PV Quotes invited, 4kw Watford, Herts (1 mile off Junction 19, M25)

[saint]

A recent hookstop installation : https://picasaweb.google.com/113260...&authkey=Gv1sRgCPOJk_LUsZ7-Tw&feat=directlink

Roof and working edge protection will still be needed, so some scaffolding will be needed.

We've done nearly 100kW each of solar limpets and Hookstops, - prefer hookstops.

The last image in that link above is a 20kW solar limpet

We find we still occasionally end up with broken tiles under a limpet, not had one yet under a hookstop.

Worcester - have to say those anchors fit those tiles really well. What make are they?

 

[Worcester]

@saint Redtip, same as the hookstop, Andy @ Sibert can get them for you Redtip Hookstop plus Redtip M100 for plain tiles
Final picture was Solar Limpets

Neither of those two are the cheapest option, I know I over engineer roof fixings, however in my book it's got to last 40 odd years . On a 4kW system that typically means about 50-60 roof hooks (depending upon layout and wind loadings), so it adds about £250 -£300 to the cost over a universal roofhook - Is it worth it? We won't install any other way.

@FB lol.

 

[saint]

Thanks Worcester. doesn't seem to be any adjustment in the anchor where as the limpet allows you to string off the rail for a nice and flat array.

50-60 anchors on a 4kW? OMFG!

@saint Redtip, same as the hookstop, Andy @ Sibert can get them for you Redtip Hookstop plus Redtip M100 for plain tiles
Final picture was Solar Limpets

Neither of those two are the cheapest option, I know I over engineer roof fixings, however in my book it's got to last 40 odd years . On a 4kW system that typically means about 50-60 roof hooks (depending upon layout and wind loadings), so it adds about £250 -£300 to the cost over a universal roofhook - Is it worth it? We won't install any other way.

@FB lol.

 

[Worcester]

In the simplest possible install, 4 rails, 8.2 m long @ 900 spacing closed up to 450 at each end to cope with -ve edge pressure from wind loading = 11 hooks rails per rail = 44 hooks, can't do it with less than that and ensure that the load is evenly spread across all the rafters. Now end up splitting over two roof areas, and you soon add in another dozen hooks.

 

[Gavin A]

looks like overkill to me on most roofs tbh.

Our SE reckons most traditional roofs with perlins and 50 x 75mm rafters, the point of concern is the perlin's ability to take the entire extra loading of the array, rather than the capacity of any of the individual rafters (so we've strengthened a fair few perlins).

Which makes a lot of sense if you consider that modern trussed roofs often only have a 35 x 70mm rafter every 600mm vs a 50 x 75mm rafter every 400mm or so for the traditional roofs, so there obviously must be a fair degree of additional loading capacity on the 50mm rafters.

So we work to the schuco mounting kit spacings, but use 80mm bolts as opposed to the 60mm bolts BRE tested, so we should have a 1/3 higher pull out value. Essentially that works out at 800-1200mm spacings, with the brackets zig zagged up the roof, so that 2 out of every 3 rafters minimum are mounted to on each span.

On 35/38mm trussed roofs we mount to every second rafter, but double the rafters up as our SE reckon's they're generally not up to it even if you were to mount to every rafter as they're built to much tighter tolerances already.