device as OP has posted instead muddying already muddy waters. Although I can see the logic in the answers people provide ultimately it's not what we deem or think.

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Answer 7 · 2024-03-05T08:05:51Z

John Dent answered · Mar 05 at 08:05 AM

I agree that you should request permission of the DNO.

there may be ways to disconnect entirely, working around the need. But easier (IMHO) just to request, and reserve that evasive action for if they (unlikely) refuse.

FWIW, I just requested to connect a MP-II GX/5k, and saw no problems nor even queries.

The 5k version is request and approve, but it is possible that the 3k version is notify-only due to being below the power below the threshold requiring it to be request.

Call up your DNO and ask for their guidance on what form to fill and so on.

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Answer 8 · 2024-03-07T12:19:22Z

daza answered · Mar 07 at 12:19 PM

[moderator note: edited slightly to differentiate user statement from quoted DNO statement]

As promised a response from a DNO ( UK Power Networks ) in short yes you have to tell them, they also go into detail of the occasions when you don’t:

"Good morning,

Thanks for your email.

Any device being installed, even if the export is set to 0kW, must be registered as compliant on the ENA database so that they automatically shut off any potential export to the grid when there is a power outage (manual shut off will not be compliant).

If you are installing a battery to the DC side of an existing system and inverter, then you do not need to notify us as there is no change to the export that is already approved by the DNO. If the existing system does not already have an approval, then you will need to make the relevant application depending on the total export.

If there is no existing system / inverter and you are only installing a battery, then you will still need to notify us even if you are setting the battery to 0kW Export as the inverter for the battery will have the capability of exporting.

If the inverter for the battery does not exceed 3.68kW (the max. export capabilities will never exceed 3.68kW even if you set it to 0kW Export) then you will need to submit a G-98 Notification along with a SLD Schematic which can be done after installation. This will need to state the Export limit; if this is set to 0kW then you will need to accompany the application with a G-100 Declaration confirming the inverter will never export to the grid.

If the inverter for the battery exceeds 3.68kW, for example a 4 or 5kW inverter etc., then you will need to submit a G-99 application and SLD Schematic prior to the installation. As above this will need to be accompanied by a G-100 declaration if the Export will be limited to 0kW.

All forms can be found on the ENA website.

Regarding what we class as import when the battery is charging and if your supply is sufficient for the additional load, this will have to be investigated by an electrician who will calculate your usage including the device to be installed; we only assess the export onto the grid (any change in import will have to be discussed with an electrician and if your supply or main cut out fuse requires upgrading then you will need to come to us before hand)."

Kind Regards

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ejrossouw commented · Mar 15 at 11:05 AM

[moderator note: removed unnecessary personalization of comment]
Given the existing G98/G99 commissioning tests cannot be applied to an AC Ignore system, I wonder how the DNO proposes to answer that?

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daza ejrossouw commented · Mar 15 at 02:20 PM

@ejrossouw "[moderator note: edited] Given the existing G98/G99 commissioning tests cannot be applied to an AC Ignore system, I wonder how the DNO proposes to answer that?"

[moderator note: edited]

(1) It answers AC ignore which is a setting to enable 0kW export, it doesn't matter as the Device itself is still Capable Of Exporting that is in built,

"even if you are setting the battery to 0kW Export as the inverter for the battery will have the capability of exporting"

(2) I don't make the rules that is a national infrastructure thing that DNO's enforce, i just follow them. (3) Even if i was wrong about what i said about notifying the DNO i would still post what the DNO said as its learning for all and everyday is a school day. (4) Forum is a learning tool for all and the source of open information, if i was researching this Topic i would want the right answer and what better way than from the horse's mouth so to speak aka DNO!

The Original question OP has posted has been answered in full and i see no reason to comment further the answer is there for all.

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ejrossouw daza commented · Mar 15 at 05:12 PM

"even if you are setting the battery to 0kW Export as the inverter for the battery will have the capability of exporting"

I disagree as there is NO active grid connection (relays are open) with AC ignore which is NOT the same as with an ESS grid setpoint of 0 and gridcodes configured and has an active synchronised connection with relays closed. Furthermore, it opens a whole can of worms given ALL those mobile and marine applications with Victron or similar systems and shore hookups with automatic transfer switches should then get ready to submit their G98/G99 notifications or applications?

"The Original question OP has posted has been answered in full and i see no reason to comment further the answer is there for all."

Definitely not as his DNO is the only authority who can ultimately answer his question.

You are however right and we can leave it at that as from my experience with various DNOs and having actually seen outcomes to the contrarary based on someone taking the time to dicusss and fully understand the technical configuration (it involves actively engaging with the DNO and asking the right ask the right questions ;)

On the lighter side of things. I'd love to the how a system can be at risk of exporting when it is charging from AC (technically not possible) or how to test the disconnect and connection times of a system that does not actually have an active connection with the grid ;)

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matt1309 ejrossouw commented · Mar 15 at 05:54 PM

Playing devils advocate here.

