Light touch enquiry to DNO for max potential PV export prior to making plans

[SunnyDevon]

I'd like to gain an idea of how to go about a likely yes/no/SIZE limit for a G99 application before I expend too much effort working out how to make the formal G99 application. In other words, Hello National Grid (our DNO) can I export something near to 50A from my address? Looking for any feedback, tips, opinions, experience of doing this.

 

We've a two year old house in an old cow field that has the benefit of a 3.6kw PV rooftop system from day one, we have an EV, Zappi & Eddi. It is my desire to triple our PV with a ground mounted array.

 

The planers have a home owner process - tell us what your intending and we'll indicate if your likely to gain planning.  They have stated that they are required to support green generation schemes as long as it's sensible. So that's good, I'm not going to run into a brick wall, I'd like to seek a similar indication from the DNO.

 

Attached, for interest, our planned PV location which is out of sight of the house and the very few neighbours.

 

 

 

[MikeSharp01]

Talking to people this seems like something of a lottery. Several here have asked for more than the 16A limit and got it while others did not. If you can get 3ph you will have 48A. We are about to ask for 7kW (32A approx) but my sources say we won't get it while another- who works for a DNO says is worth  punt.

[ToughButterCup]

I've asked a colleague - sparky - the same question: lots of tooth sucking.

 

 

PS, lovely house....

Edited February 3 by ToughButterCup

[Alan Ambrose]

It might simply depend on the state of your supply wiring close to your house. It’s a relatively new kind of query so may take you a while to find someone who know’s what you’re talking about. I think some here on BH have done their own formal application.

[SunnyDevon]

Thank you all, I suppose my key question is - does my DNO (NG down here in west Devon) have a light touch enquiry process. I assume there will be quite a lot of effort in the formal application, so I'm looking for a quick but simple response from them along the lines of possibly, probably, we won't know till we come and inspect, unlikely, no chance, following the first two I'd crack on and acquaint myself with making the application, the latter responses would probably lead to me saving the effort and reconsidering a way forward.

Thanks for reading this.

Edited February 3 by SunnyDevon

[Dillsue]

A G99 application is straight forward- download the form and have a look but there's a fee to pay.

 

Our DNO(SPEN) was happy to look at an informal enquiry and we agreed our export limit by email/phone and then did the formal application.

 

If you are tripling your array to 11kw remember that it's the inverters output you declare to the DNO, not the size of the array. You could hook up 11kw of panels to a smaller inverter and apply for the smaller inverters output. If you'll use all 11kw in the height of the summer then you could always go for an export limited system and do a G99/G100 application. That way you'll have the full 11kw available for self consumption but export as much or as little as your DNO will allow.

[SunnyDevon]

Thank you, yes I have become aware of inverter undersizing and limiting. Interesting SPEN accepted an informal approach initially, I wonder if anyone has had such an enlightened response from National Grid.

Edited February 3 by SunnyDevon

[Dillsue]

Not sure if NG publish such a thing but SPEN have online heat maps of their distribution networks showing where they have constraints for new connections(not domestic size systems) For each section of the network there's a contact email address so I just emailed that address and outlined what I had in mind. A junior engineer phoned me 2 days later, having already looked at the network serving us, and we agreed things over the next day or so. Formal application followed just to formalise what we'd already agreed.

 

If your looking primarily to maximise self consumption then you may be best to go for a big system with export limitation as pushing the full 11kw down a single phase is quite a big ask. Its difficult to see how NG could say no if you implement export limitation and are prepared to go to zero for the addtional array and exporting only the existing 16amp

Edited February 3 by Dillsue

[SteamyTea]

Call up National Grid (DNO) and ask to speak to the department that actually deals with PV installations, rather than just a general customer service department that will almost certainly say 'no'.

When I was dealing with them (Western Power back then, they were extremely helpful as it saved them bother in the long term.

Used to deal with a guy called Paul, at the main office in Redruth, next to the college.

[joth]

To ask the other question, do you have 3 phase? Or any of the agricultural buildings around you have it? This may allow 3x export without the need for a G99

 

[SunnyDevon]

@joth, 3 phase, unfortunately not.

@SteamyTea Simple phone call  - good idea, why not. Why wouldn't I have tried it? Well, I've never been here before 😉 so we'll give it a go.

@Dillsue good idea, I'll have a poke arround their web and see if there are some useful contact details. I don't see why exporting 50A is too controversial, it's a new grid connection with an incoming 100A fuse.

