Free Power From the Sun

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weressl said:
Ballasted solutions to/for sloped, asphalt-shingle in a wind rated application?
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Well, there is =that=. But most of the larger commercial installations I've seen are very boring and very flat, and for resi, the penetrations are flashed and sealed and will last longer than the rest of the roof, without leaking. I mean, you've got a hole in the roof that is protected from driving wind and rain by a large object. Unless the penetrations are done poorly, I'm not seeing that as a problem.
 
jaggedben said:
Maybe because they're not keeping up to date? :D Seriously. Look at the figures on page 11 here: http://www.seia.org/galleries/pdf/SMI-Q1-2011-ES.pdf

But with that said, your overall point is well taken, $4.5 per watt installed cost would seem to be about the lower boundary for residential, not the average, which SEIA pegs at $6.41 at the end of last year (and they are not an uninterested source, I realize).
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Remember that SEIA gave average price, which includes "all the bells and whistles" systems in with the "bare bones" and "price optimized" ones. In terms of dollars-per-watt, there are premium panel vendors who make very nice, very efficient, and very expensive monocrystalline panels, and people who buy very expensive, very nice, and not all that much better inverters.

It's possible to design for that lower price point by staying away from the 15+% efficiency top-dollar monos, as well as the SMA and other big money string inverters.
 
tallgirl said:
Well, there is =that=. But most of the larger commercial installations I've seen are very boring and very flat, and for resi, the penetrations are flashed and sealed and will last longer than the rest of the roof, without leaking. I mean, you've got a hole in the roof that is protected from driving wind and rain by a large object. Unless the penetrations are done poorly, I'm not seeing that as a problem.
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The overwhelming majority of roof surfaces in the US are private residences with asphalt shingles. Your statement on roof penetrations - flat or otherwise - does not jive with real life.
 
weressl said:
The overwhelming majority of roof surfaces in the US are private residences with asphalt shingles. Your statement on roof penetrations - flat or otherwise - does not jive with real life.
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That has been my experience. Any roof leak I have ever seen on a roof that is in otherwise reasonable condition starts at some penetration. I have seen many asphalt shingles that are in need of replacing but with no penetrations anyplace have no leaking problems. There are ice dam problems in northern states but you guys were not even talking about roofs in those areas.
 
weressl said:
The overwhelming majority of roof surfaces in the US are private residences with asphalt shingles. Your statement on roof penetrations - flat or otherwise - does not jive with real life.
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The installers I know are meticulous about penetrations on residential roofs. Typically the penetration is made, adhesive sealant put down, flashing, the penetration is filled with adhesive sealant, the lag screw is inserted through the footing, flashing, etc. and tightened into the rafter through the decking, then covered in adhesive sealant.

I have more concerns about removing the footings than leaks.
 
tallgirl said:
The installers I know are meticulous about penetrations on residential roofs. Typically the penetration is made, adhesive sealant put down, flashing, the penetration is filled with adhesive sealant, the lag screw is inserted through the footing, flashing, etc. and tightened into the rafter through the decking, then covered in adhesive sealant.

I have more concerns about removing the footings than leaks.
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In theory that is how it is supposed to be done. In real life they will leak. Anything that relies on field installation is suspect of quality control and roofers are one of the poorest in that area. Just look at who is installing asphalt shingles! Hardly any of them speak English, nevermind reading English instructions or Spanish for that matter. If the 'solar guys" install the standoffs, what kind of roofing experience do they have? Caulks have a stated life, but hardly any of them will last that long under field conditions - dirt, contamination, temperature and moisture problems during installation. Then there is the cheapest bid syndrome. If the guy is lump sum he will use the cheapest labor and material, they not exactly looking for return customers. If the guy is performing the work as the low bidder, he not only will use the above but perform shortcuts that will result in poor life expectancy. I mean do you hear roofers and quality control mentioned, EVER, in the same sentence?

Yeah, keep Austin weird. (Reality is for others.....):D No personal offense to you Julie, seriously. Been there done that, drank the Kool-Aid.
 
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I'm on a pretty large number of solar-related mailing lists, forums, etc. and I'm not hearing a lot of "ZOMG! My penetrations leak!" stories.

