Planning solar mounting - new roof

[rugadog]

Hi ya'll,
I've been posting updates on my detached garage build and I'm at the point where the roof is getting put on soon, hinging on a few days on dry weather. I need to make a decision soon regarding the pre-planning of my roof and (future) solar panel mounting. My roof is a 12:5 and it will be tile.

I have solar on my house that was put on about 5 years ago and the contractor used the type of mounting that my roofer is recommending.

My roofer is insistent that I should go with the type of clips that can be attached later, after the roof is completed. I just want a second opinion from you guys that this is the best way to go, BEFORE I am at the the point of no return-roof completion.

Please let me know your thoughts, regarding whether there is something better than post roof completion mounting or I there is something that should be used BEFORE the roof tiles are in place.

Thanks in advance

 

[ard]

Roof mount solar *****. IMO

But unless you have all your parts in storage (mounting system, panels) I'd wait to install the roof mounts.

 

[Git]

IMO roof mounted solar is the way to go! (depending on where you live, how much space you have available, etc)

What type of mounting system are they talking about?

When I had solar installed several years ago, I extensively looked into the mounting system because most people take it for granted and focus on the panels and other hardware instead

Each mount needs to be treated as an actual 'roof penetration' and should be double flashed. Once at the roofing membrane (tar paper or whatever) and again over the actual roofing material - in my case concrete tiles

These are actual pics the installation crew took while they were installing my system.

The mounting system - this is what I would have installed. (My contractor warrantied my roof for 10 years)

https://www.quickmountpv.com/products/standard-tile-mount.html?cur=1

 

[tyme2par4]

Unfortunately tile roofing is probably one of the most labor intensive roofing types when it comes to installing solar. But unless you have the layout of the panels already planned, the roofer can't really install the mounts before hand.
As long as the mounts are installed correctly, installing them later is just fine.

 

[Git]

Yes - you would need a general idea of where the panels need to go. Rails get installed to those standoffs in my pics, so you can see it doesn't have to be an exact location

OR

You can always hire someone like this guy did. Just drill holes through the tiles once the roof is on - hopefully you will hit a rafter. Then screw in some all thread, apply a lot of caulk and sealant and move on to the next one.

 

[dcg9381]

I haven't installed on roof tile - to me it'd be the hardest install. I use unirack hardware typically, and according to a quick search, there are 6 different ways to do it with tile.

https://unirac.com/wp-content/uploads/pdf/SM_Residential-Roof-Attachments-Brochure_20190625_Web.pdf

I'd be surprised if your roofer will do solar - I'd rather see you ask the guys that are going to install the rack kit. The only possible modification I'd make is adjusting the roof decking so you're not worried about hitting studs (not that this is necessary anyway).

Last one I did at my shop, we are basically screwed through the metal roof deck into purlins.

 

[ard]

IMO roof mounted solar is the way to go! (depending on where you live, how much space you have available, etc)

OT I guess..but...

So all things equal, you prefer the roof to a ground mount?

It seems to me the sole benefit to roof is when you dont have the land. What other benefits do you find?

 

[rugadog]

Thanks for the feedback guys! I think I'll just let the roofer do his thing and worry about the mounting later, as soome have suggested. I'll try to follow the example of my solar contractor used 5 years ago when he installed.

Ard: I've only got a 1/3 of an acre. I don't want to waste any prime real estate with solar panels. Why do you dislike roof mounting so much?

Git: Those mounts look pretty extensive! I got a 10 year warranty too, but the mounts my contractor used weren't that involved. The other option you show, drilling thru the tile...that makes me cringe.

dcg9381: thanks for that brochure. I saved it for reference later.

 

[Git]

ard - I really don't see a downside to a roof based system. I actually have the room for a ground-based array - we own about 45' down a western facing slope that is about 200' long and is basically fenced off from the rest of the yard. (I installed a lodge pole fence at the top of the slope and there is a 6' fence at the bottom, so it is basically useless space) - but we never even considered it.

We have a pretty big system, 12.4 kWh DC. 39 panels total on a two-story roof. 18 panels on the South roof and 21 on the West roof. You can't see the panels from the front of the house and you have to go to the very farthest corner of the backyard to see the West panels on the back of the house. Concrete tile roof should last 50 years and I have the utmost confidence in the mounting system and the contractor who installed it. I specifically paid extra to make sure all the panels are contiguous, and not placed helter-skelter all over the roof. This involved moving roof vents and plumbing stacks, any conduit is run through the attic. I think it is a pretty clean looking installation.