But i feel like the assumption here is the system is configured correctly and not faulty. If i was the DNO I would want to confirm/test that somehow.

Like you say How can a system be at risk of exporting when it's charging.

It cant but what if the system is misconfigured/faulty and it unexpectedly exports rather than imports when grid connection is live. either through misconfigured assistants or just a major fault with the inverter.

Commissioning tests (and not just those described by DNO) would spot this. As you mention there would be no disconnection speed result under AC ignore mode. That to me is itself a test proving that the inverter is not configured as ESS.

Tbh not sure how mobile installations get around this. As a random guess i would say you sign something before getting access to a hookup to confirm you wont/cant export power.

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delf67 matt1309 commented · Mar 15 at 06:24 PM

I've never been asked to sign anything when plugging into hookup at a caravan site, but even if I had, as you said in your post... "what if the system is misconfigured/faulty and it unexpectedly exports rather than imports"?

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matt1309 delf67 commented · Mar 15 at 07:01 PM

Surprised at that. Would've thought for site safety they'd want something.

Surprised there's not even a disclosure that says something to the effect of they're not liable if you harm yourself using it incorrectly. Would've thought at the very least they'd have paperwork for that. I guessed it would've been something like that and confirming not able to back feed would be in there.

I've never installed a hookup but can't spot any anti back feeding devices in them anyway.

Gven the fuss made over testing ess installs youd have thought that they'd want to confirm that they aren't installed on mobile installs.

Like commissioning tests on ess system such as disconnection times youd think in theory they'd want to prove that there isn't a connection in ac ignore systems

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ejrossouw delf67 commented · Mar 16 at 07:50 AM

@delf67 The default out of box configuration of a system will be charge/passthru when shore is connected. When you upgrade firmware it always defaults to this. No risk of feeding in. You can use either AC ignore VS or ESS but it won't allow both. However, ESS is more complex and daza's lack of understanding misconfiguration of his system is actually a good example. However Victron clearly states ESS should not be used in off-grid (also read mobile) types of installations. So, there are safeguards and as I proposed, there should also be some lock there only allowing professional installer to enable grid parallel feedin. I know the latest version of VictronConnect has a lock feature, but have to see exactly to what level.

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matt1309 ejrossouw commented · Mar 16 at 08:35 PM

I'd probably argue given the device is capable of such behaviour the risk isn't 0.

If I equate it to something else.

If Im working on a circuit. I turn off the disconnect switch for that circuit which assuming everything is working then the power would be disconnected and safe to work on. However I'd personally still check (test) to confirm the disconnect was working as it should.

Incase the switch is faulty/not wired (configured) correctly. That's how I view it. Multiplus wouldn't be able to export if configured correctly. However given the device is capable of exporting if not configured correctly, I'd still want to test it.

I think Daza and Dno are not saying Ess with grid setpoint equal to 0. They are talking about AC ignore. They're saying given the multiplus could be configured in a way In which the inverter could export you need to test that it isn't configured in this way.

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ejrossouw matt1309 commented · Mar 16 at 10:58 PM

Installs should be carried out by competent and suitably qualified personnel trained on the product which should mitigate risk. Secondly, fully type tested products are equipped with dual redundant relays to avoid such HW risk. A good topic, but I do not believe either daza nor the DNO answered the right question and will close the topic as such. The OPs DNO is the only authority to access the risk to them for what is not NOT an ESS grid parallel system and make the actual decision on how to test it.

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matt1309 ejrossouw commented · Mar 17 at 12:11 AM

i agree no one can really answer this other than OP's DNO. And from my experience it'll likely depend on who at said DNO they speak to as they are often inconsistent.

However I do feel it's inconsistent to argue that suitably qualified/competent installers is sufficient to not inform DNO for non ESS configured inverters. Yet insufficient for ESS configured device.

I see your argument that the inverter "shouldnt" be able to export when configured in the correct way with relays as a safety mechanism... but the "shouldnt" word is the bit that i would want tested if my life depended on it.

The DNO's I'm familiar with dont seem to differentiate in their requirements between ESS configured inverters and non-ESS configured inverters. I assume they group them under "inverters" to cover themselves against inverters mistakenly configured as ESS when they shouldn't be or faulty inverters (ie 2 failed relays) that exhibit behavior that they shouldnt be showing

But like you said pointless discussing given DNO can make up their own answer, and often feels like they do.

It sounds like answer to OP question is "no you need to at least ask DNO if you're allowed this setup even under a non ESS configuration, it's their network their rules"

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Al matt1309 commented · Mar 17 at 12:50 AM

No mooring I've ever been to or any camp site with a mains hook-up has ever contacted the DNO before allowing me or any other boat or caravan with an inverter, before allowing charging AFAIK, and certainly I've never signed any declaration of non feed in. Maybe this could come, but unlikely, as a competant person would not install an ESS on a plugged connection. I think people are getting a bit confused and tied up in ESS brain, thinking a system that can do ESS is an ESS, when it isn't.

