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dnb

Getting started on the PV G99 (and G100) minefield

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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 Apparently I need to make a G98 or G99 application now, not a G83 etc as these are about to be superseded.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.

 

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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.

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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

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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.

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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.

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

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

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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

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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.

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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

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