Solar panels (PV) on EPDM roof

[Shawn Pixley]

I have a commercial grade EPDM, Single Ply Membrane roof on my house (Flat Roof). We are looking to put PV solar panels on the roof to lower our energy costs. The sales people for the solar wanted to just anchor the PV panels into the roof joists and seal the pentrations with sealant. I feel that is unacceptable and will void my roof warranty. I am trying to connect the roofer with the PV people. To get the proper flashing instalation.

I think the right solution is to build a curb with the proper flashing / counterflashing wrapping the EPDM up the curb. This would be similar to the way HVAC units are installed and flashed on commercial buildings. Has anyone here done this or have any pertinent advice?

[Mike Lassiter]

Offering only advise here, no experience with it personally.

I agree with your thinking. At some time in the future you will probably have to reroof and having them fastened on top of your existing roof would mean pulling everything up to do that. I see lots of pictures showing panels on roofs and while I think they offer a large area to place them out of the way in a sense, what do you when you have to replace shingles or whatever roofing material you have?
Sitting up on an elevated curb type base raised up some above the roof would possibly save a fortune in labor to take everything off the roof in the future.
Would having them elevated off of roof more than they typically are mounted on brackets create problems with wind getting under them and wanting to lift them. Something large and flat in a high wind has a lot of pressure potential. Being close to roof possibly only downward pressure on the roof, rather than a lifting force that would be harder to allow for I think

[Prashun Patel]

We had solar installed at my company 4 years ago. I can tell you that even more annyoing that the SREC market in NJ has collapsed is the fact that there are forever leaks in our aluminum, standing seam roof.

The problem is that solar panels are basically big sails. They catch wind and vibrate in a way that (I bet) NO sealant or roof membrane will resist permanently. If you don't get a lot of wind, or have a very small array, perhaps this is manageable.

I'm one data point, but I would not do it again if I had the chance.

At the very least, you should demand an extended warranty for any leaks your roof incurs. Don't believe their insistence that they know how to make it bullet proof. I just don't think it's possible, unless you install them on the ground.

[Jerome Stanek]

See if they can install pitch pots for the legs of the panels.

[David Weaver]

No personal experience, but I would have guessed what prashun says, though here the bigger concern might be snow, than wind.

You could certainly offer the roofing company a few bucks to come out and tell you what they think, they'll tell you right away whether or not they'll honor everything. If it were me, I'd want to have the panels attached to something other than the roof, but that's probably not very realistic. They aren't common around here because we have very crappy annual sunlight hour numbers. Further east, they're a bit more popular, but not on house roofs - either freestanding or on barn roofs (where minor leaks aren't so catastrophic).

[Shawn Pixley]

Prashun,

Your point about wind is apt. We are on the beach, so most days we get a 15 to 20 mph breeze onshore. Gale warnings several times a year. A couple of times a year we will get full storm warnings with 50-60 mph winds. The thinking is mounting it at an 18 degree angle. Worse, if improperly anchored, it would blow off and damage a neighbor's houseas well

Uplift and lateral force are definately real issues on which I need confidence in the solution before I sign. The sales people speak of 10 or 25 year warranties but I remain unconvinced especially when I see they have no clue as to what the roofing material is. I can see a situation when we discover a leak and it ends up as a finger pointing exercise between the roofer and the solar company.

Shawn

[Shawn Pixley]

No personal experience, but I would have guessed what prashun says, though here the bigger concern might be snow, than wind.

You could certainly offer the roofing company a few bucks to come out and tell you what they think, they'll tell you right away whether or not they'll honor everything. If it were me, I'd want to have the panels attached to something other than the roof, but that's probably not very realistic. They aren't common around here because we have very crappy annual sunlight hour numbers. Further east, they're a bit more popular, but not on house roofs - either freestanding or on barn roofs (where minor leaks aren't so catastrophic).

David,

Thanks. I have a call into our roofer. I want them to weigh in to whatever solution we would go with. I am absolutely willing to pay extra to the extent of doing it right.

