PV System Limits

[Mark.W]

Thanks for your prompt comments, much appreciated. I take your point about mixing portrait and landscape panel mounting, but looks are not that important to me (they are to my wife though!) - what bothers me is that if I'm shelling out such a massive sum to have an array installed I want to be damn sure that I am maximising the benefit of doing so! Due south is to the side of my house, so there isn't really the opportunity to see them at a distance to appreciate the true ugliness of a mixed orientation of panels...

On the gap to the edge side of things, my roof is slate - which I understand is not a favourite of PV installers! But that does mean that nothing's cemented in, other than the ridge tiles. I am happy to accept the wind loading argument, but I'd like to know whether it's 2 or 300mm...

Some installers say 200mm and some say 300mm, I suppose it depends on who they studies with. I was personally told that 200mm from top to allow for wind loading and 200 mm from bottom because if it rains you want the water to drip into your gutter, not over the side of your roof.

We may all have different views.

Mark

 

[Mark.W]

First install done in October 2009, pushing on 60+ installs at the moment. You?

 

[mmccx]

i did 31 or so at my old company, but mainly electrical side of things but was involved on the roof. Then said company went to do consultancy so made me redundant as well as the other fitter. For the last 3 months i have been working for a supply company designing and specking systems for installers. Now i have just got a new job as an electrical engineer focusing on the electrical install so im going back to installing which is what i love

Lots of installs for you though!

 

[Mark.W]

On the gap to the edge side of things, my roof is slate - which I understand is not a favourite of PV installers! But that does mean that nothing's cemented in, other than the ridge tiles.

I have found that slate tiles are one of the easiest to work! There's a good method to it!

Mark

 

[Mark.W]

i did 31 or so at my old company, but mainly electrical side of things but was involved on the roof. Then said company went to do consultancy so made me redundant as well as the other fitter. For the last 3 months i have been working for a supply company designing and specking systems for installers. Now i have just got a new job as an electrical engineer focusing on the electrical install so im going back to installing which is what i love

Good man!

I've got my first farm install starting in April 23.6kW, gonna be interesting. Got a couple of others in the pipeline that could possibly come in including a 100kW install.

 

[mantissa]

Some installers say 200mm and some say 300mm, I suppose it depends on who they studies with. I was personally told that 200mm from top to allow for wind loading and 200 mm from bottom because if it rains you want the water to drip into your gutter, not over the side of your roof.

We may all have different views.

Mark

Well there's no problem with the top and bottom edge clearance, but what's your view on clearance to the edges then? With the Sanyo 11P+6L arrangement, it should be possible to have approx 700mm (350 per side), so long as panels can be butted up against each other with no gap. Otherwise there's not much slack in that 700mm figure to provide a gap between the 6L panels and still have 600mm left over. Might work I guess, 6 panels, 5 gaps, 20mm per gap?

 

[Mark.W]

Well there's no problem with the top and bottom edge clearance, but what's your view on clearance to the edges then? With the Sanyo 11P+6L arrangement, it should be possible to have approx 700mm (350 per side), so long as panels can be butted up against each other with no gap. Otherwise there's not much slack in that 700mm figure to provide a gap between the 6L panels and still have 600mm left over. Might work I guess, 6 panels, 5 gaps, 20mm per gap?

With the dimensions you stated ie 1580mm x 789mm, your portrait panels would come to a total of 8.93m including all clips based on 11 panels and 9.74m based on 12 panels. The 6 panels in Landscape would come to a total of 9.62m including all gaps.

The Panels is Landscape do not need to have any gaps in between them, as the bars will be mounted vertically. I would personally still keep the gaps the same as the portrait panels.

You will have plenty of gap around all edges of your panels with this configuration.

Mark

 

[dansk]

200mm - for permitted development

 

[mmccx]

thats above the roof,

we are talking about borders which is debatable

 

[dansk]

thats above the roof,

we are talking about borders which is debatable

Agreed - but good info here http://www.electriciansforums.net/p...s-green-energy-forum/27150-building-regs.html

 

[mantissa]

Agreed - but good info here http://www.electriciansforums.net/p...s-green-energy-forum/27150-building-regs.html

That's good stuff - although the 200mm from the ridge requirement is often confused as covering the distance to the roof edge - which it doesn't. I like the 3 times the height off the plane of the roof suggestion which is in that thread - there seems to be real reason for it (wind loading). Also linked from that thread is the amazing story from Dorset which seems to make a nonsense of wanting to do it right. I went to my local planning office today for an informal consultation and all they were able to stipulate was the less than 200mm off the plane of the roof and down from the ridge.

 

[dansk]

Quality is that link, i cant believe my eyes when i see that photo - we should have a sticky on here named "Bodgerwatch" like we have in the NAPIT magazine, of all the dodgy installation work.