Things to do while re-roofing in preparation for solar module installation?

[Chris D]

Hi, and thanks in advance for your advice and direction. Brand new to the forum, and I searched the forum and couldn't find this subject addressed specifically. If it has been, Please post a link to the thread.

We live in a simple ranch house with a three in twelve hip roof. While still serviceable, the shingles on the roof definitely don't have the 25 years in them to match the warranty on all of the solar modules, micro inverters, and racks that we plan to install. They might have five years in them, so we're hiring a contractor to do a complete tear-off and replace them with quality shingles before we purchase our panels and install them.

Is there anything special we should do, or ask the roofer to do, so we won't have any forehead-smacking moments while installing the solar equipment after the roof is renewed?

I've done enough homework to know that while it would be foolish to re-roof the house myself, we can save substantial money by doing the bulk of the panel installation stuff ourselves with some adult supervision from an electrician who we would contract with to actually do the tie-in. Planning to buy a complete kit from anapode, or a similar company. Like this. If people have experiences with these folks to relate, or advice on other suppliers of DIY kits, I'd love to hear that too. We're not married to any particular supplier.

Anyway, thanks again,


Chris

[peakbagger]

My prep under the new shingles was to install Grace Ice and Water roof membrane after I had stripped the roof. I installed it from bottom to top. It seals nail holes and is easy to patch into as it sticks to itself rather tenaciously. Its pretty much standard in commercial construction in New England. As long as its kept covered it will last a lot longer than the shingles on top of it. Even if the mounts are installed poorly, this stuff will usually seal it.

If you have a layout for the panels it would be foolish not to install a roof box like this one http://www.rstcenterprises.com/soladeck/. If you are using microinverters the location isn't an issue but if you are going with a central inverter, the roof box and its associated automated disconnect needs to be within 5 feet of the panels. Even though some folks hide them under the panels, I would not as I really wouldn't want to have to remove a panel to get to it.

There is some potential cost savings if you go with a rackless system like this http://www.quickmountpv.com/quickrack/index.html. They tend to need more mounts into the roof so the a rackless system is potentially more troublesome with a existing roof but with a new roof, installing the mounts prior to shingling may be an option. If I DIYed the shingling I might consider it but wouldn't trust a roofer to make sure everything was aligned as there is not a lot of adjustability.

The other minor thing is get really good measurements on the exact center to center distances between roof joists from a known point that wont go away. Finding the center of the roof joist after the shingles are on can take awhile and its very frustrating to drill a hole and miss. A patch of storm shield will patch it over but still a PITA.

[foo1bar]

Is there anything special we should do, or ask the roofer to do, so we won't have any forehead-smacking moments while installing the solar equipment after the roof is renewed?

I would probably put down the mount points for a system - something like these:

http://www.quickmountpv.com/products/qbase-comp-mount.html?cur=0

A lot easier to hit the rafters when you can see the plywood edges and where the plywood is fastened.
And something like this I think is going to work well being installed at the time the roof is going on.

The downside is you have to
A> figure out where the rails are going before the roof is done (not a big deal IMO)
B> make sure these get installed in a nice straight (and level) line - which probably isn't too big of a deal since you can measure from ridge and eave to make sure it's in the right spot. And straight doesn't have to be completely perfect, but you'll want it pretty close. 1/4" off to either side you should be able to adjust for as you're installing rails.

Good luck.

[Chris D]

That makes sense.

The other minor thing is get really good measurements on the exact center to center distances between roof joists from a known point that wont go away. Finding the center of the roof joist after the shingles are on can take awhile and its very frustrating to drill a hole and miss. A patch of storm shield will patch it over but still a PITA.

Great advice. Thanks! I'm in Southern California and it never freezes where I live so ice is not an issue. The issue of locating the centers of the roof joists occurred to me as potentially one of the biggest pain points in the whole project. I have enough trouble locating a stud in an interior wall, much less the center of the stud.

I was trying to think of a good way to mark the center of the joist on the finished roof. Would it be ridiculous of me to ask the roofer to snap chalk lines or something similar? What do people do who are installing solar and are *not* replacing their roof?!

I have one advantage; the joists are visible from the outside of the house as they are exposed where the eaves overhang the exterior walls by a couple of feet. Still, it would be nice to know where the joists terminate at the ridge.

Hmm....

[sensij]

If you have a layout for the panels it would be foolish not to install a roof box like this one http://www.rstcenterprises.com/soladeck/. If you are using microinverters the location isn't an issue but if you are going with a central inverter, the roof box and its associated automated disconnect needs to be within 5 feet of the panels.

Disconnect types and locations may vary depending on your power company, the code of your local jurisdiction, the opinion of your fire department, etc. It is not a global requirement to have an automatic disconnect within 5 feet of the panels, regardless of inverter type.

