Discuss Solar farm earthing in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

loplug

-
Reaction score
73
Been doing some work today on a solar farm , from the subs there are 95mm 4 core Alu cables running out to the arrays where there is a box that splits the feed between the 2 inverters. Now the cable that comes from the sub is connected to the neutral bar at the mccb panel and marked with blue sleving at the array end it is marked with green and yellows sleaving and connected to bothe the inverter earth and neutral connections. This to me is wrong but what is the correct set up for earthing a solar farm should the inverters be earthed locally from the frame and earth mat system ? Or some other PEN system?
 
struggling to work out what you're saying the situation is, but the pictures obviously look to be wrong. Needs stripping out and redoing sensibly.

Sounds a bit like someone's not understood about using the armours as the earth or maybe misunderstood about grounding the neutral on the DC side (not usually needed, but is sometimes mentioned in manufacturers instructions).
 
It does look odd. I'll have a go at identifying a few points, but I think I agree with Gavin that it needs stripping out and re-doing.

- Is that armoured cable coming in? With those colours (the fourth core being G/Y not blue) it might not be SWA but RV-K.

- If it is armoured then the armour must be earthed.

- If the fourth core is G/Y it cannot be used as a N, but could in principle be a PEN conductor if other rules are met.

- It appears to have a combined neutral and earth (ie PEN). Although 7671 534.4 allows this sometimes, basically you cannot do it in 'consumer' installations in UK. ESQC reg 8(4) says so. So rather than simply being against non-statutory regulations (7671), it is probably against the law and subject to a fine at level 5 (£5k I believe) on the standard scale.

- 7671 would allow a PEN conductor up to that box and for it then to be split into N and PE if a) it had not been previously split and re-combined in the installation, and b) you had 'authorisation'. But given ESQC Regs and assuming it is a grid connected consumer installation, I cannot see how you get authorisation in UK.

- Do the inverters require a neutral?

More investigation or detail required for certainty.
 
Is the armour used as the earth?
it'd appear not from the photos, actually hard to tell it it's even SWA, if not then that's a lot more problematic as there is no separate earth, it looks as if it's got a plastic gland entry so erm.

Looks to me as if someone's ordered and pulled through the wrong cable, then attempted to bodge it.
 
there is no armour on the cable the green and yellow core is conected to the neutral bar at the dist board end which has a link to the earth bar and yes the inverters do require a neutral
 
They appear to have set it up as a TNC system, with cores correctly marked for this under the current version of bs7671. But that part of the regulations only really exists just in case there happens to be an old TNC installation in existence which needs to be altered or repaired, so they have to make rules for it. I don't think it has been allowed in new installations since the 13th edition.
 
It needs another conductor to each point whatever you do, the regulations require a cpc connected to the earthing system in use at the source of the circuit to be present at every point on a circuit.
 
which reg is that i thought most dnos did not alow the export of pme and it is common place to have tt systems in out buildings fed from pme suplied distboards
 
Yes, but you still take the cpc to the final point of termination, usually in the form of the cable armour, but don't connect it at the load end. You set up the independant TT system at the load end of the supply.
 
yes but is the cpc not only there to earth the armour and if it was a double insulated cable unnecessary
 
I think that would be a departure from the regulations, but would obviously require design justification.

I should think solar installs are a bit different anyway as the inverter is the source of the supply, not the load!
 
Yes, but it is still a source of supply at those times, that is the whole point of the system!

As far as I know multiple sources running in synchronisation need to have a single common earthing system.
 
Looks as if the two smaller cables in that panel are SY cables ( those with the braided earth link between them) which is a no-no for external cabling before you start to worry about the earthing system....

Is there no ''Approved'' distribution/layout drawings available for this solar farm installation, at least then you'd know what the system design concept is or was, and if it has been altered by others??
 

Reply to Solar farm earthing in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock