1st install advice

[Maff]

I have just set up a PV installation company and we are embarking on our first job and MCS accr. In order to maximise the yeild of the array for the given roof area we are going to install 15 modules in 3 parallel strings conected to an SMA SB-3000 TL inverter, the thing is on the 2399 course array frame earthing was a bit vague, my research says we will need a rod and RCD protection, does anybody have any advice on distances from property etc and will I have to go and buy an electrode tester?

 

[Graeme Harrold]

SMA TL will require a rod on TN-C-S, and why not use method 2 to check the suitability of the rod.....

 

[Maff]

what is min clearance that you can leave around the edges of an array

 

[Graeme Harrold]

Been discussed many times, however there dosent seem to be a specific regulation covering it. Most courses recomend a minimum 300mm clear zone from the roof edge. This seems to be the acceptable distance that reduces wind loading/lift implications

 

[Maff]

What about 300 up to the ridge, 600 at each side and 200 at the bottom, would that be pushing it?

 

[Graeme Harrold]

You need to get it right on your 1st install and keep it there. 200mm is pushing it IMHO

 

[BruceB]

The risk of 200m at the bottom is:
- wind catching the edge if it is in an exposed location
- rainwater running down the panel and overshooting the gutter

It is not a definite no-no, but I would be wary of going so close on your first install or until you have the experience to make a sound judgement of actual conditions on site. You would need to be able to explain to your assessor why you did it that way.

Regards
Bruce

 

[Worcester]

We being the cautious types like to go for 450mm if we can, we'll only squeeze down to 300 on very few occassions, and then we nearly always decrease the bracket spacing (doubling up effectively) in the bottom corners. All depends exactly what the wind uplift calcs come out at.

Don't forget you'll need to show your structural calcs etc for the MCS assesment.

 

[Maff]

cheers , all being taken on board.I am doing a CU change at the same timeand installing a split load board, as its a TL inverter can I put the 20A mcb on the protected side or does it have to be its own bespoke RCD on the unprotected side, prob more stupid questions to come, we have gone for the smaller array which has 600 clearance all round to be on the safe side at the expense of 0.6KW.