Asking the roofer to locate the center of the rafters (not joists) with chalk lines sounds reasonable to me.

There are high quality stud finder type devices that can find the rafters through the shingles, although they aren't inexpensive. There have been other DIY ideas show up in other threads here from time to time, so it might be worth a couple of search attempts if you are looking for ideas. Use google with "site:www.solarpaneltalk.com" after your search term to get better results than the site's built-in search. With one person in the attic and one on the roof, some strong magnets can be used to locate the rafters pretty reliably.

[Amy@altE]

Make sure you talk to whoever you pick as a supplier and explain where you are, what type of roof shingles you have, the available dimensions of the roof, and any restrictions (i.e. you have to stay 3' away from edges and ridges). They should be able to design the racking and flashing that works best for you. If you are using Enphase micro inverters, the Envoy is required to set it up, not optional as that site implied. Micro's automatically comply with NEC 2014 rapid shutdown, so you don't need a disconnecting combiner box near them, just a AC junction box to transition to conduit. You'll probably need an AC disconnect like the SquareD DU221RB.

[foo1bar]

Great advice. Thanks! I'm in Southern California and it never freezes where I live so ice is not an issue.

Grace Ice and Water Shield may have "Ice" in the name - but that doesn't mean it isn't useful in snow-free areas like ours.
It's a rubbery sheet-type stuff that sticks to the plywood and gives you very good leak-resistance.
It's more expensive than tar-paper, but is likely to help your roof stay leak-free longer and help with keeping water out where you have penetrations that go through it (like nails and lag-bolts)

If you go with it, I'd check with the shingle manufacturer that they're OK with that under their shingles for the whole roof. (probably they will be, but check)
It's $170 for 225sq ft at HD - and I think it's likely worth it.
(The downside is that it'll be a PITA in 30 years when you're redoing the roof)

[peakbagger]

My install didn't need to meet the new roof disconnect rule (that as others said doesn't apply to microinverter systems). I still found that it was a great place to transition from PV wire to conduit plus it came with some fuse holders and a ground block. I hung one of the midnight solar SPD surge arrestors off the bottom edge of the box so my wire runs into the house had the maximum protection.

As for ice and water shield, yes it has the name ice in it but it works remarkable well in high wind/rain conditions. I have seen several structures where the shingles ripped off but the storm shield held tight, once it has been in the sun for few days its is not coming off the plywood. We once removed the sheathing from a roof in one piece by prying it up from the rafters from the inside and cutting it at the ridgepole, The sheathing dropped two stories and the plywood cracked rather than ripping the membrane. If you look carefully under roof sheathing that has old nail holes in it the asphalt will eventually fill the holes.

[sdold]

If you are using Enphase micro inverters, the Envoy is required to set it up, not optional as that site implied.

To set what up? The only thing I needed mine for was for on-line monitoring. The inverters worked without it, out of the box.

[Amy@altE]

To set what up? The only thing I needed mine for was for on-line monitoring. The inverters worked without it, out of the box.

Maybe they've changed it, but I've been told that they won't go online without the Envoy.

[SoCalsolar]

You may want to consider a professional

The issue of locating the centers of the roof joists occurred to me as potentially one of the biggest pain points in the whole project. I have enough trouble locating a stud in an interior wall, much less the center of the stud.

I was trying to think of a good way to mark the center of the joist on the finished roof. Would it be ridiculous of me to ask the roofer to snap chalk lines or something similar? What do people do who are installing solar and are *not* replacing their roof?!

I have one advantage; the joists are visible from the outside of the house as they are exposed where the eaves overhang the exterior walls by a couple of feet. Still, it would be nice to know where the joists terminate at the ridge.

Hmm....

If the above is true you may want to consider a professional or offer to install a neighbors house first. After that you should be better at locating studs.

[J.P.M.]

If the above is true you may want to consider a professional or offer to install a neighbors house first. After that you should be better at locating studs.

On visible roof rafters, one thing of many sometimes overlooked: long span rafters may need to be overlapped. That can put a "rafter" a little less than about 2" left or right of where you think.

02/14- corrected "joists" to " rafters".

I apologize for my error.

[peakbagger]

The joist issue is one of the reasons I advocate ice and water shield. I use a coat hanger for a drill bit for the initial hole through the roof, if I miss the joist the hole seals up and then I just move over and drill another hole. Unless I get real unlucky, it only takes 2 holes to find the joist center.

[sdold]

If you mount to the rafters instead of the joists, the screws can be shorter for the same amount of thread penetration.

[Solarnemo]

Preparation for solar - Vents

Are there any opinions on when and if panels should be routed over existing roof vents?

I am a newbie, but would think that vents should be moved or replaced with a roof peak vent.


In Minnesota, we have snow issues. Would any heat coming up through roof vents help mitigate snow buildup?