PV array mounting hardware choices 12-12 asphalt shingle roof

[Jerry Liebler]

I must say this is pretty old school style hanger bolt, through a standoff tube, with a flashing and boot.

compare that to this system : https://www.youtube.com/watch?v=ohCCYqT1vgg

As before older isn't always inferior. I want 4" below the rails to clear roof ventilator caps and cool the panels.

[ButchDeal]

As before older isn't always inferior.

In this case older is inferior. They are relying on the sealant to last the life of the PV with no other physical barrier for the water.
Even the flashing with boot that they offer is not going to last as long.

I want 4" below the rails to clear roof ventilator caps and cool the panels.

putting PV modules over stack pipes is not up to plumbing code either. They should be relocated or left exposed.
If you are talking about attic vents then you can cover them and we have with ironridge just put the rails on either side.

4" below the RAILS? or below the PV modules?

The flashfoot 2 is 3.3" tall. Even the smallest rail, XR10 will add another 1" to that as the rail is 1.75" tall.
or you could use the XR100 rail (this was our pick) at 2.44" tall

[LPG]

As before older isn't always inferior. I want 4" below the rails to clear roof ventilator caps and cool the panels.

IPC P3103.1.3 does allow the pipes to be covered but they must be 2" above the roof, it also has rules for protection from wildlife and debris.
All that being said, It's a bad idea. I don't know where you are located, but most AHJs will see plumbing vents under a panel and will not pass your inspection, if you don't pass inspection your POCO may not let you interconnect so you'll have to build an off-grid only system. Then if your house burns down your insurance can latch on to the unapproved work as a reason to not pay out.

You're much better off using one of these:
https://solarbuildermag.com/products...ng-vent-pipes/
Hell, even an AAV will be better but some AHJs may complain about those as well and they also require that there be other vents in the home.

With all the code stuff out of the way, lets look at the chemistry side of things. One of the purposes of vents is to allow sewer and waste water gases to escape outside your home, if you put a panel above it all those gases are most likely going to cause issues on that panel, it could cause corrosion or even cause the adhesive to fail.

Lastly, the other type of vent is for exhaust fans, these just move moisture from indoors to outdoors. lets say it cold outside and warm inside, that combination will cause moisture to build up under your panel which could cause its own set of issue along with mold build up.

if you're trying to maximize the roof area just do it the right way and move the pipe or use a roof jack or ask your AHJ about AAVs. Don't cut corners because there's nothing worse than failing an inspection and having to undo your work, make the change then redo your work a second time.

[J.P.M.]

IPC P3103.1.3 does allow the pipes to be covered but they must be 2" above the roof, it also has rules for protection from wildlife and debris.
All that being said, It's a bad idea. I don't know where you are located, but most AHJs will see plumbing vents under a panel and will not pass your inspection, if you don't pass inspection your POCO may not let you interconnect so you'll have to build an off-grid only system. Then if your house burns down your insurance can latch on to the unapproved work as a reason to not pay out.

You're much better off using one of these:
https://solarbuildermag.com/products...ng-vent-pipes/
Hell, even an AAV will be better but some AHJs may complain about those as well and they also require that there be other vents in the home.

With all the code stuff out of the way, lets look at the chemistry side of things. One of the purposes of vents is to allow sewer and waste water gases to escape outside your home, if you put a panel above it all those gases are most likely going to cause issues on that panel, it could cause corrosion or even cause the adhesive to fail.

Lastly, the other type of vent is for exhaust fans, these just move moisture from indoors to outdoors. lets say it cold outside and warm inside, that combination will cause moisture to build up under your panel which could cause its own set of issue along with mold build up.

if you're trying to maximize the roof area just do it the right way and move the pipe or use a roof jack or ask your AHJ about AAVs. Don't cut corners because there's nothing worse than failing an inspection and having to undo your work, make the change then redo your work a second time.

The vent ought to be moved. Even if allowed by code, which in any reasonable code interpretation it won't be unless by not referencing the situation, which is not acceptance, it's a very poor idea. The vent will not have the same draw/draft it had prior to the panel placement meaning it won't do it's job as well as before a panel went over it, and the panel will get a lot of condensation on the backside that won't do it any good, not only from the moisture but also because of panel exposure to the godawful stuff in the vent effluent that will, in all likelihood, quickly void a warranty panel not to mention what it'll do to the panel and its performance and/or that of the string or array it may be wired to.

Putting a panel over a vent is simply a non thinking invitation to trouble. It's simply stupid.

[Jerry Liebler]

In this case older is inferior. They are relying on the sealant to last the life of the PV with no other physical barrier for the water.
Even the flashing with boot that they offer is not going to last as long.



putting PV modules over stack pipes is not up to plumbing code either. They should be relocated or left exposed.
If you are talking about attic vents then you can cover them and we have with ironridge just put the rails on either side.

4" below the RAILS? or below the PV modules?

The flashfoot 2 is 3.3" tall. Even the smallest rail, XR10 will add another 1" to that as the rail is 1.75" tall.
or you could use the XR100 rail (this was our pick) at 2.44" tall

The vents I'm planning to cover are NOT plumbing vents they are attic vents. What I'm looking for is more than 3 5/8" between the back of the PV module and the shingles.
I'm simply not going to use clamps IMHO they are truly old school and obsolete! That means I will not be using Iron Ridge rails. I am considering using the flashfoot 2 but to get adequate clearance I might have to add a layer of N S rails under the E W rails that hold the PV modules.

[LPG]

The vents I'm planning to cover are NOT plumbing vents they are attic vents. What I'm looking for is more than 3 5/8" between the back of the PV module and the shingles.
I'm simply not going to use clamps IMHO they are truly old school and obsolete! That means I will not be using Iron Ridge rails. I am considering using the flashfoot 2 but to get adequate clearance I might have to add a layer of N S rails under the E W rails that hold the PV modules.