Roof mount - shorter electrical run from the panels to the main panel. The majority of the work is already done with the roof mounts and the government picked up 30% of the costs. If we ever needed to replace a panel or upgrade, it should just be a matter of unbolting an old panel and replacing it. Panels are good for 25 years and by then, I can't even imagine how many watts each panel will produce. Our current panels are 320 watt LG Neon and in the course of 3 years I see they are now up to 370 watts.

What do you see as a negative in a roof mount?

 

[dcg9381]

Yes, the mounting system can be expensive. You know, all aluminum, bolt together, there there is a decent amount of engineering to it, not to mention shipping 12' sections (or whatever length they are). In some places, the tested wind ratings are required to meet code, tec. Note, you really can't buy this stuff until someone comes up with a design that deals with your roof geometry, panel size, and number of panels... And there are a bunch of different ways to configure them for tilt and roof attachment.

For many people, roof based is all they can do due to various restrictions, lack of yard, or substantial trees/obstructions. Some roofs are oriented perfectly, some not so much. I've even seen installers do both north and south sides of a roof (not sure how they sold that).

Solar is a divisive aesthetic subject. It can absolutely help a home sale or absolutely kill a home sale, depending on the buyer. I know people that "can't stand" seeing panels on the roof of a home and those that couldn't care less... And people that love what these systems do for energy bills.

I largely do ground based arrays - partly because they are allowed, partly because I can fixed pitch and orient them right, and partly because I don't like working on roofs. Most of where I work is "sparse" residential - so lots are 1/2 acre or larger.

The last install I did (for myself) was on the shop shed roof because the developer wouldn't allow an array in my yard (2 acres). You cannot see the panels from the road or anywhere else (roof eve is at 16'). And frankly, you wouldn't have been able to see my array from the road either.... But I didn't fight it.

The other advantage to a roof array is that it's much harder to steal. At $300 per panel (or so), 4 bolt attachment, at best - it's a lot of money sitting in your yard and it's pretty easy to unbolt it in put it into a truck..

 

[LS6 Tommy]

You couldn't pay me to put solar on my roof regardless of installation method or roof type.

Tommy

 

[dcg9381]

Well, it does pay.. But fair call. It's not for everyone. Kinda like Fords.

 

[LS6 Tommy]

Well, it does pay.. But fair call. It's not for everyone. Kinda like Fords.

It's not for everyone for sure. It's also not for anyone that likes their roof to stay intact and not grow mounds of green **** on it.

Tommy

 

[azmodela]

You couldn't pay me to put solar on my roof regardless of installation method or roof type.

Tommy

Me either. Roof penetrations are future leaks, as I chase on my current house every year. I'm going to build my next house rather than buy one done. My next house will not have any roof penetrations, everything will be vented or exhausted from the soffit or wall.

Can you build a carport or other cover next to the garage? Put it on there, and park your trailer under it, or other equipment.

 

[zmotorsports]

You couldn't pay me to put solar on my roof regardless of installation method or roof type.

Tommy

Same here. I managed the installation of the second largest roof top solar system in the state of Utah several years ago at work and there is no way I would put solar on my property.

It's definitely NOT for everyone. Future roof repair(s) plus the shear weight is enough to sour me.

 

[ard]

Ard: I've only got a 1/3 of an acre. I don't want to waste any prime real estate with solar panels. Why do you dislike roof mounting so much?

ard - I really don't see a downside to a roof based system.


What do you see as a negative in a roof mount?

- Rarely does the roof have the right ORIENTATION and TILT for optimal exposure. I mean virtually never.

- Unless you have a flat, large expanse of a rectilinear roof, you will be placing a 'pattern' or panels around the roof. You can change a nice looking roof, with interesting angles and planes into a distored checkerboard.

- Change the roof, you need to uninstall the solar.

- I assume the solar install doesnt cause leaks....

- Drilling a bunch of holes, concreting in 2" sch40 galv, is super easy. Some say a push to climbing on the roof, disassemble the tile, install mount and water proof..then re-assemble...then build the rack. But lets say a push


I will grant this: If you dont have the land, then that's that.

