Solar panels on flat roof

Nickmpower

Well-known member
Oct 31, 2014
146
Bay Area, California
#1
I am closing on a house that is partial flat roof and partial "low slope"

I am planning on installing panels on the flat part, and building racks to support them at the desired angle. Or possibly making them adjustable from 45 to 25 degrees since that wouldn't really require any more material. All the sunny days we've had during the winter the past few years is a motivator for that.

Does anyone have experience mounting these on a flat roof? There is a much greater chance for leaks on a flat roof and obviously that is something I am trying to avoid. I was thinking of just setting the racks on the roof and using some cinder blocks to weigh them down, anyone else have experience with this?
 

pooladdict

TFP Guide
In The Industry
May 14, 2007
819
New Brunswick Canada
#2
I would recommend doing a mounting system similar to what you said, if one end was able to move the panels to different angles you would be able to take advantage of the differing angles of the sun throughout the year. If mounted properly you shouldn't have much concern with them causing leaking, use proper caulk and lag bolts. I am sure some of the solar companies have mounting systems that can minimize leaks occurring and also be strong enough to withstand high winds.

If you are just thinking seasonally, you could possibly look at a weighting system, I would just be shy of using cinder blocks, if one moved, you would now have a roof sprinkler system.;)
 

DaneCE

Well-known member
Jul 1, 2011
342
VA
#3
What is the material on the flat roof? (asphalt, EPDM, PVC, etc)

I recommend trying to use weight instead of penetrating the roofing. Punching a bunch of holes is asking for trouble down the road.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
#4
You might want to take a look at h2otsun.com they have some interesting information about flat roof installations, this is of course slanted towards their products, but still handy to have.
 

Nickmpower

Well-known member
Oct 31, 2014
146
Bay Area, California
#5
What is the material on the flat roof? (asphalt, EPDM, PVC, etc)

I recommend trying to use weight instead of penetrating the roofing. Punching a bunch of holes is asking for trouble down the road.
Right now its a mix of asphalt and tar and gravel but I will be installing a new PVC roof. Yeah the problem with calking or most anything similar it that it will deteriorate.

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You might want to take a look at h2otsun.com they have some interesting information about flat roof installations, this is of course slanted towards their products, but still handy to have.
Looks like they use the weighted method as well. The difference is their panels lay flat and mine will be at an up to 45 degree angle, much more affected by wind.
 

DaneCE

Well-known member
Jul 1, 2011
342
VA
#6
Would that PVC system happen to be Duro-Last? I install a fair amount of Duro-Last PVC, lately on several new 7-11 stores in my area.

If it was a Duro-Last system, you could easily anchor your framework using proper factory flashing details that would offer a permanent solution, lasting the life of the roof (15 to 20 years).
 

Nickmpower

Well-known member
Oct 31, 2014
146
Bay Area, California
#7
I'm going with IB roof. Im sure they probably have factory options as well. It would have to be done after the fact though as the house NEEDS a new roof and I wont be Installing the solar till February or march
 

DaneCE

Well-known member
Jul 1, 2011
342
VA
#8
I'm going with IB roof. Im sure they probably have factory options as well. It would have to be done after the fact though as the house NEEDS a new roof and I wont be Installing the solar till February or march
OK, that should be no problem. You chose a great type of roofing.