OMG WHY IS WATER COMING THROUGH OUR CEILING!!!
The fear about roof penetration from solar installations is definitely in the top 3 concerns of people that are serious about installing solar power, so let’s just clear the air. I don’t personally know how every company installs solar energy panels on a roof, but I know how our company does it, and that is what I’m going to explain in this article. I also know that some people shouldn’t be doing it at all.
Installation practices vary by roof. Spanish tiles are the most expensive type roofs to install PV modules on. The reason is that we have no choice but to walk on them, and inevitably break some of the tiles. The owner must have extra tiles lying around, or we must be able to find a match ahead of time to be able to replace. If not, we cannot do the job. There is also some added time spent both drilling through them and treading carefully upon them. Wood shake shingles are particularly awful as well. The easiest and thus cheapest type of roof to install solar energy on is a composition roof.
There is a unique benefit to the flat, tar-and-gravel roofs and the flat polyurethane foam ones, because you can aim the photovoltaic modules in any orientation or tilt you desire, although to build that scaffolding to put them on costs a few bucks extra. With a pitched roof you are often limited to the orientation and tilt provided by the roof, which, if perfect already, is going to be cheaper than doing a flat roof.
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| Spanish Tile |
Tar and Gravel |
Wood Shake |
Composition |
We use something called “fastjack” to attach to the roof. Fastjack is made by pro solar. Then we seal the crap out of it with this stuff from GeoCellUSA.
Here are some notes:
- Yes, we stick giant lag bolts into your beams like the one with fastjack in the picture above.
- Panels aren’t that heavy. Most of the coding requirements come from “upforce.” Basically there is way more danger to the panels catching air like a sail and ripping off your roof than there is to them weighing too much and pushing through your roof. If they are bolted to the rafters then they are attached to the infrastructure of your house and not the roof, and there are no worries.
- We’ve never had a customer have a leaky roof because of a solar installation we have performed, and we’ve been around 30 years. The sealant we use is very high grade and warrantied for 50 years.
- A huge amount of labor is spent finding the exact center of the rafters. There are new mounting products coming out that will reduce this labor.
- We can coordinate with a roofer so that we come in and put the posts in, they do the roof, then we come back and do the install.
- It’s about $1000 bucks (of course that could be less or more based on size) to pop off existing panels to let a roofer do his thing, and then put them back on, so never let doing your roof stop you from getting solar. It’s almost always better to start saving money on energy today.
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What do you recommend for a flat tar roof as far as attaching the mounting system? and what are the best ways to get the exact angle needed for maximum efficiency. In the Southeastern US
TC,
We recommend ensuring that whoever is up on your roof doing the installation knows what they are doing. Fastjack bolts or similar need to be drilled directly into the joists in your flat roof. That can take a little bit of time. Optimum panel tilt depends on your latitude. If you’re in the Southeast US, I’d say something like 20-30 degrees. Check this with local installers though. Orientation = south.
the racking system we used to use only went to 12 degrees if you stuck two panels in portrait. You’d be surprised how little difference optimal tilt matters as long as you’re withing 10 degrees. More important than tilt is orientation, and WAY WAY more important than orientation is shading.
for perfect tilt, do a google search for magnetic declination. Like I said, perfect tilt matters almost nothing. in SE just shoot for 15 degrees or around there.
FYI
I find that when people use special racking systems that allow for a summer/winter adjustment… they end up saying ’screw it’ and never adjust the thing, leaving it optimized for summer or winter year round.
We have a flat roof with a EDPM rubber over high density foam that is 3-4″ that is screwed into the plywood overlay. It is a two story modern contemporary house. We have an unobstructed southern sunshine that can generate a lot of solar energy. I’m afraid that if you anchor the panels to the EDPM there will be leakage. What is your solutions if there is one for this type of structure?
Tilting the panels is our biggest problem. My husband and I are just too old to be climbing up there to do such things.
Here is a great article on solar panel tilting which I found helpfull.
http://mymilescity.com/how-to-solar-power/tilting_solar_panels.html
Hi David:
Thanks for your useful articles. At the beginning you mentioned that leaking is one of top three concerns of your customers. Can you please let us know what two other concerns are? Thanks
Hi David:
I am about to install a 4 kw solar Do it yourself system. I have done lots of reaserch and i would like to use the pro solar fast jacks for mounting to our s-curve concrete tile roof . I under stand about removing the tile and mounting the fastjacks to the rafters and then sealing , but what is the best way to do the flashing,, do you drill a 1″ hole in the concrete tile and then use metal flashing,, thanks for your help
Randy
[...] How are Solar Panels Attached to my Roof? [...]
[...] How are Solar Panels Attached to my Roof? [...]
I appreciate the info that I read on here.
I am about to install (or possibly have installed) a 10kW system on my roof that is almost 60′ long. Do you have any suggestions how to ensure the installation is quiet and that I do not have expansion or wind noises from the aluminum framing? Also, is there a minimum distance off of the roof that the solar panel needs to be mounted for heat dissipation? I am trying to learn everything well in advance and appreciate any advice. Lastly, I cannot fit enough Sharp panels so I am looking at Sunpower and Sanyo which have smaller footprints. Any suggestions or alternate companies?
Thank you,
Steve
Steve, I’ve never heard of anyone complaining about wind noise from solar. Never. If the wind in your area is blowing that hard, it’s going to make noise no matter what.
Your panels must be installed with framing a certain amount above your roof, that’s true. I’m really not sure of the minimum amount. However, you are right: Panels like to be cool and work best raised above the roof line. Having them flush against your roof is a no-no, even if it looks “better” more flat. That being said, it’s a typically minimal amount above your roof.
Good luck with the install and thanks for going Solar! You rock.
TC
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Tor a.k.a. "Solar Fred"