Solar PV earthing advice

[Jimmyruk11]

Hi everyone - newly qualified on the solar pv side so be gentle please!
Builder has put 4 panels on roof and there is a velux window nearby. The panels are integrated in the roof and are class 2.
Am I required to earth? And if so what is the chance I will be able to earth then from in the loft?
Many thanks

 

[Geoff1946]

My solar knowledge is limited but to me a class 2 item doesn't need, and won't have provision for earth connection.

 

[binky]

in short no! Those integrated roof mounting systems are basically plastic trays, so not conductive like on roof metal rails. Some installers argue that earthing the metal frames is a good idea, more for testing the arrays for faults, but if a fault occurred, then you could potentially have a constant high DC voltage on the earthing, which I'm not convinced is safe and could do some interesting things to modern electronic devices which 'leak' a little to earth for smoothing AC voltages.

 

[Steviesparkie]

in short no! Those integrated roof mounting systems are basically plastic trays, so not conductive like on roof metal rails. Some installers argue that earthing the metal frames is a good idea, more for testing the arrays for faults, but if a fault occurred, then you could potentially have a constant high DC voltage on the earthing, which I'm not convinced is safe and could do some interesting things to modern electronic devices which 'leak' a little to earth for smoothing AC voltages.

That is an issue for the pv installer not the homeowner but i agree shiuld not need earthed on the face of it..

 

[stuboy]

My view is, that if you have lightning and a nice earthed array, mr lighning bolt will go, oooh look a nice path to earth lets give it max amps, and you could end up with a smouldering mess!

 

[binky]

That is an issue for the pv installer not the homeowner but i agree shiuld not need earthed on the face of it..

I think some of the PV installers run an earth to the frame but leave it unconnected by the inverter. In my own opinion, you shouldn't need it if you are careful about installing the MC4s and cable tie connections up off the roof, rather than leaving them flapping around in the breeze. The only other time I would install an earth bond is to sheet metal roofs, I discovered when I replaced my garage roof with box section profile, on which my own array is mounted, the array can induce a disconncerting voltage in the roof itself - not dangerous, but unpleasant when you touch the roof an earth it through yourself..

 

[Steviesparkie]

I think some of the PV installers run an earth to the frame but leave it unconnected by the inverter. In my own opinion, you shouldn't need it if you are careful about installing the MC4s and cable tie connections up off the roof, rather than leaving them flapping around in the breeze. The only other time I would install an earth bond is to sheet metal roofs, I discovered when I replaced my garage roof with box section profile, on which my own array is mounted, the array can induce a disconncerting voltage in the roof itself - not dangerous, but unpleasant when you touch the roof an earth it through yourself..

The pv i staller should do an IR test between frane and MET if a ove 2200kohms then not conductivr and no earth req...

 

[binky]

The pv i staller should do an IR test between frane and MET if a ove 2200kohms then not conductivr and no earth req...

I've not done much fault finding on solar, as my installs have not had issues - put it in carefully and you avoid all that nonsense. What I have noticed on sorting out other peoples work is that anything down at those sorts of IR levels tends to fail in wet weather, but that may be just because I've been called out for arrays with faults that only show in wet weather...

 

[stuboy]

Its always the hidden MC4 connector shuved in with no due care and attention that causes the trouble, even a quick tie wrap to keep them a little sheltered is very effective. If you read suppliers paperwork carefully, manufacturers say they only guarantee interconnecting MC4's of the SAME MANUFACTURER! If you compare a few different MC4's you can see some are slightly different, just enough to cause a little water ingress and cause nu-sense tripping :-(

 

[binky]

Its always the hidden MC4 connector shuved in with no due care and attention that causes the trouble, even a quick tie wrap to keep them a little sheltered is very effective. If you read suppliers paperwork carefully, manufacturers say they only guarantee interconnecting MC4's of the SAME MANUFACTURER! If you compare a few different MC4's you can see some are slightly different, just enough to cause a little water ingress and cause nu-sense tripping :-(

A lot of installers don't seem to posses MC4 spanners either


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