Reverse tilt kits?

[DanKegel]

Yeah, they're common in Australia, and there are installers in California who have pictures of 'em ( e.g. http://www.raycoenergy.com/projects_...lt-solar.shtml ).

That's exactly what I'm trying to tap into -- what are the existing designs? It's hard to scare up any detailed documentation of how reverse tilt mounts have been done in the US.

[J.P.M.]

Neither of them seem to have experience with reverse tilts, which isn't surprising. I tend to overload people with questions; I'm trying to learn here so I waste less of their time. And of course I try to piece together what I can from manuals and tutorials on the internet so I waste peoples' time less here.

Not surprising to me in So.CA. However, many such systems do exist. I can think if 2 off the top of my head that I drive by on a daily/weekly basis. If you go to northern latitudes, they are quite common. I suspect a decent structural P.E. could come up with or check an existing design. Solar array structural design ain't rocket science, and what you have is not that big.

I'd offer a guess, but not an opinion that your biggest hurdle, after the strut issue, will be getting the roof and the attachments to it safe, fit for purpose and correct.

[DanKegel]

Neither of them seem to have experience with reverse tilts, which isn't surprising. I tend to overload people with questions; I'm trying to learn here so I waste less of their time. And of course I try to piece together what I can from manuals and tutorials on the internet so I waste peoples' time less here.

[J.P.M.]

Yup. I'm working with the P.E. the solar installer hired.

I understand that from prior your posts. I appreciate the value of asking questions, and don't want to sound anti-inquisitive, but if you're already working with a P.E., why ask questions here ? Can't you ask the P.E rather than seek unvetted opinion from folks with no skin in the game ?

If you don't like what you have or what you're getting, maybe you should ask for your money back, or hire your own P.E.

[DanKegel]

And others as a suggestion for places for ideas only. Not a recommendation as to suitability. My suggestion to consult and seriously consider the opinions of a P.E. qualified to practice in that area of engineering is still good.

Yup. I'm working with the P.E. the solar installer hired.

[J.P.M.]

In https://www.solarpaneltalk.com/forum...655#post300655
JPM suggested looking at IronRidge's adjustable tilt leg.

And others as a suggestion for places for ideas only. Not a recommendation as to suitability. My suggestion to consult and seriously consider the opinions of a P.E. qualified to practice in that area of engineering is still good.

[DanKegel]

In https://www.solarpaneltalk.com/forum...655#post300655
JPM suggested looking at IronRidge's adjustable tilt leg.

http://files.ironridge.com/roofmounting%2FIronRidge_RM_EngineeringDesignGuide.pdf

IronRidge's install manual

http://files.ironridge.com/roofmounting%2FIronRidge_Standard_Rail_Design_Manual.pdf

doesn't quite say how to attach the tilt legs to the roof.
They do sell "tilt leg standoffs", and the video describing how to use the tilt mounts,

https://www.youtube.com/watch?v=_PvCi-BfygY

shows them being used with standoffs... but the tilt leg standoffs are "for use with 1 to 10 degree tilts only".
What do you use under the U-feet if you don't use standoffs?

Can someone describe how they've mounted IronRidge tilt legs to a sloped roof?

(I ask because my installer has proposed mounting them on
FastJack standoffs, and the PE hasn't commented yet. The FastJack standoffs
use only a single lag bolt, and to my untrained eyes don't seem intended for this application.
The PE has previously emphasized that two bolts are needed.)

[DanKegel]

http://solpowerpeople.com/solar-pv-racking-with-unirac/ has a video by a Unirac support engineer.
About half an hour in, it discusses some of the problems with reverse tilt mounts.

[inetdog]

Wind loading is a real can of worms. The ASTM standards are definitely not done with solar panels in mind. My engineer has software to figure the wind loading and it comes up with stupidly high numbers for the uplift that panels could see (over 150lb per tilted panel on an exposed flat roof). Reverse tilted panels could be way worse. The mounting manufacturers are not going to help you much. Probably going to need to find a local PE to get a building departments approval.

Just off the top of my head I do not find that stupidly high. At least not by a full order of magnitude anyway. Think storm winds not ordinary breezes. And then think of the loading per square foot of an airplane wing.

[Naptown]

Wow. What LEED version was that building graded against?

