System voltage Solar MPPT

[1Sparky]

Hey guy's and gal's,

A client had purchased an off grid package - 5kW MPPT Solar inverter - (Charge controller, Mains charger, Inverter all in one), 300Ah Lead Acid storage - 48v, 9 ODA380-36-M 380w solar panels - 3 per string. What determines the system voltage - My interpretation is the Voc of the array plus the bit extra worked out for temp. compensation of the lowest expected temp. With the formula @ 4.2 in AS/NZS 5033:2014 A1+A2. In this case around 150VDC. And being such falls into LV so requires earthfault monitoring of the panels etc. which this particular Solar Inverter is incapable of.

The Seller is trying to tell me that it is ELV because when it is working the voltage is 117v (This is the MPPT voltage of the Panels) - less than the 120v limit for ELV.

Also introduces the need for the panel frames to be earthed as well, - the stainless spiked washers for between the rack and the panel frame weren't supplied.

Cheers

[AlecK]

5033: 1.4.51 says the array voltage is the open circuit voltage of the array; 4.2 the same
That's what counts for determining whether the array is classed as ELV or LV.
Remembering that ESRs still currently cite 2012 edition, with no Amendments (though for this aspect that makes no difference).

Panel Voc 47.8 x 3 = 143.4 V this array is definitely above 120 V and is LV;
even leaving temp factor out (to avoid guessing the min temp) which can only increase the value).
Making the installation of the panel high risk PEW requiring inspection

And, as you've noted, requiring earth fault alarm [3.4.3] and earthing of the module frames [4.4.2.1]

[1Sparky]

Further to this, I recall reading somewhere in the 5033 standard that the max input voltage of the pce cannot be exceeded - the max voltage of the solar inverter is 145v, with the temp. compensation this is over. - I'm having trouble locating the clause for that, any idea where I can find it?

Cheers

[PeteRig]

Try AS/NZS 5033:2012 clause 4.3.1 (b) could be what you are looking for?

[1Sparky]

So I emailed this off to the supplier last night:

Hey David,

The system voltage is determined according to AS/NZS 5033:2014 A1+A2 by the clauses 1.4.51 and 4.2,

image.png
So 143.4+(-0.29/100(3-25)(3)

PV array maximum voltage = 143.59V

Well above 120v to be included in ELV and is therefore LV and requires earthfault detection/monitoring of the panels, with remote alarm notification, also PV frames require earthing with the spiked stainless washers - Clauses 3.4.3, 4.4.2.1 + 4.4.2.2(b).

Figure 4.5 also uses PV Max V to determine if it is classed as ELV or LV.

4.3.7 Plugs, sockets and connectors - (k) only be mated with those of the same type from the same type from the same manufacturer. - (The MC4’s on the panels are different to the ones on the DC cables)

Cheers

Vaughan

And his reply this morning is:

Hi vaughan, those are interpreted to not apply,

David

I'm open for suggestions for my next reply, Thanks in advance

[AlecK]

Clearly they believe they can pass the system off as compliant - and they've already been paid for it.
So unlikely to be open to just a friendly approach.
Unless the customer is paying for your time to try to get the error corrected; you're wasting your efforts.
So maybe time to talk to your customer, before deciding how much you want the job.
They are in a position to demand a refund.

May also be time to contact ES, as if you walk away some cowboy will come along and just hook it all up.
And if they believe the supplier's BS about it being ELV; they won't bother having it inspected.

[1Sparky]

Who are you meaning as ES?

Thanks again

Vaughan

[AlecK]

Energy Safety (division of Worksafe)