New System in San Diego need input

[sensij]

In San Diego, one new complication to keep in mind is that as of Jan 1, Class A fire rating for the PV system must be met for permit approval. No panel by itself will meet this rating, but installed systems can. This has put a burden of testing on the racking manufacturer, and many of the common brands will offer conditional certificates of compliance that can be attached to a permit application. Most panels are rated either Type 1 or Type 2, with Type 1 providing more options for mounting configurations. LG panels are type 2, which means that if you want to install them in a method other than flush to a steep (>2:12) roof, the racking options are more limited.

I don't know how reverse tilt is addressed with respect to fire safety, but some research into the racking and panel combinations that are allowed is probably worthwhile if the design is being seriously considered.

Information on rack and panel ratings has been collected by CALSEIA here, and may be a good starting point if you want to understand this in more detail.

Also, see in this thread from last year more discussion of the development of the fire safety requirement.

[gboss]

They are going to install them at 90 degrees to the pitch of the roof. is that something that I should be concerned about?

thanks

[sensij]

They are going to install them at 90 degrees to the pitch of the roof. is that something that I should be concerned about?

thanks

If you are not the one doing the permit application, then no, you do not need to be concerned with it. However, if the installer isn't prepared for the new fire safety requirement and does not have a plan for dealing with it yet, you might expect some delays, equipment changes, or other redesigns when you get to the permitting stage. If you want to get in front of those possibilities, and your installer is open to your questions, it doesn't hurt to ask.

[J.P.M.]

They are going to install them at 90 degrees to the pitch of the roof. is that something that I should be concerned about?

thanks

I might be wrong but I don't believe the fire code speaks specifically to the plane of the panels not being parallel to the plane of the support structure, in this case, the roof. There may be some concern about impeding movement and clearance issues caused by tilted panels vs. panels parallel to the roof. I could even see some advantages to tilted panels as regards free space, particularly with respect to the 3' ridge clearance.

Fire safety and fire code issues are mostly separate from panel orientation angles and support /structural considerations with respect to what are called external loading design considerations, those loads being active - in the case of solar equipment loads caused by wind or seismic induced loads on the panels, structural supports and the roof and its components, or dead - those caused by equipment, snow, sometimes rain, and misc. stuff that doesn't usually move. Sometimes there are cyclic loads caused by vibration from rotating machinery.

Everything that can affect an assembly in terms of loading must be must be checked, and designed for or considered, including temporary loadings induced by construction activities such as people loads or such things as temporary roof tile stacking locations and limits. Those things are commonly ignored and one example of why engineers employ factors of safety in design work.

[sensij]

I might be wrong but I don't believe the fire code speaks specifically to the plane of the panels not being parallel to the plane of the support structure, in this case, the roof. There may be some concern about impeding movement and clearance issues caused by tilted panels vs. panels parallel to the roof. I could even see some advantages to tilted panels as regards free space, particularly with respect to the 3' ridge clearance.

No, fire code does not speak specifically to the panel orientation. It simply requires that the installed PV system achieve a Class A rating, if the structure on which it is installed is required to be Class A. The complicating factor is that a Class A rating is more easily obtained for steep roof flush mount systems than it is for low slope or tilt mount systems.

For example, the cert provided by IronRidge states the following:

Fire Class Resistance Rating:
-
Class A for Steep Slope Flush-Mount (symmetrical) Applications when using Type 1 and Type 2, Listed Photovoltaic Module
-
Class A for Low Slope Flush-Mount and Tilt-Mount (symmetrical and asymmetrical) Applications when using Type 1, Listed Photovoltaic Module.

During UL (or equivalent) testing, solar panels will receive a Type fire performance classification. Canadian Solar panels, for instance, are Type 1, and can therefore be used with IronRidge in a low slope application. LG panels are Type 2, and based on this cert, can be used with IronRidge only in a steep slope flush mount system.

Every racking supplier should be able to offer a cert that states under what conditions and with what types of panels the Class A rating can be obtained. CALSEIA has a nice equipment summary here, and more detailed discussion of the regulations here.

[J.P.M.]

Guess I got some homework to do.

[gboss]

Warranty

Ready to sign the contract but can anybody give advice on this warranty?

I asked for 10 year money back kWh production guarantee and this is what written in the contract:

"If notified by the customer-for any continuous twenty-four (24) month period during the Guarantee Period, the Actual Output is more than the 15% less than the kWh production mentioned in section Xll Limited Warranties for the same twenty-four (24) months we shall send you a refund check to cover the difference between the Actual kWh and 85% of estimated kWh shown on your proposal at a rate of .16 per kWh. this refund is limited to to any given twenty-four month period."

