Panel Positions

[Sidecar Man]

Hi can anyone tell me if there is any rules on where panels can go. As in distance from ridge and edge of roof. Cheers

 

[sgt_woulds]

http://www.microgenerationcertification.org/images/PV Book ELECTRONIC.pdf

There are guidelines rather than rules - the important thing is to be able to prove your design will take the loads imposed by wind.

Anything less than 500mm puts you in the edge zones which requires more careful design.

In general you can be 300mm away from the roof edge without the design becoming ridiculous - this is dependent upon the roof and the situation. A hipped roof will experience more turbulence, and one next to the sea will require extra care...etc.

How tall is the building? A single storey garage in a sheltered location will be more tolerant than a 4 storey house by the sea.

2 other factors to consider are:

1) Lifting tiles to fit hooks can damage mortared ridges and verges. A rule of thumb is 300 at all edges for plain tiles, 300 at the gutter and 500 from edges and ridge for concrete Redland 49 type and large format modern interlock will possibly require 600 from the ridge. Not a problem for dry ridge and verge construction and slate roofs of course.

2) going too close to the gutter with a bolt-on system can lead to water overshooting the gutter and causing damp issues. 300mm min on a 45deg roof is a good rule of thumb.

 

[Sidecar Man]

That's great thanks for the information. It's a bungalow and fairly sheltered so should be okay.
Thanks for you help.

 

[sgt_woulds]

I should clarify regarding the lifting of tiles that the margins I suggest are for the edges of the panels to the margins of the roof. Assuming you are using panel base rails, your hooks can be upto 500mm from the edges of the panels (so 1m away from the roof edge for a concrete interlocking roof) with no chance of damaging the verge cloaking detail.

Bear in mind that if you are going into the roof edge zones you really want to keep the panel / hook overhangs to less than 300mm ideally. It depends on the rail / hooks you are using, the rafters details and expected windloads.

Another thing, when I worked at SC (back at the start of the century) we did some testing at BRE which suggested that with some rail / panel combinations oscillation could occur which would gradually loosen mortared ridge tiles.

Another reason to keep panel overhangs as short as possible...