How close to the edge of the roof can panels be?

[cdherman]

Wow, you fellas give a hearty welcome of the most useful kind! Thanks for the excellent responses thus far.

All the fastening points of the racks will be directly to the supporting trusses. Morton pole buildings are a truss and perlon sustem. 45 feet divided into 9' bays with poles going down every 9'. There are large (2x trusses every 9' and then 2x4 cross pieces (perlons) that hold the metal roofing which runs peak to eve. There is no sheathing..

I am encouraged that there are no general "RULES" that say you cannot come closer than so and so close to the edges.

I would certainly have never thought of fastening to the rim or "flying rafter" of the building. That would be a definite recipe for disaster, at least based on common sense. When I re-roof a structure, I get nervous just working out there over an unsupported rafter (and not because I am afraid of hieghts).

I had not thought of the need for access to service the system. Am I going to have to dissassemble the array often? What's my chances? It will be VERY well grounded and pretty much zero debris. Is this a reason to buy one brand of panels over another?

The roof is 26.6 degree. Not quite latitude here (39) but steep enough to make walk around on it tricky. I was hopeing to not go up there for a good long while after I get it all done......

Well, again, thanks for the great advice so far.....

[Cariboocoot]

Most panel servicing consists of keeping them clean, whether of dirt or snow, and in some instances adjusting the angle periodically to stay relatively parallel with the sun: http://www.macslab.com/optsolar.html

My roof here is 37.5 and I go up there twice a year. Haven't fallen off yet!

[mike95490]

22 sharp panels, in a pure grid-tie system, 1 bad panel after 6 months, spotted visually and replaced. Had walk isles around panels, to wash them on a 2nd story roof.

If you can get to the opposite pitch and wash them from the ridge, that would work.

[icarus]

As a follow up to a previous picture.

This is a picture of the entire slab of snow oozing off a standing seam steel roof. Bitter cold, building heat melting a small amount of snow on top of the snow, causing it to refreeze into the classic ice dam. This particular building has the entire winters worth of snow on the roof. The building was un-heated until sometime in March. There is often enough strength in the ice to hold the entire snow "bridge" ooze all the way to the ground, leaving a tunnel!

Often the entire slab will slide, with dangerous mass when it lands, but once again, snow and ice is pretty powerful (and cool) stuff! Because the entire mass can slide as one, it can under the right circumstances take all kinds of stuff with it, solar panels, stove pipes, antenna mounts etc.

Tony

PS This wasn't taken yesterday,, a few days ago! LOL