Getting started on the PV G99 (and G100) minefield

[dnb]

I would like PV on the roof of my new build. I believe I can easily fit 20 300W panels on the main roof (and I am considering an additional 4 on the SE side of the house). The snag is that I am in a very rural location served by a single phase wire that already has a lot of PV hanging off it from other houses. I already have a 100A supply to site from the house I demolished (parked in a box at the site entrance). Looking on the map SSEN provide, all the transformers in my area are marked red - presumably meaning they're close to their limits. So my large scale PV system is going to meet resistance (pun intended) from SSEN. Apparently I need to make a G98 or G99 application now, not a G83 etc as these are about to be superseded. Practically this seems to change little if I only want to export 3.75kW, other than a bit more detail seems to be required and there is the chance of them saying that I can't. It looks rather more complicated if I want to try to export more and I expect it to be very costly too.

 

So the question is what G100 compliant kit is out there?  Is there a nice 6 to 8kW single phase inverter that will monitor output, switch on loads (eg immersion heaters) and throttle output based on "spare" power the house can't currently use (even after all the loads are on) that has the right paperwork so I can put it in my application to demonstrate compliance with whatever power they will let me export? It seems to me that this is quite a new standard so compliant parts are not common yet.

 

[dnb]

Nothing like answering your own question...  Is the Solis 6.0kW 4G Dual MPPT any good? It seems to be "about right" for my 20 panels if I stick to this, but I haven't found much information yet about how it is monitoring output except that it's by current clamp. So it could be a fun game trying to work out if the inverter has backed off generating or the sun has gone when it comes to deciding to switch in loads for self consumption.

[DamonHD]

G83 and G59 were replaced by G100 and G99 on 2019-04-27.

 

I'm not sure if the DNO will accept any of the throttling kit, as opposed to disconnecting, but I'm be pleased to be wrong.  If it will then there is also stuff such as the (new) Enphase that can also auto-island and form a mini-grid balancing generation within the house, and brands such as Outback, and SMA's Sunny Island (though I have heard lots of complaints about SI).

 

Rgds

 

Damon

[ProDave]

One thing to bear in mind is they will expect the inverter to be G100 or G99 compliant.  This might prevent you for instance picking up a G59 complaint inverter cheap from ebay as the DNO could be awkward and say no to it,.

 

You can still install up to 3,68Kw and notify them afterwards, but if you want more you must apply.  It sounds like it would be worth applying to see what they will allow and what the costs are.

[dnb]

Happily the inverter I referenced is g100 compliant if I get the latest version.  The older ones are apparently not.

I do intend to apply to see what i will be allowed but I am not hopeful.

[dnb]

Application is submitted now, so we'll soon see what SSEN will let me have. Anything over zero makes the plan work.

[Dan F]

I'm also in a SSEN area.  Out of interest which application did you submitin the end?  G98, G99 or G99 fast-track?

[Dan F]

On 24/02/2020 at 07:36, DamonHD said:

I'm not sure if the DNO will accept any of the throttling kit, as opposed to disconnecting, but I'm be pleased to be wrong

 

It seems that's what G100 is all about. I beleive that this is now allowed as long as your inverter supports G100 compliant ELS (export limiting scheme).

https://www.energynetworks.org/electricity/engineering/distributed-generation/engineering-recommendation-g100.html

[dnb]

9 minutes ago, Dan Feist said:

Out of interest which application did you submitin the end?

I think it was a g98. But it isn't totally obvious from their website other than specifying microgeneration with less than 17A per phase.

[markharro]

Can anyone offer a simple explanation of G100 and G99 for a complete numpty? We are planning a 10+kW installation and I am really struggling to understand the export rules and processes and potential costs etc. Thanks

[Smallholder]

I realise this is an old thread, but for anyone else wondering about G99 and G100 forms...

 

G99 seems to be needed for proposed grid connected power generation systems up to 50kW and G100 for over 50kW.

 

So almost all of us will be looking at G99 forms.

[Dillsue]

10 hours ago, Smallholder said:

I realise this is an old thread, but for anyone else wondering about G99 and G100 forms...

 

G99 seems to be needed for proposed grid connected power generation systems up to 50kW and G100 for over 50kW.

 

So almost all of us will be looking at G99 forms.

G98 is a notification for micro generation less than 16 amp(3.68kw) per phase

G99 is an application for micro generation greater than 16 amp(3.68kw) per phase

G100 is for export limition as a supplement to G99 if the DNO requires it

 

I suspect most installs will only require a G98 notification

Edited April 4, 2023 by Dillsue

[MisterB]

On 04/04/2023 at 06:54, Dillsue said:

G98 is a notification for micro generation less than 16 amp(3.68kw) per phase

G99 is an application for micro generation greater than 16 amp(3.68kw) per phase

G100 is for export limition as a supplement to G99 if the DNO requires it

 

I suspect most installs will only require a G98 notification

 

Can anyone advise me on which application i need to make please, UK Power Networks werent particularly helpful when i said i wanted to submit my own application, I was told i MUST use an MCIS qualified installer. When i challenged her and told hew i would be using a competent and fully qualified electrician for the installation, she didnt seem best pleased for some reason?

