'Off Grid' inverters and G99 certificates in UK

[jamiegreen]

Hi jamiegreen, where is that quote from?

DNO Permission for Solar PV

What are distribution network operators and when do you need DNO permission for solar PV? Find out the system size limits you need to know.

blog.spiritenergy.co.uk

I'm fairly set in my mind on with no back feeding to the grid and no load sharing between grid and inverter (simultaneously) then one would not need an application, but someone feel free to prove me wrong!

The grid is in a messy state right now, if possible, and that's a big if, tell them to do one and go completely off grid
albeit location is a factor, backup geni's are a real helpful addition, but if you live in the middle of town that might not be such a popular idea.. Without that its some careful load watching.

 

[shavermcspud]

You cannot connect any equipment that has the ability to feed back to the grid, be it software limited G100 or not in the UK without post install notification (under 3.68kW) G98 or prior approval G99 (greater than 3.68kW). The G99 procedure is there for several reasons, 1) for any equipment that has the ability to export over 16Amps per phase (limited or not) 2) you may be on a looped supply to your neighbour. 3) The infrastructure in place isn't capable of the potential feed back from a >16Amp per phase system, 4) and most importantly, your distance from the sub station/transformer maybe a fair distance and as such the center tap may have been adjusted to provide you at the end of the long cable run to be 230V, for your GT system to overcome this your output voltage has to be increased from your inverter which can cause even more issues for people closer to the sub station. As a registered UK Napit & MCS Solar PV installer, I deal with DNO's daily and these requirements are in place for a reason. If you need help with DNO applications, give me a DM and ill do it for you or guide you through it.
Please don't connect GT equipment without prior approval or notification, it can genuinely cause headaches for installers and DNO's alike.

 

[SenileOldGit]

Hi shavermcspud, can I connect hybrid inverters that physically can't feed back to the grid, without getting a G99? Can I connect a hybrid inverter that is set to not feed back to the grid, but is capable of doing so, without a G99? I have no intention of ever exporting anything to the grid.

 

[shavermcspud]

Hi shavermcspud, can I connect hybrid inverters that physically can't feed back to the grid, without getting a G99? Can I connect a hybrid inverter that is set to not feed back to the grid, but is capable of doing so, without a G99? I have no intention of ever exporting anything to the grid.

If your non GT inverter is type tested "https://www.ena-eng.org/gen-ttr/" have a search there, yes you can connect it. You cant however install a GT inverter with export capabilities regardless if disabled or not without prior permission.

 

[Steve Fractals]

Hi Steve Fractals, do you mean you are using an MPP Solar inverter? I think my electrician has wired up the consumer unit in the inverter box (the outside box I keep my inverters and batteries in) in the way you describe your set up. This may be why he has never mentioned DNO approval to me, I only found out about all of this after he had installed the inverters. I have two PIP5048MKX inverters that are each 5kW, so I have 10kW max output, and I have managed to overload the circuit breakers once, when I had a shower on, and two fan heaters, which went over the 10kW., but that's only once in four months.
The PIP5048MKX inverters cannot export to grid, but the Deye inverter I am thinking of replacing them with CAN export to grid, although this can be turned off in the settings, so how do I stand then, with the same consumer unit in my inverter box?

Yes I'm using a single PIP6048MT which is a 6KW and like our PIP5048 cannot export to grid.

If your grid input has been moved/reconfigured so that it's only job is to feed the inverters then even with the Deye (if it has a grid export off) it can't export as the AC-in shouldn't be bidirectional unless the option to export is on etc.

Not sure why you are thinking of changing over to the Deye unless your MPP inverters are faulty, what would the Deye give you that the MPP cannot?

 

[SenileOldGit]

Hi Steve Fractals, my MPP Solar inverters are faulty... see this (rather long) thread:

25kWh daily output, but I only used to need 10kWh per day.

I have just set up my first solar system, 12kW using 20 x Canadian Solar 595W panels, two MPP Solar PIP5048MKX inverters in parallel, and two Pylontech US5000 batteries (10kWh in total). I have been using the system for three or four weeks. My girlfriend and I built a ground mount using ground...

diysolarforum.com

I would much rather continue with the MPP Solar inverters (PIP5048MKX), but I'm waiting to hear back from their support (only three or four days' wait so far) for their final word on fixing them. The 8kW Deye inverters only offer 8kW of output, and since I can only afford one of them, I would have to set up bus bars for my batteries, and the Growatt SPF5000ES only has a maximum PV Voc of 450V, whereas the PIP5048MKX can take 500V, so I would have to remove one panel from each of my 10 panel strings to use the Growatts. (But they are much easier to fit, no need for any new cabling as there are two of them.)

 

[SenileOldGit]

I noticed that the ENA webpage says: "G100 details the technical requirements for customers' export and import limitation schemes applicable after 1 May 2023. These standards are available free from the ENA Document Catalogue."

Has anybody already downloaded G100 so I can have a look at it, without having to register on the ENA website? (They force you to make an account before you can view the document, which seems a bit daft to me.)