FWIW, the only penetrations I've ever heard of leaking were one client and the installer was on his third job. He's since gone out of business, so far as I can tell.
 
I was on call to fix roof leaks for a week during our worst week of rain last winter here in Northern California. My company has hundreds (thousands?) of systems installed under warranty in my shop's area.

I didn't have to respond to a call.

weressl has some points, certainly, but ultimately it just comes down to another cost that PV has to keep under control in order to try to compete with utility electricity. As of yet I don't see any signs that it will be a very significant cost among all the others.
 
tallgirl said:
I'm on a pretty large number of solar-related mailing lists, forums, etc. and I'm not hearing a lot of "ZOMG! My penetrations leak!" stories.

FWIW, the only penetrations I've ever heard of leaking were one client and the installer was on his third job. He's since gone out of business, so far as I can tell.
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How old are the installations? That can make a big difference of the likelihood of leaking.
 
kwired said:
How old are the installations? That can make a big difference of the likelihood of leaking.
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I know people who've had solar on their homes going back to the 1970's. I've not heard "you need to redo the sealant every 10 / 15 / 20 years" from anyone. In fact, other than people asking the question, this is the first I've heard that solar installations on shingle roofs are a significant / realistic leak problem.

Now, maybe in ice and snow country, but I'm on boards with people who live above the arctic circle, so ...
 
I'll just keep repeating to myself, "That leak in my roof next to the penetration in my roof is just a coincidence. Hopefully, that will make the leak go away! ;)
 
tallgirl said:
I know people who've had solar on their homes going back to the 1970's. I've not heard "you need to redo the sealant every 10 / 15 / 20 years" from anyone. In fact, other than people asking the question, this is the first I've heard that solar installations on shingle roofs are a significant / realistic leak problem.

Now, maybe in ice and snow country, but I'm on boards with people who live above the arctic circle, so ...
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Talk to ANY roofer about roof penetrations. Make sure you talk to them off-the-record.

Let me take another tack, maybe that lights up some bulbs up there. Do you know the failure rate of MV splices, compared to the unspliced lenghts? Do you know why there is a difference/ What the fundamental reason is?
 
tallgirl said:
I know people who've had solar on their homes going back to the 1970's. I've not heard "you need to redo the sealant every 10 / 15 / 20 years" from anyone. In fact, other than people asking the question, this is the first I've heard that solar installations on shingle roofs are a significant / realistic leak problem.

Now, maybe in ice and snow country, but I'm on boards with people who live above the arctic circle, so ...
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I have no experience with solar power. I have seen my fair share of leaking penetrations from plumbing, HVAC, electric service masts, gas appliance outlet vents, or anything else that penetrates a roof and pretty much any type of roof.

In snow and ice country things are worse when there is snow or ice on the roof as it dams up water and allows it to penetrate small cracks that it may not otherwise enter during rain shower in warmer conditions.
 
weressl said:
If you know the answer to the question then the answer is obvious. If not it is easy to research and is educational.:D
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There is nothing obvious about the relevance of a type of hardware that, to my knowledge, is not used in PV installations. That's what this thread is about, right?
 
I don't have time to research, but I'm betting the gist of what he's getting at is that the more you complicate any machine or system, the more opportunity for failure. An unbroken conductor is less likely to fail than a broken conductor, due to the added parts.

You add holes to a roof, regardless of precaution, you have added the weakest link to that roof. It's that simple.
 
George Stolz said:
I don't have time to research, but I'm betting the gist of what he's getting at is that the more you complicate any machine or system, the more opportunity for failure. An unbroken conductor is less likely to fail than a broken conductor, due to the added parts.

You add holes to a roof, regardless of precaution, you have added the weakest link to that roof. It's that simple.
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Yes.


One more post will be 100.
 
Okay, here's 100. :)

George Stolz said:
I don't have time to research, but I'm betting the gist of what he's getting at is that the more you complicate any machine or system, the more opportunity for failure.
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I agree about complications, but it seemed to me that he was referring specifically to something about medium voltage (MV). I was curious about that, but since solar systems don't involve medium voltage, I was at a loss to understand what his point was.
 
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