How to plan for mounting

[Prefersdirt]

This has to exist ... a simple, how-to or walk through manual on mounting panels. I need to mount panels on the roof and looking through things I am (again) feeling overwhelmed.

Thanks

 

[Hedges]

In order of importance (or sequence of possible events?):

1) Don't fall off roof.
2) Don't make a leak in the roof.
3) Don't burn down the house.

Depending on type of shingle or other roofing materials, there are various standoffs and flashing.
Typically some bracket gets lag screwed in place with some sort of goop or flashing to spill water.
Then rails are bolted to a row of brackets.
Then top-clamps are used to hold panels on rails.

Look up commercially available mounting systems for your type of roof; from there you can buy or DIY.
I have used Unirac rails, another time U-channel from the hardware store.

 

[opticalcarrier]

this DIY guy on YT had a great series of 4 videos going over it here:

Im curious as to if you are building a new house, are there any other options or different ways to make it all more seamless? like putting in the flashing footers in first before the shingle tabs? just curious?

 

[Hedges]

Im curious as to if you are building a new house, are there any other options or different ways to make it all more seamless? like putting in the flashing footers in first before the shingle tabs? just curious?

Or when re-roofing.
I think that could be done with standoffs and flashing installed as shingles go in.
I got some solid standoffs that were 6" or so tall. No way to install and flash on existing shake roof. 2-piece standoffs with low profile base would be possible.
By marking where rafters are, hardware could be lag screwed into those rather than just the sheathing.
You would have to determine approximate size of panels at that point in construction - rooftop is usually done with top-clamp of panels so location of rails doesn't need to be exact, but rail spacing is two per panel.
Often, roof is done about 18 months before completion of a custom home. You could complete the PV array at that point, maybe get the system operating early.

 

[opticalcarrier]

man apparenty im such a n00b, i didnt understand anything of you just said ?

 

[Hedges]

Sorry!
It can be done. I would try to if re-roofing. I do everything myself.

You want your roof completely water tight. Might not be a good idea to let a gorilla with a drill and a caulk gun do the work after roof is finished.
If you can get a roofing company to put in the roof together with rails to hold solar panels, that would be best because they would flash it properly to keep water out.

Panels come and go on the market, and are all sorts of sizes. The mounting rail locations are determined to fit the panels.
You might want to have the panels on-hand before having the mounts installed.
Make sure the design will comply with building codes. There are requirements regarding where on the roof and how many attachment points.

 

[opticalcarrier]

ah right- im going to have the roofers do the flash footings and rails. I'll prob have to do the panels myself though, but will see. AltE is putting the package together for me so it will match up. I talked to the local building inspector and fire marshall on the roof locations also.

really was just asking if it'd be a better idea to put the flashings down first, then shingles. but that may keep the shingles from going on correctly, and may make it all slower?

 

[Hedges]

I would think (for some types of hardware) standoffs first, then shingles and flashing installed in layers.
If the standoffs were placed and flashing left on them, roofer should be able to position shingles and flashing properly.

 

[Prefersdirt]

Unfortunately, our roof is complete. And fortunately, is in great condition. So going to have to figure out a way to mount with it as is. Interesting idea to talk with a roofing company. Due to HOA issues, I can't do ground mount. Will watch the DIY video and reach out to the company that did the roof on our last house.

I really don't want to be on the roof. Steeper than I thought (I went up to measure the areas for panels).

 

[ArthurEld]

I think the Iron Ridge Flash Foot 2 are pretty good. They might not be fool proof but I think a gorilla could do it.

 

[opticalcarrier]

Unfortunately, our roof is complete. And fortunately, is in great condition. So going to have to figure out a way to mount with it as is. Interesting idea to talk with a roofing company. Due to HOA issues, I can't do ground mount. Will watch the DIY video and reach out to the company that did the roof on our last house.

I really don't want to be on the roof. Steeper than I thought (I went up to measure the areas for panels).