Ok that makes a big difference then. Are these vents on the ridge of the roof? Because IFC has setback requirements to meet code compliance, I believe it's 3 feet from the ridge.

[ButchDeal]

The vents I'm planning to cover are NOT plumbing vents they are attic vents. What I'm looking for is more than 3 5/8" between the back of the PV module and the shingles.
I'm simply not going to use clamps IMHO they are truly old school and obsolete! That means I will not be using Iron Ridge rails. I am considering using the flashfoot 2 but to get adequate clearance I might have to add a layer of N S rails under the E W rails that hold the PV modules.

The pv modules sit on top of the racking which would be more quite a bit over 4", You seem to be forgetting about the rail height.
not sure why You are against the clamps they are very new design for irinridge

[Jerry Liebler]

The 3 1/2" standoff kit ($3.81 in black) from esolarwharehouse.com comes with a 1 1/2" dia sealing washer, possibly not an adequate flashing-waterproofing method. The same company offers a compatible "conventional" flashing for about $4, however one can buy just the 3" " microflashing" from Quickbolt for $2.44. The Quickbolt "pitch" about their waterproofing prowess seen here: https://www.youtube.com/watch?v=4NATgav4ZTE I find convincing. Replacing the 1 1/2" seal & washer of the SWH standoff with the 3" Quickbolt "microflashing" seems like the best alternative & should be as good or better than the all Quickbolt choice that doesn't elevate the rails enough for me. BOM cost $3,81+$2,44+$1.33 ( "L" foot & T bolt)=$7.58/ attachment is well under the Flashfoot2 solution which also isn't high enough.

[J.P.M.]

The vents I'm planning to cover are NOT plumbing vents they are attic vents. What I'm looking for is more than 3 5/8" between the back of the PV module and the shingles.
I'm simply not going to use clamps IMHO they are truly old school and obsolete! That means I will not be using Iron Ridge rails. I am considering using the flashfoot 2 but to get adequate clearance I might have to add a layer of N S rails under the E W rails that hold the PV modules.

Great. You'll still cut down on vent effectiveness, meaning the attic will get hotter in summer, probably adding to the A/C load, and damper in winter, increasing the possibility of condensation problems.

[Jerry Liebler]

Great. You'll still cut down on vent effectiveness, meaning the attic will get hotter in summer, probably adding to the A/C load, and damper in winter, increasing the possibility of condensation problems.

I think you are making a lot of assumptions that may prove to be wrong. All the electricity produced by the PV panels would, were they not there, be heat energy into the roof and the attic. Instead of the roof absorbing all of the solar energy, and heating up, most of it will result in electricity production or heating of the PV resulting in convection induced airflow between the panels and the roof. Any "dampness: in winter is a sign of another problem with the building, inadequate air sealing of the heated envelope. Despite a slight reduction of vent effectiveness I'd predict measurably LOWER attic temperatures during daylight throughout the year.

[Mike90250]

....... All the electricity produced by the PV panels would, were they not there, be heat energy into the roof and the attic. Instead of the roof absorbing all of the solar energy, and heating up, most of it will result in electricity production or heating of the PV resulting in convection induced airflow between the panels and the roof. .........

You can only expect about 20% of the solar energy to be converted to electricity and moved off the roof. The rest DOES turn into heat, but the air gap between the roof and panels allows a portion of that heat, to escape. Being in the attic after a install, does not "feel" to me, like it helps much, there are still exposed portions of the roof that get heated directly

[Ampster]

...... You'll still cut down on vent effectiveness, meaning the attic will get hotter in summer, probably adding to the A/C load, and damper in winter, increasing the possibility of condensation problems.

At the risk of starting a flame war over a post I made on another thread. Is there any benefit to the attic vents from the airflow between the roof and the panels? I am particularly thinking of a hot windless day. My layman's theory is based on the assumption that it is a 12/12 roof and that hot air rises. The OP does refer to convection induced airflow.

Another question for the benefit if the ignorant. Why would the attic become damper in winter? Are you referring to relative or absolute humidity?

[john phillips]

Did you tell us where you are?
Is this a grid-tied system?
Where I am things get really complicated if you go over 10kW nameplate DC.
If so what does your utility have to say about your system size?
I do not know about your building department but mine starts the permit with a letter authorizing a maximum size.
Do you need an engineer to sign your plans? If so IronRidge is a good friend to have because they will engineer your racking system.
What do you have agents clamps and what are you going to do instead? Is your alternative bless by an engineer or will you have to get one to sign for you?
Quick Mount PV is very tempting but as far as I can tell lacks the engineering required to get a permit.
I came here looking for information on Quick Mount PV. Does anyone have experience with them?
Good luck.

[Mike90250]

Something else you may wish to consider, is Ridge-line Venting, where there is a continuous vent along the roof ridge. It's small, but the length can add up. Not sure if it's a recommended idea in your area, but popular in mine

[J.P.M.]

I think you are making a lot of assumptions that may prove to be wrong. All the electricity produced by the PV panels would, were they not there, be heat energy into the roof and the attic. Instead of the roof absorbing all of the solar energy, and heating up, most of it will result in electricity production or heating of the PV resulting in convection induced airflow between the panels and the roof. Any "dampness: in winter is a sign of another problem with the building, inadequate air sealing of the heated envelope. Despite a slight reduction of vent effectiveness I'd predict measurably LOWER attic temperatures during daylight throughout the year.

As long as we're talking generalities and not specific applications, and without a lot more information, it's all assumptions. But based on experience and some of what I think I might know, I'll hang my hat on a reasonable probability of my assumptions having a higher probability of being closer to what might happen. Besides that's unimportant compared to what some AHJ or building code may direct.