Plumbing Vents and Solar Installations

[gkz]

We're considering adding solar to our roof, and there are several plumbing drain vents where we'd like to place solar panels. One reputable solar installer suggests avoiding these, therefore missing out on the full number of panels our roof could support. Another reputable solar installer says it's fine to cut the pipes short, to about 3", and as long as we leave a 3" clearance over the pipe, it should still work fine. I've spoken with the city code expert at our local city hall, and he said he'd be willing for us to cut the pipes shorter than the code required 6" height if we received information from plumbers suggesting that the pipes would still function just fine at the shorter length. It is the city code expert's guess that the 6" requirement is just to keep snow from plugging the plumbing vents, and since the panels will do a fine job of keeping the snow off the vents, a shorter pipe should be permissible. He wanted me to check, however, with plumbing experts to ensure his hunch is correct. Is there any reason that cutting such a plumbing vent to just 3", then giving about 3" of additional clearance between the top of the vent and the solar panels, would not work well? How long do you think the plumbing vent needs to be to function optimally? How much clearance should we ensure exists between plumbing vent and solar panel?

Thank you so much for your advice!

 

[hj]

The distance between the vent and the solar panel is not a consideration, but I doubt that the solar panels will prevent snow buildup. The panels will be on an angle, so just cut the vents down, then install fittings to offset them around the panel.