In many ways, we have an ideal situation for solar. High electricty rates. At tier 4, the rate is $0.36 / KWH. I am sure the rate will rise in the future. With our neighborhood, we have a lot of vacation rentals so the KWH base is artificially low. The roof is flat and unobstructed to the sky. We are in a southern lattitude with more solar hours per day. Unfortunately, our lot is only 3500 SF, so putting it on the ground isn't an option.

[Jeff Erbele]

I have a commercial grade EPDM, Single Ply Membrane roof on my house (Flat Roof). We are looking to put PV solar panels on the roof to lower our energy costs. The sales people for the solar wanted to just anchor the PV panels into the roof joists and seal the pentrations with sealant. I feel that is unacceptable and will void my roof warranty. I am trying to connect the roofer with the PV people. To get the proper flashing instalation.

I think the right solution is to build a curb with the proper flashing / counterflashing wrapping the EPDM up the curb. This would be similar to the way HVAC units are installed and flashed on commercial buildings. Has anyone here done this or have any pertinent advice?

We have a PV Solar System on our present house and absolutely love it. And we certainly plan to install a PV system on our new house under-construction.

First our installation does not apply as we have a pitched roof, asphalt shingles with the PV panels mounted parallel to the roof line, on an aluminum track system with about a 3-4" standoff between the shingles and the panels. The perimeter has a bird & rodent screen. No matter if flat to the roof line or with tilt-ups, the mounting systems have been wind tunnel tested.

The solar company inspected the roof from the top as a professional roofer would and from inside the attic for structural engineering purposes. They would not install a system unless our roof was adequate. Roof penetrations were a major concern of mine. They had an excellent system with four layers of protection, the last of which is self-sealing mounting base. Bottom line, leakage is virtually impossible.

How does this relate? Our solar company has an excellent system and program; guaranteed for the 20 year design life of the system. If anything goes wrong with it, they maintain it. We opted to lease the system because we had doubts that we were going to live in our house to the 7 year 2 month (in our case, on this house) break-even point, which turned out correct. But the system, the service and guarantee is the same either way, buy or lease. They know what they are doing, did it right and professionally. I think it all starts with the solar company.

Our system is monitored remotely by the solar company, and independently by the leasing company and our utility company.
One of the meters has its own cell phone number. Every 6 hours it does a system data down load to the leasing company.
Online we can see how each panel is performing, or has performed any minute at any given time since it was placed in service.

Chances are there are other flat roofs in California with a EPDM, Single Ply Membrane roof with a PV system, without problems. In the Denver area solar systems on flat commercial roofs are being installed at steady and what appears as a fast pace. Our solar company does commercial and residential business in AZ CA CO FL HI NJ OR TX WA. Send me a PM if you want a contact.

EDITED TO ADD:

After reading:
* Shawn's post concerning rates - reminded me of one key feature of our solar system contract. Our rates are locked for life; immune to future rate hikes.

* Shawn's post concerning wind. A system must be designed for the "normal, worst case". Meaning if weather systems gust to 80 mph every few years. I don't know about rotational storms; the solar system could leave with the structure.

* I just learned our solar company is getting out of the residential business. They will do commercial and government business only.
They are selling the residential business division to our leasing company. We really liked both companies. Everything was right and nothing wrong in any way. What that means going forward, I don't know at this point, but they will still be our first go-to choice on our new house.

[David Weaver]

Unfortunately, our lot is only 3500 SF, so putting it on the ground isn't an option.

Figured as much. Barnyard land for farmers who no longer raise animals is in plentiful supply here - electricity is cheaper (~15-16 cents a kw/hr), land is cheaper, sun is not as good. I'm sure that in general, mandalay shores residents aren't going to be looking to dump 1000 square feet of solar panels in what little open space there might be.

Somewhere in my pinhead, I'm envisioning a flexible (but damped) structure that's attached to something other than the roof. I doubt something like that exists.