 

[toplessHO]

I too have been pondering this in the planning stages.
My roof needs redone,along with some of the sheeting
so Im thinking of making a drawing with some exact measurements
off of a plumbing vent and at 5 ft centers running with joists,adding a cripple
in case I ever want to add panels.
I may add blocking across the joists also depending on how the layout is.

 

[ard]

Anyone interesting in optimizing solar production...

https://www.solarpaneltilt.com/

https://www.wholesalesolar.com/blog/solar-panel-azimuth-angle/

http://www.solarelectricityhandbook.com/solar-angle-calculator.html

my recollection is that even on a perfect south facing roof, having the wrong tilt (ie the roof pitch isnt optimal for your latitude) you can toss away 20, 30% over the year. And if that roof isnt perfect south, toss away another **%.

Installers love roof mount- easy, one crew, no concrete. And every house has a roof, no matter how poorly situated for actual solar yield.

 

[PelicanPines]

I had an accountant and a former solar panel company accountant confirm... you are nuts if you mount solar to your roof... yard mount it or forget it.

 

[Git]

I had an accountant and a former solar panel company accountant confirm... you are nuts if you mount solar to your roof... yard mount it or forget it.

I have to ask. Why would an accountant know anything about mounting solar panels on a roof?

What happened - you guys get tired of the Tesla Truck thread?

 

[PelicanPines]

I have to ask. Why would an accountant know anything about mounting solar panels on a roof?

What happened - you guys get tired of the Tesla Truck thread?

Liability...

If you have solar panels... roof leaks... I bet you think you are covered by the solar company... they will say you are covered. Accountant knows from experience, from their home owner clients and business clients... you aint covered. (from doing the loss statements for tax purposes)

Need a new roof and your panels still work in 10 years... guess what... you have to get your new roof thru the solar company because no roofing company would take on the liability of screwing up a solar install. Solar company will "say" all kinds of comforting things... get a quote from a reputable roofing company and we will do it for that price... BS, in 10 years... the solar company isn't owned by the same people. Your written agreement is null and void.

Basically … accountants know about solar panels on roofs.

 

[Git]

LOL, I can't tell if your actually being serious or not

Just in case you are, two thoughts come to mind. You New Jersey guys must have some really terrible contractors/roofers that really don't have any idea what they are doing. And secondly, the contractor I hired for my Solar - has been in business for over 80 years! They aren't going anywhere. They have their own electricians, they have their own roofers. They are all union workers who busted their butts and got the job done. They even took photo's of every step of their work to document how they did things.

I know some of you guys like to hire those gypsy driveway sealer types who just happened to be working around the corner and have some extra material left over...

I can see it now - hey buddy, we were working the next street over and we have some extra solar panels and can cut you a heck of a deal....

How does this leak?

 

[PelicanPines]

Serious... If I was joking... I would end it with Bazzinga…

And that is not a typical NJ solar install... or roof in NJ

Here they just drill right thru the roof material... they say they will drill into the beams only... they lie...

Never heard of a solar company being in business 80 years.

 

[Git]

I forgot to add the finished pic. See that vent stack, they even had a guy come back a couple of days later he painted it

Didn't hire a fly by night 'Solar Company'. I hired a commercial electrical contractor

 

[ard]

Git-

What is the pitch on that roof? What is the angular orientation to that roof off due south?

I'll go ahead and calculate how much power you left on the...uh...roof.


This isnt a ******* match- or it shouldnt be. If you recall in my comments above I grant that you can get a 'perfect' roof install- and Ill grant that 'because some hacks mess up installs' is not a valid reason to not chose one or the other. Yours is obviously super clean

My point in posting is to educate people on the tradeoffs. In fact, I would bet $$$ that many people think "man, there are a ton of roof installs so why is ard saying you can lose 20, 30, 50% of the power over a year"??? Like, how can this be true???

It is.


For example, down there in long beach, the optimal pitch on a south facing roof is 32 degrees in the winter and 80 in the summer. (Just from memory) If you are chosing a fixed pitch it is 56 degrees. Which is like 11/12 pitch.

So is your roof 11/12?

