Roof Noises after Installation

I actually expected this might be an issue after my panels were installed due to the metal frames expanding and contracting at different rates but things have been very quiet here. I also worried about TV reception as we only use over-the-air signals and my piddly little antenna is in the attic under all the panels but even that was not affected.

Happily, no noise issues with a wood framed truss roof, OSB deck, asphalt paper and cement tiles here in Phoenix, AZ.

That makes number 46 on my list of ground mount advantages. Bruce Roe

Did you already count the possible TV reception issue or is that #47?

It might go on my list of poor antenna installation practices. Lots of ant here. Bruce K9MQG since 1958

We've done over 300 installs, almost all on roofs - and have never heard this problem occur. Have see plenty of less than perfect roofing done however. I suspect you have a roofing issue that has been exacerbated by the solar mounting. Its quite common for the decking nails (or staples) to miss hitting the framing which would allow the decking to move and make noise. Get in the attic and inspect all the fasteners if possible, or hire a home inspector (they are good at being nit-picky) to check it out and go after whoever was negligent to fix it.

Just guessing here but could it have anything to do with the length of the array? Several years ago I provided some oversight on a city ballast mount set of arrays that were over 100 feet and the installer provided for some expansion of the rails due to temperature expansion and contraction.
Question for the OP, how long is your array?.

It would very much have to do with the length and if the rails had expansion joints. All of the major solar racking manufacturers have expansion joints and specifications on the required distances of them to be installed. That does NOT mean that the installer put them in though.

For Ironridge it is rails over 100 foot length need to have the expansion joint (see page 7) http://files.ironridge.com/pitched-r...ion_Manual.pdf

pneal , how long are your arrays?

Thanks so much for your responses.

Ampster, I have panels installed in 2 locations on my roof. The first location has 3 arrays and the second has 2. I'd have to get up there and measure to be sure, but if I had to guess, I would say the length of the first location is about 25'-35' and the second location is about 20'-30'.

solarix, forgive my ignorance. How many spacers should there be between the plywood decking? Just want to know what to look for. Can they be added after the fact, or only at installation?

one thing, the roof made no noises before the install. Would the spacer theory still work?
thanks again, everybody

Some questions: What are array dimensions, L X W ? How old is the building ? Any roof work since building construction ? What's the array to roof deck clearance ? Racking attachment type - clips, posts, whatever ?

While relative dimensional changes due to thermal expansion/contraction between panels and racking and racking to roof are usually checked, depending on the physical situation as questioned above, I'm wondering if the expansion noise (if thermal expansion is the cause) might be due to the roof under the array being at a different temperature than the rest of the roof, and the roof itself is what's creaking.

Racking, even when black, doesn't get that warm mostly because not much of it is exposed to the sun, and the rails are usually in pretty poor thermal contact with the panels meaning most of the heat transfer from panels to rails will be from thermal radiation from the back of the panels to the rails. Also, racking rails, by their very configuration make a pretty good fin for heat transfer which helps keep them cool(er) than if they didn't have all that nice surface to transfer the thermal radiation gain to the ambient air circulating beneath the array.

Anecdotally, I'm on my roof and around my array on most sunny days close to the time of minimum solar incidence angle on the array and I've observed, but not measured (yet !) that racking rails are probably about 10 C warmer than ambient at the ends and maybe 5 C or so warmer than ambient under the panels. Now, my array has enough clearance under it to allow me to get under the array (~ 10-12" or so) so that may help keep the rails cooler, but 4-6 " clearance will probably do almost as well for rail cooling.

So, for the OP's situation, maybe it isn't rail thermal expansion relative to the roof that's making the noise (and not necessarily so much the noise as possible induced stresses from possible thermal expansion.

Under sunny conditions at min. incidence angle, the temp. of the deck surface under my array is usually somewhere between the array cell temp. and ambient temp.

A typical example of several hundred such measurements:

Date: 08/15/2015. Time: 1253 P.D.T.
Temp. adjusted GHI: 905 W/m^2
POA irradiance: 955 W/m^2.
Wind vector: 1.9 m/sec, bearing WNW.
Amb. air temp. at the array: 40.7 C

Solar exposed roof deck temp.: 81.1 C
Roof deck temp. under array: 54.7 C
Average back of panel temp.: 68.0 C
Average array cell temp. of 16 panels each measured in 4 random places, 2 times ~ 8 min. apart : 70.9 C. (range 66.1 C to 74.4 C., leading to trailing edge ) - a long, boring detailed description on request.

The roof is flat, lightweight concrete tile, med-dark brown in color.

Note the ~ 26 C temp. diff. between the roof deck exposed to solar radiation and the roof deck under the array.
The OP's particulars are different, but the driving forces may well be similar and, depending on the array to deck clearance, array dimensions, roof condition, age and racking configuration, and the OP's statement that the noises "sound like popping and creaking" and "sound like wood on wood", as well as the dearth of reports of noisy arrays, maybe it's the roof and not the array making the noises.

Or, maybe something else, or several things acting synergistically. Hard to troubleshoot or analyze without being there or at least some pictures.

Take what you want of the above. Scrap the rest.

J.P.M. Wow, thank you so much for your thorough and thoughtful reply. As soon as I get a chance, I'm going to take some measurements and pictures and post.

These responses are by far the farthest I've gotten with this issue. I have spoken to my installer again and again with no results. Really appreciate the input here.

Another side of this is the pure frustration and discomfort of hearing your roof make noises at all hours of the day and night. You spend all this money, think you're doing something good, but then the quality of life actually goes down a bit. Very concerning.

I'm also concerned about leaking. To my mind, hearing noises means that things are moving, and if things are moving it stands to reason that they are getting loose. However, I haven't seen any evidence of leaking so far.

I can understand noise at warm up, and cool down, but all night sounds unusual.

Part of that might depend on thermal time constant of the various components that are producing the sound(s) and also (but not taking the analogy too far), not too much unlike earthquakes and the nature of the stability of the fixations of structures that jerk rather than slide.

You're most welcome. Just remember to not confuse conjecture and brainstorming (or brain farting) with reality. Mine is but one opinion or set of thoughts, I'm not there, and that opinions are like noses: Everyone has one, they're all different, and most smell at least some of the time. Also, none of us is as smart as all of us. Get more opinions and question everything everyone says - including me - until you understand what's being offered.

You're installer may want to help, but resources are limited. Get self reliant. You'll be disappointed less and you'll be limited in who to blame. You'll also get to a resolution quicker.

BTW, how loud are these noises ? Loud compared to what ? A toilet flush ? A door slam ? etc. Any perceived structural vibration ? Any temporal pattern(s) ?