 

[shavermcspud]

I noticed that the ENA webpage says: "G100 details the technical requirements for customers' export and import limitation schemes applicable after 1 May 2023. These standards are available free from the ENA Document Catalogue."

Has anybody already downloaded G100 so I can have a look at it, without having to register on the ENA website? (They force you to make an account before you can view the document, which seems a bit daft to me.)

You don't need to register

Redirect Notice

 

[SenileOldGit]

Thanks for the link, shavermcspud.
A hypothetical question: say somebody was to install an inverter, and then apply for a G99, and eventually was refused. What happens then? Does the DNO come round to their house and demand to see their electricity meter, with the presumption that just because they have applied for a G99, they must have already fitted an inverter to their grid supply, even though they aren't supposed to? If this was the case, then presumably everybody who has ever applied for a G99 and has been refused would have had a visit from their DNO, accusing them of having installed an inverter without permission, even though the DNO can't have any evidence of this.
What are the legal ramifications of doing this? I presume there aren't any.
There must be hundreds of non-Type Tested inverters instaled in the U.K., with no G99 applied for. I've never read a news item about a DNO going round to one of their houses, nor of anybody being prosecuted for it.

 

[SenileOldGit]

ps I read in the G100 document something about if an inverter can both export and not export, that the ability to change this option must not be in the hands of the customer, but instead only the installer should be able to change this. The SunSynk/Deye inverters have a simple setting to change export on and off, so how have they got so many inverters that have passed Type Testing?

 

[SenileOldGit]

I am now thinking that instead of buying two Growatt SPF5000ES inverters for £2,600, I should buy two SunSynk Sun 5K Ecco Hybrid inverters, for £3,228, from here:

Sunsynk Sun 5K ECCO Hybrid Inverter

Shop Sunsynk 5kW ECCO hybrid Inverter to manage power flow from multiple sources | Dual MPPT | SolarMan App Compatible | From £1,057 +VAT

batteryfactory.co.uk

The Growatts can only accept 450V of PV input, and I would have to remove two of my twenty solar panels (which have a Voc of 41V) to use them safely, the SunSynk can accept 500V of PV input, so no need to change anything with my panels.
My electrician is going to fit an isolation switch for my current inverter set up soon, which will allow me to re-route the grid cables that currently go into my inverters, so that they bypass the inverters and go straight to my consumer unit - i.e. like it was before I got my solar system. I can then apply for a G99 for the two 5K SunSynks, stop using my faulty MPP Solar inverters (which are using more electricity than I used to use before I got them, due to power lost in the inverters themselves), then when my G99 has been approved, I buy the SunSynks and have them installed.

 

[shavermcspud]

Thanks for the link, shavermcspud.
A hypothetical question: say somebody was to install an inverter, and then apply for a G99, and eventually was refused. What happens then? Does the DNO come round to their house and demand to see their electricity meter, with the presumption that just because they have applied for a G99, they must have already fitted an inverter to their grid supply, even though they aren't supposed to? If this was the case, then presumably everybody who has ever applied for a G99 and has been refused would have had a visit from their DNO, accusing them of having installed an inverter without permission, even though the DNO can't have any evidence of this.
What are the legal ramifications of doing this? I presume there aren't any.
There must be hundreds of non-Type Tested inverters instaled in the U.K., with no G99 applied for. I've never read a news item about a DNO going round to one of their houses, nor of anybody being prosecuted for it.

It does happen and has in the past, G99 isn't a retrospective application, its prior approval before any kit is connected, remember the grid for all intense and purpose is a balancing act of Voltage & frequency, so the local operator knowing what is and isn't connected to sometimes aging head end kit is fundamental to the stability of the grid as a whole. Its not difficult for a local operator to see voltage rise due to inverter output, do a quick check and see who has registered for Solar PV and single out those that have just rigged it up anyway. The grid isn't owned by the end user and as such shouldn't be interfered with without following the procedures. To answer your initial question, they will visit and demand the system is removed, fines and confiscation have happened in the past. Type testing is there for many reasons, to make sure the equipment meets the regulatory needs for harmonics, voltage deviation, frequency output, shutdown speed for anti islanding along with many other technical factors. If you are physically going off grid and have no connection to the grid, connect anything you like up as it wont adversely affect anyone else bar you. Or just apply got a G99, its really not that hard to do and in 99% of cases you wont be refused or will be just asked to have an export limit fitted and witness tested. Simples

 

[SenileOldGit]

But since I won't be exporting any electricity, they will have no idea I have even installed the inverters, surely. If the 'zero export' function works correctly (which I assume it absolutely must, in order for the SunSynk inverters to be Type Tested) then there will be no evidence (and no problem either, by definition) for the rest of the grid. Why would somebody who hasn't applied for a G99 be intentionally exporting to the grid anyway? It makes no sense. So if inverters aren't exporting anything, there can be no way for anybody else to know that you even have them. I've searched Google for any incidents of anybody being prosecuted or having their equipment confiscated, and I can't find any.
I'm not disagreeing with your central argument though.

