Semi Off-grid?

[lovo]

Hi All

 

Here in N.I. we can currently only connect a maximum of 4kW of PV to the grid.

 

I don't want to go fully off-grid but I do want more than this. Has anyone here heard of or installed a mix of circuits, some supplied only by a PB/battery and some directly by the mains?

 

Thanks

 

 

 

 

[billt]

It's possible - anything's possible but it's definitely not worth it unless you like a challenge and messing with this sort of thing, and probably not even then.

 

Are you sure that there's a 16A (4kW) limitation?

 

http://www.nienetworks.co.uk/Connections/Generation-connections/Small-scale-generation

says that up to 20kW single phase or 5MW three phase is possible.

 

If it's like the rest of the UK you can connect up to 16A per phase without getting prior authorisation, anything more needs permission, which may be the source of the claim.

 

[lovo]

@billt Yes, I believe its actually an export limit. You could theoretically have more as long as you never exported more than 4kW back to the grid. So say you had a hen house that constantly consumed 10kW's then you could put in a 14kW system.

 

Thanks

 

 

[dogman]

I have been looking at this issue as my array will have about 6Kw. my Solar man has given my options.

 

Apply to export more. In the uk with SSE it cost £300 to apply If they say no you then can add a limiter to ensure you never export more than 4kW costs about £170 to do this.

 

[lovo]

Thanks @dogman  We only have one supplier to export to over here - NIE. They are not exactly the most helpful bunch. Where does your excess generation go when the limiter kicks in?

 

 

[dogman]

Due to only having electricity at our site it will never really get to that as we have a diverter.

 

it is more that the electric company want to ensure you cannot.

 

The advantage as my Solar man tells me is that the equipment fitted to do this will send it somewhere else such as batteries. He is trying to sell me a system that can daisy chain batteries depending on your excess produced. Apparently they are about the size of a Desk top hard drive and you add to them as needed.

 

Probably wont yet as i have an old Immersun that will divert it to heat water.

 

however if you do produce to much and cannot use it its lost somehow by the inverter

[lovo]

We have a Solar iBoost in current house that does the same thing. I guess a lot of us are waiting for a battery that makes economic sense still.

 

Thanks

 

 

[Declan52]

58 minutes ago, lovo said:

We have a Solar iBoost in current house that does the same thing. I guess a lot of us are waiting for a battery that makes economic sense still.

 

Thanks

 

 

If you have a look on the green energy stores Facebook page they do the type of battery storage system you are looking for. They are based in newtownards. They give a rough cost of £6500 so it's not cheap. Read some of the comments about the length of time to break even. I got £85 back from my exported electric this year so payback is 76 years!!!

 

Edited March 6, 2017 by Declan52

[lovo]

Thanks @Declan52 , I'll take a look.

 

L.

 

 

[Crofter]

@lovo If you are facing an export limit per install, what would be involved in setting up a second, separate, connection/installation?

[lovo]

@Crofter No idea, but sounds messy. It's crazy that the utility companies can try and stifle renewables like this.

 

Thanks

L.

 

 

[SteamyTea]

The export limit is there to stop over voltage on local network, nothing to do with stifling innovation.

If too many people had high capacity systems, too close to each other, the voltage would rise above the maximum threshold.  There is then no choice but to automatically disconnect those systems.  No one is a winner then.

[lovo]

Call me a sceptic but I don't believe thats their only motivation. My neighbour has an 8kW system installed a few years ago before they brought the limits down.

 

 

Edited March 8, 2017 by lovo

[Jeremy Harris]

Our experience with SSE was that there was no charge for the request to fit a G59/3 PV system of more than 16 A per phase (and it's a current, not power, limit, with the closest approximation to power being 3.68 kW, but this is local grid voltage voltage-dependent).  They granted me permission to install a G59/3 system (~6.25 kWp) very quickly and with no hassle.

 

Here in the rest of the UK a system that doesn't require prior DNO approval can be installed under G83/2, in NI the standard is still G83/1.  NIE still allow a three phase, 16 A per phase, connection under G83/1, so roughly around 11.04 kWp of installed capacity.  Note that the limit is technically the installed capacity, and that NIE are clear that it is the inverter current limit that defines this, not the panel peak capacity.  As long as the inverter is set to limit at 16 A per phase (as all G83/1 inverters should be) then you can install as many panels as you like, within the voltage limit of the inverter DC MPPT input(s).  It can be useful to over-size the PV array and limit using the inverter, in terms of getting a longer period of useful generation through the day. 