Looks like 6/12? So your roof is optimized for summer production. (when, due to ambient temps, solar cells are less efficient) In the winter you are way down compared to a properly tilted array.

Again, there is some engineering involved with this stuff- but once you say 'that roof, that pitch, pointed in that direction' you may have traded off a massive amount of solar generation.


Finally, clearly your installers did a solid job. I know it feels like me and pines are picking on you- im just trying to add info others might not think about.

And I didnt post in that cluster called 'tesla truck thread'...

 

[frank001]

Yes - you would need a general idea of where the panels need to go. Rails get installed to those standoffs in my pics, so you can see it doesn't have to be an exact location

OR

You can always hire someone like this guy did. Just drill holes through the tiles once the roof is on - hopefully you will hit a rafter. Then screw in some all thread, apply a lot of caulk and sealant and move on to the next one.

These look like the exact type of roof tiles that I have. I wouldn't even think of drilling through them to install some **** fasteners like those, and make a probable leak location. Only a matter of time. Another reason I'd never get roof mounted solar. Plus those solar panels just look awful on a house.

 

[frank001]

You couldn't pay me to put solar on my roof regardless of installation method or roof type.

Tommy

^^^^^^^^^^

 

[frank001]

I forgot to add the finished pic. See that vent stack, they even had a guy come back a couple of days later he painted it

Didn't hire a fly by night 'Solar Company'. I hired a commercial electrical contractor

Ruined the looks of your roof.

 

[code4pay]

interesting here in Australia 21% of homes have solar as do I and it is all roof mounted. we don't get snow obviously so that could make a difference with roof penetrations. since it is so popular here it has no negative effect on house prices generally the opposite.

Mike

YouTube

 

[dcg9381]

Again, there is some engineering involved with this stuff- but once you say 'that roof, that pitch, pointed in that direction' you may have traded off a massive amount of solar generation.

This is definitely true. And you can calculate how much energy you're leaving on the table based on your actual roof pitch compared to optimal fixed pitch. But again, lots of people don't have a choice to ground mount.

I did my own last install and chose not to re-pitch the panels on the roof because the cost of the hardware, compared to the 15% or so efficiency gain - it just wouldn't pay back soon enough for me. It's all a compromise.

The worst people in the solar industry that I see are those selling "zero cost" leases. The lease has a fixed cost and they typically tell homeowners that their power reduction costs will exceed the cost of the lease. In many cases, turns out not to be true....

 

[Angelfire]

I have solar on my roof and have been quite happy with it. Of course, I have a very different roof than what's being discussed here. TPO over a flat roof with sizable parapets makes the install invisible to anyone on the ground and no penetrations. Unirac mounting system is used almost exclusively here. Of course this probably doesn't help the OP one iota given his very different situation. Just pointing out that some of us live where houses are built differently and mounting on a roof makes perfect sense.
Cheers.

 

[tyme2par4]

For example, down there in long beach, the optimal pitch on a south facing roof is 32 degrees in the winter and 80 in the summer. (Just from memory) If you are chosing a fixed pitch it is 56 degrees. Which is like 11/12 pitch.

So is your roof 11/12?

Looks like 6/12? So your roof is optimized for summer production. (when, due to ambient temps, solar cells are less efficient) In the winter you are way down compared to a properly tilted array.

Again, there is some engineering involved with this stuff- but once you say 'that roof, that pitch, pointed in that direction' you may have traded off a massive amount of solar generation.

That is not correct. As a general rule, your optimal output angle is going to be equal to the latitude at your location, or slightly less. So Long Beach, CA would be 30 degrees. So a 6/12 pitch is going to be pretty close to optimal.

And as far a losses from not being due south, you really only lose a few %. Even being 30 degrees off, in Long Beach you would only lose about 3% efficiency.

Also now that a reread your post, you seem to be measuring angles the opposite of everyone else. 80 degrees in summer should be 10 degrees. You measure from the horizontal, not from the vertical.

 

[CJ7VFR]

...You New Jersey guys must have some really terrible contractors/roofers that really don't have any idea what they are doing...

True, very true. As well as it coming down to playing the blame game.

The solar people get a roofing company as a sub-contractor to install their product on your roof. Said roofing company is made up mostly illegal aliens, none of which can speak a word of English. So you can't get them to tell you what the hell they are doing, or if they are doing it right.

