Solar panel mounts

[andyvh1959]

I have a four 220 watt panel system going up on the south hip of the roof of my shop soon. The south hip has a 10/12 pitch so the panels can mount direct to the roof without angle mounts. Its a stand alone 12v system with four battery backup to power the 12v LED lights and motorcycle charging ports. I already have the breaker combiner box and charge controller. So I just need to mount the four panels to the roof, up here in Green Bay WI.

With the steep pitch I figure the panels can just be spaced off the roof a few inches. This is a snow belt location, averaging about 50" of snow over from December to late March, but most often the snow on a unheated roof with a 10/12 pitch is minimal. My question is if anyone has a similar application of solar panels and should I plan for a higher offset for the panels off the roof. This style of panel mount is easy to find and reasonably priced:

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Perhaps add a section of 2x2 aluminum tubing under each mount to space them higher off the roof?

 

[Sumboodie]

4 panels for 220 watt? The panels I had on my old house were about that each panel. Now they are closer to 300 watts a panel.

You use solar panel racking to mount to the roof. That will have the panels 3-4" off the roof deck.

 

[andyvh1959]

Yes they are 220 watts each, so I'll have 880 watts of 12v power from the four panels. I have four large 12v batteries in the system that will be the storage side, from which I calculated I can run the 12v LED shop lights constantly for 20+ hours with no additional power from the panels. So I expect the panels and batteries will meet the load I plan for the shop. This is a stand alone system, my 1st go at solar so I can learn from the system as I go.

With the 12/12 roof pitch the panels will be about 13 degrees back from the optimum angle to the sun for the northern location of Green Bay, at 63.6 degrees for the winter sun. But I'll settle for the panels parallel to the 12/12 pitch angle of 50 degrees for a simple instalation.

 

[Sumboodie]

Yes they are 220 watts each, so I'll have 880 watts of 12v power from the four panels. I have four large 12v batteries in the system that will be the storage side, from which I calculated I can run the 12v LED shop lights constantly for 20+ hours with no additional power from the panels. So I expect the panels and batteries will meet the load I plan for the shop. This is a stand alone system, my 1st go at solar so I can learn from the system as I go.

With the 12/12 roof pitch the panels will be about 13 degrees back from the optimum angle to the sun for the northern location of Green Bay, at 63.6 degrees for the winter sun. But I'll settle for the panels parallel to the 12/12 pitch angle of 50 degrees for a simple installation.

My system made minimal power from October to March. The sun is just too weak here in the winter.

 

[Cougar]

Where did you buy the panels.

 

[ipgenie]

I don't think the distance between the panels and roof will matter in this case. With those brackets It's basically the same as a million RV solar installs of varying watt sizes. The air gap is mostly for cooling air flow.
Your 12/12 pitch should shed snow easily and at that angle should produce about as much Winter power as is available.
You would have to use UL approved racking if inspections were required. For off grid, not on your home you probably don't need to worry about that but it wouldn't hurt to check with your county/state.

 

[andyvh1959]

Good points and thanks. I framed the rear hip of the garage roof with the intent to need minimal mounts for the panels, and the angle would suit shedding snow like you mention. Since the basic mounts work for RVs the same mounts should be fine for my stationary garage (won't be moving at 70moh any time soon). I talked to the electrical inspector about my stand alone system when he did the final approval of my 120/240v wiring for the garage, and Green Bay really has minimal requirements for any stand alone solar, so I am good to go. I already have a combiner box (which features internal breakers and disconnect switches) which is labeled for the solar circuits.

 

[reader2580]

I’ve never seen residential solar mounts that are tilted more than the angle of the roof. I am sure it happens, but I have never seen it. I had my solar panels on my detached garage with 4/12 pitch and just laid them against the roof with no additional tilt. (I moved the panels to ground mounts due to future demolition of the garage.)

 

[nadogail]

From what I have read about Solar Installations your latitude will influence the optimum collector mounting angle.

 

[dcg9381]

I’ve never seen residential solar mounts that are tilted more than the angle of the roof. I am sure it happens, but I have never seen it. I had my solar panels on my detached garage with 4/12 pitch and just laid them against the roof with no additional tilt. (I moved the panels to ground mounts due to future demolition of the garage.)

You can do it but you end up building mounting systems (for more than one row) that are essentially a frame on top of the roof.

OP for small panels those kind of mounts are pretty standard (RV applications, etc). You can also look into "rail" systems, but for 4 panels it's probably overkill.

 

[grounded-b]

You will need some sort of flashing where the mounts attach to the roof. Typically you mount a "post" every 4 feet, landing on a truss or rafter. Then you span the posts, horizontally with a framing member. Then you attach "clips" to the horiz rails, to hold the panels in place

Steve

 

[WisJim]

Looks like those mounts mentioned in the first post get the panels about 3/4" above the roof which isn't a lot. You probably want more than that to ensure some air circulation between the roof and panels to keep the panel temperature down. And, as mentioned, you want to do a good job of flashing as that has been something that was often overlooked in installations in the past. I'm in Western Wisconsin, and I have found (over the 40+ years that I have been using PVs) that my PV system has put out the most power on sunny but cold February and March days when there is still snow on the ground which reflects more light on the panels; the efficiency of the panels goes up as the temperature goes down.

 

[reader2580]

I used Quickmount PV flashings on my garage roof in 2017 or 2018. A little more expensive than other options at the time, but no leaks. I moved the solar panels off the garage to a ground mount in 2020, but left the flashings in place since they don't leak.

The latest trend for roof mounts is something called micro flashings. They basically mount on top of the shingles and depend on sealants to keep things dry. I wouldn't want that, but it is less labor to install and that is what solar companies care about these days. A metal flashing is always preferable to sealants and caulk in my book. Sealants and caulks almost always crack and leak over time.

 

[Chuckster in NJ]

In New Jersey you must obtain a set of engineered (NJ sealed) drawings or letter for attaching the solar panels to make sure the roof can handle the extra load.…… Yeah, I know it’s BS, but that "is the way it is" if you want a required electrical, fire and building permit.

 

[reader2580]

In New Jersey you must obtain a set of engineered (NJ sealed) drawings or letter for attaching the solar panels to make sure the roof can handle the extra load.…… Yeah, I know it’s BS, but that "is the way it is" if you want a required electrical, fire and building permit.

My city also requires an engineer to make sure the roof can handle the load. I previously had solar panels on my detached garage roof and the city didn't even require a building permit or engineered drawings when I installed those in 2017 or 2018. Now, a building permit is required and it needs the engineering approval.

 

[Chuckster in NJ]

My city also requires an engineer to make sure the roof can handle the load. I previously had solar panels on my detached garage roof and the city didn't even require a building permit or engineered drawings when I installed those in 2017 or 2018. Now, a building permit is required and it needs the engineering approval.

I have done many plan reviews for municipal permits where the engineer has provided sealed drawings for "beefing up" roof rafters, trusses or other structural reinforcing to support panels.