G99 refusal. G100...where do I go from here?

[jimseng]

I have just received this email from National grid regarding my G99 application. I am new to this and this is a self install so please be as clear as you can be.

 

"I have just run the model for [my address] whilst the full 10kW is OK to connect via a G99 compliant device any exportation from site would need to be limited to 2kW via a G100 complaint device. If you are happy to proceed with the limited system please let me know along with the make model and ENA data base reference of your proposed inverter and I will send the relevant letter.

 

To allow the exportation of the full 10kW then the local network would be required to be upgraded and the end-user would be expected to contribute to these works and I would estimate these costs could be in excess of £5000.00"

 

So I am installing 10.2k solar on the roof and was planning on a Victron Multiplus 10k inverter. They are able to limit the export but I don't believe Victron deem it commercially viable to get them G100 certified (I am at the limit of my understanding here and I was waiting for the G99 application to go through before proceeding). 
My plan is to have as much battery storage as I can afford, perhaps 1 or  maybe 2 Fogstar 16.1kWh batteries and I went for a 10kw inverter as it seemed about what would comfortably cover most of my energy demands without being too OTT. 
So what next. I am familiar with Victron kit but I don't really care what I install. If I were to install a Victron Multiplus then can I install a device between the meter and the inverter that satisfies the G100? or is it cheaper / should I be looking at an inverter that will satisfy National Grid? Please bear with my while I try and catch up on this. 
My original plan was solar PV, mppt, batteries, inverter. I don't really care about exporting as I don't think I would earn much without paying for an  MCS install and I think I can divert the energy to the farm if I have too much (unlikely).

Thanks

Matt

 

[MikeGrahamT21]

You'll need a G100 compliant inverter, some of the Solis ones are properly compliant. There are also export power managers which sit seperate as the G100 device, Solis also do one of these, but i'm not 100% how they work, as i don't have/need one. They'll probably enforce this too, so they'll come out and do a compliance check.

[ProDave]

 Apply for G98 export limited to 16A (3.68Kw)  you can even notify after connection and it cannot be refused.

 

You just need to find an inverter that will deal with your panels and battery but is limited to 16A export and G98 certified.

[-rick-]

11 minutes ago, ProDave said:

 Apply for G98 export limited to 16A (3.68Kw)  you can even notify after connection and it cannot be refused.

 

You just need to find an inverter that will deal with your panels and battery but is limited to 16A export and G98 certified.

 

The multiplus models don't have built in solar MPPTs so the amount of solar connected to them is disconnected from their size. So could easily get a G98 Multiplus with lots of solar. Would be limited to 16A from the solar for house use + export though so guess you'd want big batteries to spread the solar over 24 hours. Most houses will only very rarely draw more than 16A (unless you use an electric shower or electric resistance heating/immersion. Could also look at whether some loads (immersion, maybe lighting) could be run straight off the battery.

 

You could potentially get a second inverter that was set to zero export, but the way Victron works AFAIK you wouldn't be able to share the battery so it would be a bit tricky and I'm not sure about how that works with the DNO approval.

[Beelbeebub]

As Pro Dave

 

I thought you can always get a 16A, 3.7kw export - and they will upgrade if required (which it seems might be the case)

 

As PD says, a compliant inverter may be the better route

 

I have 11kw of panels and use a Solax IES 8kw, with a 3.6kw export limit. It has 3 MPPT inputs so you can have 3 separate arrays.  The export limit is adjustable in software so if your limit is upped in the future you can up your export.

 

It seems a good bit of kit, the only downside is that it uses it's proprietary modular batteries which aren't as cheap per kwh as the fogstars and each 8kw inverter is limited to 20kwh storage - so you would need 2 inverters to get the equiv storage.  They do connect together to cooperate.

 

IRRC the inverter is about £1200 and each battery module (5kwh) is similar 

[JohnMo]

1 hour ago, Beelbeebub said:

proprietary modular batteries

Or you can always go AC coupled instead.

[jimseng]

I don't think 3.6kw is enough so right now I believe G98 isn't going to work for me. I only have electric,  for heating, hot water, MVHR and cooking so I will go over 3.6kw at the drop of a hat. I had thought of two inverters, the Victrons can run in parallel as far as I have seen. So I think it is either a G100 compliant inverter or an external G100 device, if anybody here has experience of these. I really don't want to be tied down to propriety batteries either. I have thought about having one inverter non grid tied for running specific items such as immersion or heat pump, perhaps with a changeover option. It is very frustrating as the farm paid 12k for an upgrade to the infrastructure a few years go and they seem to have been very short sighted and installed the minimum. 

[-rick-]

8 minutes ago, jimseng said:

I don't think 3.6kw is enough so right now I believe G98 isn't going to work for me. I only have electric,  for heating, hot water, MVHR and cooking so I will go over 3.6kw at the drop of a hat. I had thought of two inverters, the Victrons can run in parallel as far as I have seen. So I think it is either a G100 compliant inverter or an external G100 device, if anybody here has experience of these. I really don't want to be tied down to propriety batteries either.

 

If you pair two Victron inverters they share configuration and restritions, but two independent inverters (one behind the other in series), one g98 compliant set to export and one set to not export at all might be an option (but check the technicalities on this) but again if they are running seperately they couldn't share a single battery pack.

 

8 minutes ago, jimseng said:

I have thought about having one inverter non grid tied for running specific items such as immersion or heat pump, perhaps with a changeover option.

 

If you have a heatpump for heating and hotwater, unless you have a really big one 3.6kw should be enough for most of the time, a 10kw heatpump will draw less than 3kw most of the time. Cooking is spikey so when you first turn on an oven or hob it draws a lot, but once things are up to temperature the usage is relatively low.

 

 

8 minutes ago, jimseng said:

It is very frustrating as the farm paid 12k for an upgrade to the infrastructure a few years go and they seem to have been very short sighted and installed the minimum. 

 

Or maybe others have since used whatever spare they added, or there were multiple limitations and they fixed one enough for the farm but others are still in the way for you.

[Dillsue]

If youre not bothered about export why cant you select another inverter with a G100 cert? You can have your 10kw array and batteries but not the un certified multiplus.

 

I beleive you can get third party G100 devices to sit between an uncertified inverter and the grid but I don't think they are cheap and there's a good chance your DNO will want to witness test something that's not mainstream, at further cost!!

[jimseng]

15 minutes ago, Dillsue said:

If youre not bothered about export why cant you select another inverter with a G100 cert? 

I guess that is part of this question. There are some many inverters on the market and G100 certification doesn't seem to be top of the spec list when searching. I suppose I am looking for recommendations, with the proviso that I would like to choose my own batteries, probably in the nominal 48v voltage range given that I am looking at the Fogstar range. With 24 solar panels I suppose that is 3 strings of 8 or two strings of 12. 

I'm completely open to suggestions. My searches so far have left me a bit bewildered by choice with no experience of any make other than Victron kit at the 12v end of the market. 

[Dillsue]

The ENA type test register allows you to filter by G100 device to that's worth having a look through

[jimseng]

10 minutes ago, Dillsue said:

The ENA type test register allows you to filter by G100 device to that's worth having a look through

That is a handy tip indeed!

[Dillsue]

44 minutes ago, jimseng said:

That is a handy tip indeed!

Don't get too excited as I think that filter is for standalone devices only, not G100 certified inverters!