They proceed to make holes in the roof, and install the brackets much like the ones in your pictures you show in post number 5 of this thread, which is absolutely the wrong way to do it, and is a sure way to get leaks.

Then, when it leaks, and the home owner wants it fixed under warranty, the solar people say uh, no, not us, we didn't install it. You have to go after the roofer.

The roofer, if you can actually find them, say, uh, no way amigo, we did what the solar people said and installed it the way they said. So you have go after them.

Leaving the home owner with a leaky roof, thousands of dollars in interior damages due to water penetration, the need for a new roof, and no where to turn for weeks, even months, while they sue both the solar people and the roofer.

So yes, New Jersey must **** ***. If the pictures of the wrong way to do it was done where you live, then you too have some **** *** contractors too. They are everywhere, not just in New Jersey. We just seem to have an over abundance of them.

Jim

 

[Git]

The pic of the 'way not to do it' I think is actually from Arizona - but I am sure there are installations like that in California also. People get too hung up on the cost of the system and the panels, and never even think about how everything is mounted to the roof.

That pic is from a homeowner who hired some hack and it went sideways on him. He ended up firing the guy, redid everything himself and ended up in the solar business. Very interesting thread which shows both how not to do it and the right way to do it in the end:

https://www.solarpaneltalk.com/foru...eally-bad-looking-for-some-help-advice-please

ard - as dcg pointed out, it's not about getting every kWh from a system. In most cases, it is just not worth it. And, a ground-based system needs to have the panels re-oriented about 4 times per year if you're after every last kWh (I am not).

The 21 panels on my West roof produce the same amount of electricity as the 18 panels on my South roof. Cost me about $1k for those three extra panels, but the Federal Government picked up 30% of it. Also, the energy from West facing panels is worth more money once you get into the Time of Usage rates. (The highest cost of electricity for me is between 4 and 9 PM when they charge $.41 per kWh!) So while my South panels are winding down in the evening, the West panels are still producing electricity.

Lastly - my utility company (SCE) has limits on solar. The most I could install was 120% of the previous years usage. And, if we don't use all of it (over-generation), the utility will pay me a measly $.02 per kWh. Again - not worth it.

frank - As is said before, the panels can not be seen from the street or back yard. But what I do see is the $350 per month (average) in electricity they are making for me. To each his own...

 

[Git]

LOL, just found this site:

New Jersey's Ugliest Solar Installations

 

[ard]

That is not correct. As a general rule, your optimal output angle is going to be equal to the latitude at your location, or slightly less. So Long Beach, CA would be 30 degrees. So a 6/12 pitch is going to be pretty close to optimal.

Odd.
My reading seemed to indicate you split the winter/summer difference, but maybe 'cheat' a bit to optimize for summer since there is more flux then.

And as far a losses from not being due south, you really only lose a few %. Even being 30 degrees off, in Long Beach you would only lose about 3% efficiency.

Technically you can cheat a bit towards the morning sun, since panels are more efficient in the cool AM.

I agree that you can tolerate quite a bit on this axis...

But as you can see, the tilt is more sensitive that southern (azimuthal) alignment.

Also now that a reread your post, you seem to be measuring angles the opposite of everyone else. 80 degrees in summer should be 10 degrees. You measure from the horizontal, not from the vertical.

I though 90 degrees is sun overhead, no? if I switched that somewhere, my bad. Converting panel angle to roof angle you do need to flip.


Git- great hall of shame...

 

[CJ7VFR]

LOL, just found this site:

New Jersey's Ugliest Solar Installations

That is pretty much why I will never put solar panels on any roof of any home I own. I have yet to see, in person, an honest to goodness solar panel install job that was well done around here.

I have several neighbors who got taken probably by the very solar scammers that did a lot of those horrible installations in the link you posted.

One neighbor is still fighting, in the court system, both the solar company and the El Chavo installation company that put them up. My neighbor is out tens of thousands of dollars for water damage repairs, roof repairs, and some electrical repairs.

I am glad you were able to get someone who knows their ****, and did a good job, and I hope your long term usage of the system lives up to the costs you laid out for it.

But for me, I will never have a roof top solar system installed. I would only ever do a system that could be installed on the ground and not introduce holes in my roof.

Jim