Gounding solar panel frame and negative.

[asdex]

Hi, I'm just looking at earthing now and see it mentioned about earthing the negative of the system. I have six panels that will be connected to a Classic then batteries, just a standard system at 24 volts. Where would I ground this setup? Are there any wiring diagrams about?
Thanks,

[vtmaps]

On the Classic the PV negative and the battery negative are connected to each other.  If you ground one, you ground the other. 

The Classic has built in GFP.  If you ground either your battery or PV negative, you will defeat the GFP.

--vtMaps

[zoneblue]

You have three choices:

1. Use the classic's GFI.
2. Bond negative to earth in the dc disconnect
3. Run an unbonded 'floating' setup.

Generally youd only do choice 3  for 12 v PWM systems , in RVs etc. Not recomended for higher PV voltages.
Choice 2 is the industry standard
Choice 1 is the now the law. It has some advantages, but some feel they also introduce additional issues. Search this forum for an entensive discussion on teh topic.

[asdex]

Hi, thanks for your reply. Now that I have an Outback inverter which looks to says to bond the negative from the battery to earth, I'll do that. (Choice 2). I'll look at taking a lead from the negative bar to and earth stake. I'll also have an earth stake our by the PV panels for the frame of the panels and one for the pole of the wind generator. I'll need to read the Outback instructions further to see if I bond the 230v neutral to earth as well.
Cheers,

[zoneblue]

Generally what you want is a single earth bus, with a single unjoined (or irreversibly joined) conductor connected from that bus to the stake. Avoid daisy chains. Tie all metal equipment casings to the bus.

[zoneblue]

Generally its best to tie all your earth stakes if you can. Some juridictions permit multiple stakes if the distance apart exceeds a certain amount, but there are some down sides. For the AC see http://midniteforum.com/index.php?topic=1775.msg17446#msg17446

[zoneblue]

Dont forget the SPDs, especially with the turbine in the picture.

[asdex]

The Outback installation says one earth for the DC negative and one for the AC neutral so I'll have to go with that. I'm not sure from the instructions yet if I earth the battery negative and all the metal casings together on one busbar but expect so. Therefore that would also mean the battery negative etc and the AC neutral connected together and earthed which seems odd.

[zoneblue]

The FX manual has a block diagram that shows three possible earthing configurations. Choose one. The diagram doesnt really go into the details though. Its assumed theres an electrician involved i guess, as their should be. Going the epanel route helps because theres a one less earth bus. If you use a DC disco and an AC load center you inevitably end up with two earth buses, three if you count the one out at the array. The point is to try to get all earths at the same potential. During surges any kind of resistance in the earth system will cause voltage differentials that can cause damage. I suggest you do lots more reading, and get a sparky to look over your plans and sign it off when you are done.

[dgd]

Asdex,
There is, apparently, a lot of useful information concerning safety and earthing outlined and detailed in NZ standard 5033:2014
Problem is the Standards Committee want you to pay several hundred $ to access this document, making it unlikely to be of use to individuals interested in PV RE systems.

dgd

[zoneblue]

Theres a good summary of NZ/AU solar related standards here:
http://www.seanz.org.nz/files/file/20/Standards+101+Version+1.1.pdf

The key ones are:

AS/NZS 5033:2014
Installation and safety requirements for photovoltaic (PV) arrays
http://shop.standards.co.nz/catalog/5033%3A2014%28AS|NZS%29/view

AS/NZS 4509.1:2009
Stand-alone power systems - Safety and installation
http://shop.standards.co.nz/catalog/4509.1%3A2009%28AS|NZS%29/view

AS/NZS 4509.2:2010
Stand-alone power systems - System design
http://shop.standards.co.nz/catalog/4509.2%3A2010%28AS|NZS%29/view

AS 4086.2:1997
Secondary batteries for use with stand-alone power systems
Part 2: Installation and maintenance
http://infostore.saiglobal.com/store/Details.aspx?ProductID=310289

And obviously AS/NZS 3000:2007 "Wiring Rules" overarch. I was told that its a legal requirement in NZ for PV installers (including homeowners) to abide by these standards, and they carry $10,000 fines. However its my understanding that if the array Voc is below 120V you can do the work yourself, however the 230V side has to be supervised by a registered electrician.

[asdex]

Hi, thanks for that info. My PV voltage will be under 120v and despite my obvious ignorance of things solar I am a reg electrician so will be fine with the 230v side. I downloaded a copy of the ASNZS5033-2014 so will have a read.
Cheers,

[zoneblue]

I had a quick look and the only ones i was able to find free online are:

https://law.resource.org/pub/nz/ibr/as-nzs.4509.2.2010.pdf
http://docs.niwa.co.nz/library/public/AS4086.2-1997.pdf

[dgd]

...
I was told that its a legal requirement in NZ for PV installers (including homeowners) to abide by these standards, and they carry $10,000 fines.

Don't think so otherwise there would be several million in fines due for collection.
Sounds like one of the ususal scam tactics to leverage $ out of home owners interested in RE.
Never heard of a PV installation inspector either.

However its my understanding that if the array Voc is below 120V you can do the work yourself, however the 230V side has to be supervised by a registered electrician.

...thought it was 50v mentioned in one of the standards?  I got the impression this was to make allowance for the RV/Motorhome people on 12v systems.

dgd

[zoneblue]

ELV is 50V RMS AC, 120V DC, ripple free. Thats defined in AS/NZ3000, which is eqiv to US NEC.