Systems should still be installed by a competent person to the regulations, and like the OP in this thread, it won't be set up for grid feed in, it's not an ESS, it can't feed in, It's just a load like any other as far as the DNO are concerned, and not really any of their business... Until it is set as an ESS, and then the DNO need notifying, and the installer/owner is liable, but it isn't.

I wouldn't bother them for this, but I live on a boat and building regs don't apply, wiring regs are a bit different too, and I'm fully aware and regularly have to explain to people the reason and dangers for why boats etc with a plugged connection are not allowed to be an ESS, and should never be allowed to feed in to the grid: because the pins could be live long enough (backfedding) to electrocute for a split second when the plug is disconnected.

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matt1309 Al commented · Mar 17 at 01:15 AM

I always assumed when you paid for hook-up there would be some set of rules of using the hook-up. And part of that would include not exporting power.

If i was running the hookup and didnt have any rules I'd be worried that customers could end up back feeding into the hook-up and then get hookup host in trouble with DNO for exporting power without permission.

I suppose if there are no rules/agreements for using the hookup, what's the guaranty that the customer has had it installed by someone competent.

I thought for this reason they'd have some form of rule/contract in place to at least pass the blame over to user of hookup. But maybe not.

"I think people are getting a bit confused and tied up in ESS brain, thinking a system that can do ESS is an ESS, when it isn't"

I feel like that's the key point! The DNO dont mention ESS. All of their requirements say inverter rather than ESS device.

Multiplus is still an inverter if ESS is not configured, so I've always taken that as meaning DNO need to be informed if multiplus is connected to grid, regardless of ESS configured or not.

My guess for why they've done this was because there's a chance the inverter could be missconfigured/faulty and then could export power.

ie it's not like any other load as if this load is faulty/misconfigured it could export power. Whereas any other load isn't able to generate power even if misconfigured

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atebee commented · Mar 17 at 06:08 AM

Never heard of a UPS that is used for telecoms/IT equipment requiring any interaction with the DNO when installing. And none of them are listed as ENA type tested.

Seems like a very similar use case to a out of the box Multiplus without ESS enabled. In fact we use Multplus as UPS at some sites.

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matt1309 atebee commented · Mar 17 at 10:31 AM

That's a good point. And it is similar but for me the difference is a UPS cannot be configured to export power.

So you cannot missconfigure it, whereas multiplus could be.

I suppose if dno were only concerned with ess enabled systems why don't they say that rather than inverters as a whole

Why use the word generic word inverter at all if all they are only concerned about is inverters configured to export power.

It just feels flawed to say inverter configured with ac ignore we don't need to test it/assume it works as it should.

But when ess configured. It needs to be tested/not trusted to work as it should.

If ess configured correctly software stops it exporting power above a defined threshold. Yet dno need to be informed and tests complete even with the thresholds set. With the above logic you wouldn't need to inform them at all.

I suppose if I follow the logic above of "the multiplus is configured in a way in which it won't export so don't need to inform dno or test"

That would imply if I had 4kw ess system configured with grid setpoint of 5kw (so essentially a system providing power assist only). I wouldn't need to inform Dno? So does that mean some ess systems don't need to inform dno if configured in that specific way?......

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atebee matt1309 commented · Mar 17 at 12:33 PM

With the right knowledge a UPS could probably be reconfigured to grid feed, likewise with the right know how a Multiplus can too. Where is the line drawn?

There is also probably some fault condition on the internal relays of a UPS which could leave the inverter and grid connected. Again probably a line drawn through a British Standard to ensure the probability is very low.

There is probably a regs guru somewhere that can answer the OPs question with authority. Or the answer may be "it depends" then a string of various risk balances and mitigations which is what regs codify anyway!

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Answer 9 · 2024-03-15T21:49:50Z

tig-170 answered · Mar 15 at 09:49 PM

In short - yes, as soon as you've gone into ESS mode with the MP-II - I've just gome from total off grid to using ESS. The DNO (they came round last year to provide us a TNCS earthing system / fuse upgrade) have been very helpful so far, in that I've got 2-3 months to commision our system, and ourselves to provide a SLD etc. will advise as to whether we get full approval.

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ejrossouw commented · Mar 16 at 08:08 AM

@Tig 170 An ESS is not the same use case as a mobile system with AC ignore implemented. And off-grid system with a generator is a good example of the latter where you can e.g. turn on the generator when e.g. an overload occurs. The OP can in principle use the grid as a "generator" this way, but the recommendations is for him to engage on the topic with his DNO as it not an ESS and an exception to the rule with no valid testing procedure either.

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