Solar panels on a roof without a ridge
This article in Fine Homebuilding has a good summary of the rules for placing solar panels on a residential roof:
https://www.finehomebuilding.com/2020/05/05/rules-for-rooftop-solar
It has this quote from the ICC “International Solar Energy Provisions”: “At least two 36-in. or wider paths must be provided on separate roof planes from the lowest roof edge to the ridge.”
And: “Once at the ridge, the path must continue along its length to provide access to cut vents at any place along the ridge. The size of the path along the ridge depends on how much of the roof is covered in PV panels. For roofs where PV panels cover up to 33% of the total area in plan view (essentially, as seen from above), the panels must be at least 18 in. away from a horizontal ridge on both sides to create the 36-in.-wide path. Where panels cover more than 33% of the roof, a 36-in.-wide path is required on both sides of the ridge.”
Straightforward enough. But what happens if you have a flat roof, and only one plane? I’m working on a project where the roof is actually dish-shaped, with internal gutters. We’re trying to fit as much solar up there as we can. Do we have to leave 36″ on one side, two side, three sides, four sides?
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Replies
I'd extrapolate that to say you need a 36" path on three sides, but your AHJ will have the final say.
I'd second the "check with your AHJ" (and maybe your fire chief) vote, especially with an unusual roof. I can't find the exact code reference right now, but I seem to remember last time I looked into this that there was an exception if approved by the local fire department -- the point of the access paths is that firefighters sometimes want to access a roof to cut holes at the peak for smoke ventilation, but if your roof is not conducive to this, they may decide they don't need the access paths or specify where they would like to see access paths.