 

Finally, many inverters (I suspect most, now) will soft limit at 253 V rms on the grid side.  Ours does this in summer, and all that happens is that the exported power is gradually reduced as the inverter holds a steady 253 V rms at it's grid connection terminals.  If you have a high grid voltage (as we do) then this caps your export without needing any intervention by anyone.

Edited March 8, 2017 by JSHarris

[lovo]

5 hours ago, JSHarris said:

As long as the inverter is set to limit at 16 A per phase (as all G83/1 inverters should be) then you can install as many panels as you like, within the voltage limit of the inverter DC MPPT input(s).  It can be useful to over-size the PV array and limit using the inverter, in terms of getting a longer period of useful generation through the day. 

 

 

Thanks @JSHarris. If we put in say 8kW system how would an inverter keep the export down to 4kW and what would it do with the extra? 

[Jeremy Harris]

If you can find a G83/1 inverter that will accept around 32 panels at the DC input (assuming around 250 Wp/panel), then what would happen is that the inverter would start up earlier and shut down later each day, and so increasing the duration, but not the magnitude, of PV generation.  There would be no excess, or extra, this would still be (under NIE rules) a 16 A, G83/1 installation.  Similarly, you would only ever be able to self-consume up to the limit of the inverter, so 16 A at whatever the grid voltage happened to be at that time.

 

Off the top of my head I'm not sure if there are any G83/1 inverters that can accept 32 panels at the DC side, but there may well be, as a lot of inverters are pretty flexible and programmable, so it's possible that there is a higher capacity inverter than can be programmed to work as a G83/1 one, during installation.

[jack]

5 hours ago, JSHarris said:

Our experience with SSE was that there was no charge for the request to fit a G59/3 PV system of more than 16 A per phase (and it's a current, not power, limit, with the closest approximation to power being 3.68 kW, but this is local grid voltage voltage-dependent).  They granted me permission to install a G59/3 system (~6.25 kWp) very quickly and with no hassle.

 

 

We had a similar experience with SSE about 18 mths ago - no charge for applying (as far as I can recall), and approval for 8.5kW without question.  

 

It did take them a long time to process the application though.  Their estimate was something like a month but it took more like 10 weeks from memory.

 

For reference, we have one 3-ish kW array a couple of doors up from us, on a split E-W system due to their roof layout.  I'm not aware of any others in the immediate vicinity, which undoubtedly was a factor in the approval.  

[lovo]

Thanks guys.  I don't think NIE must be open to applying for these bigger systems, but hopefully someone can prove me wrong - anyone from Northern Ireland been able to do this since the 4kW limit came in?

 

Thanks

 

 

[Jeremy Harris]

28 minutes ago, lovo said:

Thanks guys.  I don't think NIE must be open to applying for these bigger systems, but hopefully someone can prove me wrong - anyone from Northern Ireland been able to do this since the 4kW limit came in?

 

Thanks

 

 

 

 

Reading the NIE website, it seems that the rules are much the same as here in the rest of the UK, with a G59 system being allowed in much the same way, except they do it through a staged proposal system, so you would need to make an application for phase 2 of the approvals that are being given: http://www.nienetworks.co.uk/Connections/Generation-connections/Small-scale-generation

 

You can fit up to a nominal 11.04 kWp under G83/1, though, as long as you don't exceed 16 A per phase (the G83/1 limit).

Edited March 9, 2017 by JSHarris

[Declan52]

I think somebody on Ebuild had trouble getting PV installed because of where they lived in NI was rural so their network couldn't take any more connections. I am not sure but I think it might have been @slidersx200 who has built in saintfield.  I remember looking at a map showing the areas where there was still room when I put mine in. 

There was a vast uptake of the free PV systems here which has overloaded what is mostly a rural network.

Edited March 9, 2017 by Nickfromwales
Add @ for username ;)

[Calvinmiddle]

Yes I remember there being a NIE heat map showing capacity on the network.  If there wasn't then they wouldn't allow you to connect to the grid no matter what the size of the system was.

 

That was a couple of years ago - so will have a look for the link and post if I can find it.

[Calvinmiddle]

I think this is it

http://www.nienetworks.co.uk/Connections/Generation-connections/Small-scale-generation/11kV-Network-Heat-Map

[lovo]

@Calvinmiddle Thanks for the info.