You can say that again - mine is 45deg. I think if the roofers can get me to the point where the rails are square though, Ill be able to use them to keep me from breaking my neck, can can do the panels myself

 

[Prefersdirt]

I think the Iron Ridge Flash Foot 2 are pretty good. They might not be fool proof but I think a gorilla could do it.

Finally got the guy helping me to come out and look at the roof. I am going to use the Flashfoot 2 mounts. This is going to get interesting. If I was going to do a much larger project, I think I would want to pay someone to do this. Especially on the barns I envision covering in panels.

 

[Voltaire]

Hello.
I'm in Southern California and headed for a re-roof of my home. I'd like to have the roofers install flashed brackets for solar which, at some point, I'll DIY (probably buying some of those cheap used panels I see listed on Craigslist).
Which brackets should I ask the roofer to use, and how far should they be spaced apart to give myself the best flexibility in the future when it comes time to attach rails and panels?
Also, I'd like to run the wires to the panel inside my attic, rather than on the surface of the roof. What sort of properly-flashed electrical box should be installed at the time of roofing in order to make that happen?
As this thread indicates, it's way better to do penetrations at the time of re-roofing than it is to do them after the fact. I'm planning to use three-tab composite shingles, if that helps.

 

[zanydroid]

I don’t actually understand this whole thread for three tab shingles after having done a reroof last year and DIY install for the first time this summer. Maybe for other roofing materials front loading the work is a good idea.

For a reroof I buy that moving plumbing ducts and HVAC vents at the time of roofing makes a ton of sense. Those would be painful to patch and are also pretty big.

Bias disclaimer: I have easy attic access to below the rafters to visually verify that rack anchors went in with correct alignment and no bursting

Below blindly installing brackets means just putting them up there with only a draft plan of where the panels will go. At least have a layout done with some roughly representative panels, understand different panel geometries, and understand setbacks from the roof ridge and other places.

I would say ironridge is probably a better rail for blindly installing brackets as you suggest, since it has longer cantilever to compensate for being imprecise with rail placement.

The main advantage I can think of for doing it at roofing time is that it is slightly easier to find rafters if the roofer marks them as the roof is built up. But you can also find rafters using feeler holes and then use standard size foot flashing to cover it. You have a foot of horizontal spacing with the flashing to cover up your feelers. If you are using compact foot flashing then you have to be much more precise with feelers, so maybe this is something good to delegate to a contractor with more experience.

Maybe you can avoid pulling nails that pulling flashing after the fact would require.

A big disadvantage of blindly installing brackets without knowing panels nor layout is that it increases the likelihood you will not mount the panel clamps on the approved area.

Another disadvantage is whether the roofer knows the rack hardware.

There are videos with all of the different flashes roof junction boxes in one. Some use big flashings which is good for wiggle room but bad for cutting shingles and pulling nails.

 

[Voltaire]

I don’t actually understand this whole thread for three tab shingles after having done a reroof last year and DIY install for the first time this summer. Maybe for other roofing materials front loading the work is a good idea.

For a reroof I buy that moving plumbing ducts and HVAC vents at the time of roofing makes a ton of sense. Those would be painful to patch and are also pretty big.

Bias disclaimer: I have easy attic access to below the rafters to visually verify that rack anchors went in with correct alignment and no bursting

Below blindly installing brackets means just putting them up there with only a draft plan of where the panels will go. At least have a layout done with some roughly representative panels, understand different panel geometries, and understand setbacks from the roof ridge and other places.

I would say ironridge is probably a better rail for blindly installing brackets as you suggest, since it has longer cantilever to compensate for being imprecise with rail placement.

The main advantage I can think of for doing it at roofing time is that it is slightly easier to find rafters if the roofer marks them as the roof is built up. But you can also find rafters using feeler holes and then use standard size foot flashing to cover it. You have a foot of horizontal spacing with the flashing to cover up your feelers. If you are using compact foot flashing then you have to be much more precise with feelers, so maybe this is something good to delegate to a contractor with more experience.