 

Why do I want to do this? Well I didn't want to get into this too deep but I'm happy to expose my insanity and have people with more experience correct my expectations.

 

We face south and have no shading, our measly 3.6KW PV system generates about 3.6MWh per year (nice correlation of numbers). The PV heats all of our hot water upboosted for 10 months of the year. We consumed 2.6MWh of generation and exported 1MWh last year. We've moved to Intelligent Octopus with minimum 6 hours at 7.5p/KWh and are waiting for our Smart Export to be set up at 15p/KWh. We are not wasting a lot of generation with an average spring or autumn day producing 800-1,200 W of generation with some overcast - great for the hot water and all the background loads - but it won't charge a car. I believe it's part of the Type 2 EV chagrining definition that the charger needs a minimum of 1.4KW else it stops charging. So picture a typical fluffy cumulous cloud summers day and our EV starts /stops / starts charging, its hopelessly inefficient. So for us to ride the peeks and troughs, car charging needs a system twice our size and to gain a reasonable charge triple our capacity would be good. We don't as yet have a battery (apart from the one with a wheel at each corner) and the builder kindly gave us an LPG boiler and tank. So clearly an Air or Ground Source heat pump is on the cards. We have a perfect site for a ground array (refer to initial post at the top) that we won't have to look at and panels are SO cheap, then there is the possibility zero VAT rating from the start of this month. Oh, clearly no FIT.

 

So with that bit of background there are two ways we can view our electrical setup.

 

A) Generate as much as possible, self consume as much as possible by car charging half the year and heat pump support for perhaps 3-4 months, always having enough generation for background loads on the glummest of days.

 

B) More realistically at the moment, consume all our needs time shifted from the grid off peak at 7.5p and export as much generation as possible at 15p. Should the great Octopus tariffs disappear, we could always fall back to A) above.

 

Either way why wouldn't I want to add a shed load of panels?

 

If you have made it this far, thank you 🙂

 

[Dillsue]

51 minutes ago, SunnyDevon said:

I don't see why exporting 50A is too controversial, it's a new grid connection with an incoming 100A fuse.

 

Incoming and outgoing capacity aren't the same. Fair chance you've already got the incoming voltage set fairly high to allow the DNO to get as much power round the grid without upping the current and requiring expensive bigger cables.

 

When you draw 50amps from the grid it pulls the voltage down which isn't a problem if you've already started with a high supply voltage.

 

When you try to export 50 amps it pushes the house voltage up and if your starting no load voltage is already high, your 50amp export will take the house voltage over the 253volt statutory limit. More importantly it might take your neighbours voltage over the limit which is a problem for the DNO.

 

If you're on your own transformer it may give you more options but anything shared or potentially shared in the future and your likely stuck with the DNOs std policies

Edited February 3 by Dillsue

[SunnyDevon]

@Dillsue most informative, thank you, there's always more to everything than initially meets the eye.

[sharpener]

I am on WPD as was and have 3.68kW of AC connected panesl and 3.24kW of DC panels all on a Victron 5kVA Multiplus II battery system.

 

On 03/02/2024 at 15:05, SunnyDevon said:

A) Generate as much as possible, self consume as much as possible by car charging half the year and heat pump support for perhaps 3-4 months, always having enough generation for background loads on the glummest of days.

 

WPD wanted me to restrict the generation capability of the inverter to 3.7 kW but that still leaves me free to charge the car at over 6kW when the sun is shining and the house battery is full.

 

Try ringing 01752 502021 and ask for Cerys Piper, she was most helpful in steering me to the right person. Or Alan Langman 01752 502260 who actually dealt with the case.

[Pocster]

Sleeping with your DNO doesn’t get you any favours either ( so my friend told me ) .

[SunnyDevon]

18 hours ago, sharpener said:

I am on WPD as was and have 3.68kW of AC connected panesl and 3.24kW of DC panels all on a Victron 5kVA Multiplus II battery system.

 

 

WPD wanted me to restrict the generation capability of the inverter to 3.7 kW but that still leaves me free to charge the car at over 6kW when the sun is shining and the house battery is full.

 

Try ringing 01752 502021 and ask for Cerys Piper, she was most helpful in steering me to the right person. Or Alan Langman 01752 502260 who actually dealt with the case.

Great, thanks for taking the time to respond. WPD, as in Western Power, now National Grid down here on the Devon / Cornwall border? Guessing so as that is a Plymouth number.

[sharpener]

Yes