 

Anyway, the electrician i am going to use (who we use for all our electrical work) has no experience in submitting the forms, so i said i would do them. 

 

To explain what i have and intend to have is this, i already have a 4kw PV system installed under the FiT scheme and MCIS installed, so i am not looking to ammend that in any way and potentially impact or lose those payments. i am looking to install an 5KW ECCO Sunsynk hybrid inverter and 28.6kw of battery storage ( 2 x 14.3 Seplos 280 L upright cases from Fogstar) that i can charge during the off peak rates 0030-00430 in the winter and the solar in summer. we are all electric and have Dimplex Quantum storage heaters. 

i have spoken to Sunsynk and the inverter is suitable for my setup and will be set to zero export to the grid and will get close to fully charging my batteries overnight. The inverter is on the approved list.

 

My question and the help needed are as follows

 

1 Am i right in saying i can use a competent and qualified electrician rather then MUST use an MCIS registered installer?

 

2 As my 'add on' system will not feed back into the grid, is it a G99 application or a G98 notification i would need? i suspect its a G99 as its more than 3.68kw, assuming that refers to the inverter NOT the storage, albeit it wont be feeding back to the grid.

 

My confusion is with the term micro generator - the inverter isnt a generator (is it?) and neither are the batteries?. The only generator are my PV panels and inverter already installed, or is this just a 'catch all term'. 

 

if anyone can offer any advice on completing the correct paperwork, or which parts i need to complete (Part 4?) then that would be extremely helpful, even better if someone could share their application made under similar circumstances. 

 

i'm not trying to fight a crusade but i get irritated when i am told i cant use a competent, qualified electrician to install electrical equipment - it reminds me of the old CORGI regime who turned their scheme into their very own thiefdom ......

[kommando]

The existing G98 covers the first 3.68Kw, this is the inverter capacity not the panel capacity as the inverter is an AC generator and the panels make DC. DNO does not want or need to know about DC generators only AC generators. So your new Sunsynk is an extra AC generator, even if set to nil export it will take you over the G98 into G99 as a potential nil export control failure could allow an export of over 3.68Kw. As the Sunsynk has the G99 cert then you have the option of a G99 Fast track application ie no need for attended testing of nil export controls. Regardless of a full G99 or Fast track G99 you have to have permission before any connection. 

[Rob99]

If you want to do the application yourself then UKPN have an online process called Smart Connect which you can sign up to as a homeowner.

It does say on there that, provided you answer the questions and submit the correct information online then you should get an automatic approval for up to 5kW connection to the grid.

In your case, as you already have a FIT export in place it's possible you won't get automatic approval but worth a try anyway.

[DamonHD]

You should (must) talk to whoever administers your FiTs before making changes to anything involving microgeneration or electrical storage.

Edited July 28, 2023 by DamonHD

[Dillsue]

6 hours ago, DamonHD said:

You should (must) talk to whoever administers your FiTs before making changes to anything involving microgeneration or electrical storage.

That's only the case if youre altering the FIT accreditted system. If youre adding a second system, as the OP is, it doesnt alter the accreditation of the FIT system so no interaction with your FIT payer is needed.

 

Different matter with the DNO who has to preapprove  anything more than 16amp potential export, with potential being the important bit. Whilst you can say your battery pack is set to zero export,  your DNO will likely need proof. In our case SPEN told me it would be £350 to come out and witness the export limitation was actually compliant with G100. That's on top of the G99 fee.

 

No need for an MCS install to connect to the grid, just a part P spark

 

 

Edited July 28, 2023 by Dillsue

[DamonHD]

Thanks for the correction!

[Dillsue]

7 hours ago, DamonHD said:

Thanks for the correction!

You're welcome.

 

Even with a FIT system you can chop and change pretty much what you like since OFGEM changed the FIT scheme rules 18 months ago. You can change components not like for like, increase or decrease capacity and add batteries with some restrictions. About the only thing you can't do is move a system to another property. If you add capacity you only get paid for the original accreditted capacity. Once youve changed stuff just let your FIT payer know

[magnayn]

On 30/07/2023 at 17:18, Dillsue said:

You're welcome.

 

Even with a FIT system you can chop and change pretty much what you like since OFGEM changed the FIT scheme rules 18 months ago. You can change components not like for like, increase or decrease capacity and add batteries with some restrictions. About the only thing you can't do is move a system to another property. If you add capacity you only get paid for the original accreditted capacity. Once youve changed stuff just let your FIT payer know

 

OOh - that's useful information!

 

Curious how this works in practice. I have 16x250W (4000W) panels; if I replaced them to effectively double the output (and appropriate inverter, DNO approvals, etc) would my FIT payments effectively have to be half what the generation meter says ?

 

 

[Dillsue]

2 hours ago, magnayn said:

would my FIT payments effectively have to be half what the generation meter says ?

 

Exactly that. They'll only make FIT payments on the FIT registered capacity which for you is 4kw. If you double the system size to 8kw then paying for 50% of your generation is paying only for 4kw of generation