Maybe you can avoid pulling nails that pulling flashing after the fact would require.

A big disadvantage of blindly installing brackets without knowing panels nor layout is that it increases the likelihood you will not mount the panel clamps on the approved area.

Another disadvantage is whether the roofer knows the rack hardware.

There are videos with all of the different flashes roof junction boxes in one. Some use big flashings which is good for wiggle room but bad for cutting shingles and pulling nails.

Thank you for your excellent response. I see here that panel length ranges from something like five to six feet. So, if I was planning for, say, 20 panels laid out in two long rows of 10, would it make sense to tell a roofer to install three rows of mounts spaced, say, slightly less than five feet apart figuring that six-foot panels would just overhang the ends more than five-footers would? That's assuming that the two rows would share a central support? Or maybe it would be better to spec four rows of mounts, two rows for each row of panels, spaced at just under five feet per row and a foot or two between banks? Or, it looks like panel width may be more consistent than length, so maybe it's better to plan for horizontal rather than vertical orientation? I've got a broad, relatively-uninterrupted space to work with if I move a vent and a stove stack.
I'm happy to go up in the attic and check for burst. I'll spec these mounts high enough that I'll have easy access.

 

[zanydroid]

Generally speaking panels are about 40-46" wide and it is more efficient to mount on portrait rather than landscape.

Very good idea to move those big ass vent and stove stacks to a better place. Any shadow is a massive killer on solar panel production. Maybe you can get rid of some gas fired appliances and delete a vent.

Not sure what you mean by two rows sharing a central support. That doesn't really work except maybe for a rail that's aligned parallel to panel edge so that you can land two rows exactly in the middle, which isn't a common thing and i'm not even sure it's supported by the racking system. Usually you have 2 rails per panel, about 1/5 and 4/5 along.

Look in the manual for the solar panels to see the clamping range in landscape and portrait. Note if you change form factors for longer vs shorter ones you're very likely to go past this point on one of the two rails.

Can you take a picture or do a drawing of your roof? That would help. I prefer high resolution to google aerial photos (unless the latter is non-blurry).

 

[zanydroid]

OK so I'm not a hypocrite about visual aids, here are screenshots from my project notes

Mounting specs for panels



Rail vs footing vs panel positions. Round dots are footings. The solid grey lines are rails. The dashed gray lines are the purported rafter locations.

The rectangular grey boxes with pink lines going between them are rooftop junction boxes. Yes there's too many of them, I'm going to get bit in the butt by roof leak karma.

 

[zanydroid]

Or, it looks like panel width may be more consistent than length

In terms of geometry.

For a long time they had a pretty consistent 40”ish width, and extra cells were added to the long dimension.

However that is subject to change with new production lines. For instance with a current popular cell geometry the solar panels end up wider and shorter.

If you are buying panels off Craigslist you can probably figure out what the common width was for the era of panels you are buying.

The idea of planning for landscape mount is interesting, you would have higher racking costs and more roof penetrations. You also need to look at a couple different panels to see if the landscape mounting points are in the same area.

Another thing you could do maybe is have them mount one row and set of feet so you know where the rafters are and then you add more yourself based on the panels you end up with ?‍

But you probably still need feelers because the rafters are not guaranteed to be as straight as you might think.

 

[Voltaire]

Wow. Great suggestions. After I've seen what they've done to the net metering rates in California, I'm less gung ho on this. But it's definitely still a must-do in terms of having some mounting points installed during re-roofing. looks like two sets of rails per line of panels is what I should go for and moving stacks. I just bought a new gas-fired water heater last year, so I think I'm stuck with that chimney for a while. But, an electric heater might be something to consider. We only use the gas fired one for a month or two per year.

 

[zanydroid]

Under NEM3 you can still cancel out your power bills for 9 months out of the year if you buy a battery (I mean without overpaneling like crazy for winter). Especially those insane summer peak rates if you live in a place with those $0.60/kWh prices and need AC.