LEED V2 (2004) was only 52 or more points to meet Platinum requirements. For LEED 2009 and now V4 2015 you need to score 80 or more points to get Platinum.

Must be a very energy efficient building.

Very first LEED Platinum building in U.S.

[SunEagle]

We have done a few the engineering is a big factor. Most recent was on a waterfront building on the Chesapeake bay. Exposure category 4 and a bit above 100KW. Can be done but will require a thorough engineering evaluation. In that case roof slope was 10 degrees and panel tilt was 10 degrees. Making the first leed platinum building even more platinum.

Wow. What LEED version was that building graded against?

LEED V2 (2004) was only 52 or more points to meet Platinum requirements. For LEED 2009 and now V4 2015 you need to score 80 or more points to get Platinum.

Must be a very energy efficient building.

[DanKegel]

Installing solar panels on a roof is deceptively simple. For flush mounts, the kinks have long been worked out. Reverse tilt, not so much, and fools rush in where angels fear to tread.

Australia seems ahead of the US in this regard, judging by the fact that the only vendor willing to specify how to use their mounts for reverse tilt is in Australia.

Has there been an article about the issue in any solar industry publication?

http://www.solarabcs.org/about/publi...orts/wind-load does not recommend mounting panels at a tilt relative to the roof, but it quite doesn't come out and say "we do not recommend reverse tilt mounts". (I guess it's trying to help people follow good practices, not dissuade them from following unproven practices.)

http://www.nabcep.org/wp-content/uploads/2013/08/NABCEP-PV-Guide-7-16-13-W.pdf

says:

Before recommending or deciding on any PV array mounting system, verify with
the mounting system supplier that the hardware is appropriate for the given ap-
plication. Also, it is generally not advisable to try to fabricate or copy a mounting
system design for smaller projects. This usually costs much more than purchasing a
pre-engineered system, and may not meet the structural or environmental require-
ments of the application. PV array mounting structures also must be electrically
connected to the equipment grounding system, and special bonding jumpers and
connectors are available to maintain electrical continuity across separate structural
components. Oftentimes, local jurisdictions require engineering documentation to
certify the structural integrity of the mounting system and attachments.

Which brings us back to the question: do any mounting system suppliers in the US
support reverse tilt mount applications?

[J.P.M.]

IronRidge also does not support them. "The reverse tilt applications are often done improperly, and are no longer support by IronRidge. Any failures of reverse tilt installation are not going to be covered by our warranty. This will also hold true with our new tilt legs."

Which may be saying something about the preliminary or other engineering and site planning/prep among other things. The engineering may or may not be complicated, but in any case, necessary, but often missing, and IMO only, often out of willful ignorance. Without doing their thinking for them, Perhaps that's part of what IronRidge is saying between the lines.

Part of the reason behind IronRidge's decision may be a consequence of something I've noticed on solar applications and often in R.E. circles. That is, the necessary engineering is often misunderstood, ignored, or not known to exist.

While most certainly not painting all R.E. people with the same brush, IMO, it is often easier to find ignorance, poor attitudes and lack of professionalism when dealing with R.E. outfits than say, for example, those found in a refinery or a nuke.

I may not necessarily like their products or agree with all their corporate opinions about what's best for the planet, but after an engineering career in/around a lot of conventional energy generation, and a foot and one eyeball in my first and technical passion - R.E - for longer, IMO only, unless I determine otherwise, and sorry to say it, when it comes to professionalism, safety and the quality of the engineering, I'll trust the conventional end of the energy business for those things until I see a change. Some of the ignorance and bad attitudes that are easier to find on a solar job site would not be tolerated if found in, say, a refinery or a large nuke.

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

[Amy@altE]

IronRidge also does not support them. "The reverse tilt applications are often done improperly, and are no longer support by IronRidge. Any failures of reverse tilt installation are not going to be covered by our warranty. This will also hold true with our new tilt legs."

[Naptown]

We have done a few the engineering is a big factor. Most recent was on a waterfront building on the Chesapeake bay. Exposure category 4 and a bit above 100KW. Can be done but will require a thorough engineering evaluation. In that case roof slope was 10 degrees and panel tilt was 10 degrees. Making the first leed platinum building even more platinum.