NE facing, 9 degree pitch? No problem sir!

[JulianC]

Went to look at this yesterday - single storey extension with a huge roof area. Only snag was it faced NE. Anything remotely S facing would have struggled to accomodate a kW due to dormers aplenty. So I ran some figures and it's coming out not too bad at all - only 2800kWh/hr or so, but the install is very easy so the customer is looking at an 8-9 year payback! Surprised me.

Anyhoo, it's a 'traditional' interlocking tile roof (incredibly well braced and with 1" ply sheeting overlaying the trusses, under the felt) but at a measley 9 degree pitch. Should I be worried about self-cleaning of the modules at this shallow an angle? Some module documentation specifies 10 degrees minimum, some doesn't specify an angle at all. I've always carried "minimum 10-15 degrees" around in my head, but it's never been an issue until now. Anyone know of any traditional hook/rail mounting systems that can increase the pitch be a few degrees? Thought I saw something once but can't remember where

Ta

 

[solarsavings]

You must be able to get a few(10 maybe) degrees using an adjustable hook between the highest and lowest points.

 

[JulianC]

The problem with tweaking hook heights is that unless the rails are rotated so that they are both aligned in the same plane as the panel lying across them, it is impossible to clamp them down as the clamp is going in on the **** relative to the panel. If you see what I mean. Don't ask me how I know this.......

 

[solarsavings]

If you were to put the modules in landscape and used once turned hooks your problems solved ( I think)

 

[JulianC]

Sorry, don't understand what you mean. I might just go with the 9 degree pitch and supply the customer a free hosepipe.

 

[solarsavings]

I was thinking of these Schletter - Roof hook Rapid2+ 45V - Segen

 

[JulianC]

Oh, I see. Ta for that. Still leaves a problem with the angle of dangle. Further investigation necessary.

 

[edexlab]

We've done an 4 kw install late 2010 which was a few degrees north of east , when I went to install the inverter etc I got the compass out and commented on the orientation and suggested delaying the install and going for a ground mount as he had 9 acres of garden to play with , he said he'd not mentioned it to our surveyor and told him he was aware of the orientation and was happy with a roof install ,this was due to 3 firms saying a ground mount was out of the question?
Anyway this was the one install I thought would struggle to meet the expected sap Kwh per annum as there is also some temporary shading from large oak trees
However on the first anniversary it did hit the target but by a close margin of around 6 kwh ,so it could easily have gone either way
not bad really as this is a poor location for Pv in my view especially when you look at other south facing jobs which all seem to hit the figure around 2 months early on average, we had one last year which installed in February hit its annual generation with 160 days left
to run (needless to say this bloke's sold as many systems for us as the rep with his referrals)