 

[shavermcspud]

As i said, I can only advise you, what you choose to do is up to you, I can't see why you're adverse to just applying for a G99, its totally free in most cases, you'll be legit and can export if you ever need to. Although your googling hasn't found you any online posts, its happened, I'm in the circle of installers, news letters and other groups and deal with the DNO daily and trust me it happens. In addition if you have a smart meter and no isolator after the meter, the second you remove the main cutout to install the sunsync from the meter tails, which you have to do for its bypass mode, your meter will flag this up as local meter power loss if its not a local power cut and localised to your meter only.

 

[SenileOldGit]

Hi shavemcspud, no worries, I do agree with you, I was just thinking hypothetically. I have a 70 year old meter, I wonder if they will insist on me getting a smart meter installed as part of the G99. I would much rather have it all done properly than have to worry about being cut off from the grid at some stage. Do you have any idea of approximately how long it would take me to get a G99 for two Sunsynk 5kW inverters? They are on the Type Tested list, I think it's model no. SYNK-5K-SG04LP1 that I am going to get.
I'm not sure what the difference between the Ecco and 'non-Ecco' models is, on this page:

5kw Hybrid Inverter | Sunsynk

www.sunsynk.org

the only thing I can see is that the Ecco model has a 'Meter port'. What does that mean?

One odd thing, on that webpage it says:

• Solar Input
  Max power input – 6500W
  Max V DC input – 370V (100V~500V)
  Max current input – 11A + 11A
  MPPTs – 2
  MPPT Range – 125~425V

Should 'Max V DC input' say 'Nominal V DC input'? Otherwise, why does it (100V~500V) after it, and why is the MPPT Range 125~425V?

And the Max current input says it's only 11A + 11A, but on this page:

https://portal.wholegreenrenewables.co.uk/reseller/docs/5kW%20ECCO%20Data%20Sheet.jpg

it says the PV Input Current is 13A, and the Max. PV Isc is 17A! (My Canadian Solar 595W panels have an Isc of 18A.)

 

[houseofancients]

If I have a Deye 8Kw inverter installed and then apply for a G99 (or whatever form it is), will my chances of approval be higher because I don't want to export anything to the grid? Hasn't anybody in the UK here applied for a G99 form?

deye should have that reg already .
use the sunsynk same model nr reg and you should be fine

 

[SenileOldGit]

Hi houseofancients, I've found all the SunSynk inverters on the Type Tested website, so I should have no problem applying for the G99, but thanks for the suggestion.

 

[shavermcspud]

Hi shavemcspud, no worries, I do agree with you, I was just thinking hypothetically. I have a 70 year old meter, I wonder if they will insist on me getting a smart meter installed as part of the G99. I would much rather have it all done properly than have to worry about being cut off from the grid at some stage. Do you have any idea of approximately how long it would take me to get a G99 for two Sunsynk 5kW inverters? They are on the Type Tested list, I think it's model no. SYNK-5K-SG04LP1 that I am going to get.
I'm not sure what the difference between the Ecco and 'non-Ecco' models is, on this page:

5kw Hybrid Inverter | Sunsynk

www.sunsynk.org

the only thing I can see is that the Ecco model has a 'Meter port'. What does that mean?

One odd thing, on that webpage it says:

• Solar Input
  Max power input – 6500W
  Max V DC input – 370V (100V~500V)
  Max current input – 11A + 11A
  MPPTs – 2
  MPPT Range – 125~425V

Should 'Max V DC input' say 'Nominal V DC input'? Otherwise, why does it (100V~500V) after it, and why is the MPPT Range 125~425V?

And the Max current input says it's only 11A + 11A, but on this page:

https://portal.wholegreenrenewables.co.uk/reseller/docs/5kW%20ECCO%20Data%20Sheet.jpg

it says the PV Input Current is 13A, and the Max. PV Isc is 17A! (My Canadian Solar 595W panels have an Isc of 18A.)

No, a smart meter isn't anything to do with the DNO application as thats down to your energy provider, as long as your main incommer, meter tails 16mm2 and upwards and fuse cutout are up to spec (80a+) you will be fine. Who's your local DNO, currently G99 take two days with UKPN under normal circumstances.

The max DC voltage before damage is 500V working range is between 125V and 425V, id aim for somewhere in the middle for better winter start up time. I wouldn't worry too much about the panel output compared to the max working current of the inverter. its the total string voltage per tracker you dont want to exceed

 

[SenileOldGit]

My DNO is NationalGrid, according to https://www.energynetworks.org/customers/find-my-network-operator

I am now thinking about going for an 8kW SunSynk inverter, rather than two 5kW SunSynk inverters. The 8kW allows 28A Max PV Isc and 22A PV Input Voltage,, and since the 5kW only allows 17A Max PV Isc and 13A PV Input Voltage, I don't expect I'd get more than 8kW PV from my 12kW solar panel array with two 5kW inverters, would I?

I had no idea a G99 would take two days, I thought it was four to six months!

 

[houseofancients]

Hi houseofancients, I've found all the SunSynk inverters on the Type Tested website, so I should have no problem applying for the G99, but thanks for the suggestion.

be sure to use the type number e.g. sun-5k...
and dont mention the brand..