Large arrays / NC7 applications

I bet this is harmonics related… I was initially offered 7kVa MEC due to harmonics. Once I escalated, I got passed from a nice but slightly clueless grad hire to the boss man who re-did the harmonics analysis and showed that I could go ahead.

Is there anything I'd need in relation to harmonics questions before they call? Tech docs for inverters I'm guessing but how do they calculate?

2 x Solaredge SE6000H Screenless.

Installer was back onto his networks contact and apparently it's harmonics all right, that I've to argue my case.

There's two houses down my laneway fed off a three phase line, hard to see how the harmonics are bad?

@randombar type tested data up to the 40th harmonic for the SE6000H attached. You'll be able to get this across the line, but you'll have to argue. They have assumed that your inverter exhibits the maximum harmonics allowable to comply with EN61000-3-12. You can now show that the inverter exhibits much lower harmonics as certified by the type test attached. They can now use this info to reevaluate harmonic limits.

Any luck ?

"seemed open to investigate further" - That's the stuff. They'll sort you out as best they can now I'm sure.

The paragraph/screenshot isn't loading there. What's xx that they're looking for?

apologies

what figures do they use to test off g5 and what’s the equivalent equation?

The latest:

======================================================================

======================================================================

So to progress any application they have for accepting their Inverter we need a Type Test confirming that it conforms to EN 50549 – conforming to EN 50539 automatically means that it meets EN 61000 requirements, and that the Rsce to be used is 33.

IF they want to have a lower Rsce used then they need to get a Type Test to EN 61000-3-12 (which goes up to 50kVA 3 phase) showing that the equipment has been validated at a lower Rsce, or that it is within limits at a particular short circuit level (Psc). These calculations are done by the Type Test Laboratory and need to come from the Type Test Lab.

However, every Inverter sold in Ireland to date has a Rsce of 33, so it may not be a problem for them to run with the standard.

There was some mention in the installers letter which seemed to indicate that they felt that a lower Rsce would allow a higher MEC – the Rsce relates to the maximum size of generator which can be installed, not to what it can export. The only relationship with size of MEC is that if you are limited in what you can install then this obviously limits what you can export.

In the attachment SE-Emissions they list compliance with EN 61000-3-11 and EN 61000 -3-12 for a number of Three Phase models,  which is fine, but there are other tests in EN 50549 which is why a Test Cert for EN50549 is required. Also this attachment did not reference single phase models.

As EN 50549 is a European standard I would expect that if Solar Edge are selling anywhere in the EU they should already have an EN50549 Test Cert.

In relation to the documentation submitted, they have provided a Test Cert for the UK G99, but this is Ireland so our requirements are different. Essentially conformance to EN 50549 means that most of the tests required in UK G99 were already done when the unit was tested to EN 50549. Similarly EREC G/5 is a UK standard and not relevant to Ireland.

A point for them to note is that the Protection Settings for Ireland are different for the UK so that the protection values shown on the UK G99 cert are unsuitable for use on ESB system.

The Test Cert supplied from Israel showing conformance to EMC requirements under EN 61000 – 6 is not of relevance to ESB – any standards to which the unit must conform are in EN 50549 and in the ESB Distribution Code.

======================================================================

======================================================================

Gone back to them with the following:

So to progress any application they have for accepting their Inverter we need a Type Test confirming that it conforms to EN 50549 – conforming to EN 50539 automatically means that it meets EN 61000 requirements, and that the Rsce to be used is 33.

Response: Please find Type Test confirming that it conforms to EN 50549 attached.

IF they want to have a lower Rsce used then they need to get a Type Test to EN 61000-3-12 (which goes up to 50kVA 3 phase) showing that the equipment has been validated at a lower Rsce, or that it is within limits at a particular short circuit level (Psc). These calculations are done by the Type Test Laboratory and need to come from the Type Test Lab. However, every Inverter sold in Ireland to date has a Rsce of 33, so it may not be a problem for them to run with the standard.

Response: I have attached type tested data up to the 40th harmonic for the SE6000 including Limit in BS EN61000-3-2 in Amps, these calculations were done by the type test laboratory and came from a type test lab.

There was some mention in the installers letter which seemed to indicate that they felt that a lower Rsce would allow a higher MEC – the Rsce relates to eth maximum size of generator which can be installed, not to what it can export. The only relationship with size of MEC is that if you are limited in what you can install then this obviously limits what you can export.

Response: My understanding is having a lower Rsce would give me a higher Harmonic limit, and as I am applying for the Export Limiting Scheme I believe it is this harmonic limit that is used to determine my MEC "the most onerous"

Basically, it comes down to this:

Rsce <33 is outside the scope of the EN 61000-3-12. This basically means there is a grey/undefined area in the overarching EN 61000 standard when it comes to the connection of distributed energy sources to Low Voltage Distribution Networks.

ESB Networks seem to have recognized this, so they instead have developed a policy that allows manufacturers to state compliance with EN 61000-3-12 harmonic limits at Rsce levels < 33. However, manufacturers and type-testers do not test for compliance with the limits down to lower levels of Rsce precisely because that falls outside of the scope of the EN 61000-3-12 standard and because other DSOs apply alternative methodologies to plug the gap/grey area like EREC G5, and the Western Power Networks policy attached above.

I'd really like to get the Irish Solar Energy Association involved on this one, because otherwise there's a de-facto ban on higher (but not unreasonable) levels of solar inverter connection at the LV network even though the equipment would technically comply with all relevant harmonics standards quite easily.

Ya this does seem to be a bit crazy, how does anyone get an NC7 so in that case??

@randombar I have fired off a quick email to the Irish Solar Energy Association to see if their grid working group would be interested in engaging with ESBN on their harmonics policy. It irks me that people are still encountering this based on an antiquated standard.

If they come back to me, would you be interested in providing further details/specifics? Such as who your installer is etc.

Anybody else with NC7 experiences of the same too, would be good to present more data.

It's such a silly blocker and nobody is seeking the watering down of grid standards. But the current interpretation of the EN 61000 standard means you basically need an MIC>= 1.75 MEC at all times on a harmonics basis, which is nonsense.

Hi everyone,

Posting here as it was recommended I pop over from my own thread.

I'm hoping someone can offer some advice as I'm
trying to complete the Micro-Generation Installation Confirmation
Certificate myself and am a bit stuck.

For context, I had a
disagreement with my solar panel installers (explained in a previous
thread) which thankfully resolved with them agreeing to cover the NC7
costs and me taking over the application.

Now, the ESB requires
this certificate (FORM NC7-01-R1) and there's a section regarding grid
protection settings with boxes to confirm compliance. I'm unsure how to
check if my Solis S5-EH1P6K-L inverter meets these specific settings
before sending it back to them.

I apologise if this is a basic question, but I'm out of my depth. Any
guidance on how to check if my inverter aligns with these settings
would be greatly appreciated.

Thanks in advance!