Any thoughts or advice on this??

Thanks for all the help

What a great forum for Solar

[J.P.M.]

Ready to sign the contract but can anybody give advice on this warranty?

I asked for 10 year money back kWh production guarantee and this is what written in the contract:

"If notified by the customer-for any continuous twenty-four (24) month period during the Guarantee Period, the Actual Output is more than the 15% less than the kWh production mentioned in section Xll Limited Warranties for the same twenty-four (24) months we shall send you a refund check to cover the difference between the Actual kWh and 85% of estimated kWh shown on your proposal at a rate of .16 per kWh. this refund is limited to to any given twenty-four month period."

Any thoughts or advice on this??

Thanks for all the help

What a great forum for Solar

Performance warranties are mostly a marketing tool for the vendors. Read the fine print about kWh production mentioned in section XII Limited Warranties. If your performance warranty works like most I've seen, I bet you'll find that number is already something like 10% lower than any reasonable estimate from something like PVWatts, which estimate BTW, if done by the vendor, is additionally and probably pretty conservative to begin with.

Also, more fine print (maybe): each year's surplus over their conservative estimate (which, because the estimate is so conservative, will likely be a pretty healthy surplus) will go into your account with any surplus in that account being used to offset any (unlikely) shortfall in output, further increasing the probability that a warranty claim will go nowhere.

Bottom line: most every performance warranty I've seen is useless, except as a marketing tool. The game is heavily rigged in favor of the vendor. You won't win. The performance bars before any warranty claims are paid are so low you'll be lucky you don't trip over them.

IMO only, performance warranties are another example of the solar business taking advantage of customer's solar ignorance. At best, they're useless. usually, they're little better than a dirty, cynical scheme.

Caveat Emptor. Read, REALLY read ALL the fine print and all the references in the fine print and take time to understand what it's all saying, while looking at what you read from the vendor's perspective.

Somewhat off topic but, Add: Notice that the customer is responsible for notifying the vendor. This is somewhat at difference to all the claims I've read from posters about vendors claims of monitoring performance and notifying customers of any production problems. I'm just sayin'.

[gboss]

roof leaks with Reverse Tilt panels

One company is implying that its not if - but when- the roof will leak because of the sail effect of solar panels on a reverse tilt array.The wind will slightly rock the panels and the rack and this constant rocking will cause leaks eventually, and since your panels are warrantied for 25 years you will fight this issue multiple times over the 25 year period.
Sales ploy or fact???
If this is true why are there so many of them around? I want to make sure before I have this installed that this is not a normal occurrence in a moderate to light windy area. They have a 10 year warranty on roof leaks but i am going to ask that to be increased to the life of the panels.

Thoughts or advice?

Love this place!!!!

[J.P.M.]

One company is implying that its not if - but when- the roof will leak because of the sail effect of solar panels on a reverse tilt array.The wind will slightly rock the panels and the rack and this constant rocking will cause leaks eventually, and since your panels are warrantied for 25 years you will fight this issue multiple times over the 25 year period.
Sales ploy or fact???
If this is true why are there so many of them around? I want to make sure before I have this installed that this is not a normal occurrence in a moderate to light windy area. They have a 10 year warranty on roof leaks but i am going to ask that to be increased to the life of the panels.

Thoughts or advice?

Love this place!!!!

I agree that roofs will leak. One of the goals of good design is to help ensure a high probability of leak tightness for the planned life of the system. One part of good design is consideration of all possible/likely external loadings on a structure/system and the impact and consequences of such loadings. That's what we're talking about here.

IMO, most of what you were told is sales B.S. What the peddler may be referring to is sometimes called cyclic loading, but probably more accurately described as variable stress caused by alternating loadings of a somewhat random but recurring and more or less frequent nature. That type of loading, regardless of name, is reasonably well understood. Any knowledgeable designer is aware of such conditions and will consider it as appropriate in any thorough design. That's part of what a good design entails. I'd hazard a guess and say whoever told you that stuff is repeating what they heard, and has little if any idea what is required or why.

Most folks have a common sense awareness of how the wind, or for this conversation wind variation or gustiness, can make things wobbly sooner or later. You think competent structural designers are not aware of the fact that the wind varies ?

Check out ASCE 7-05/10 for some of the design considerations.

[gboss]

I agree that roofs will leak. One of the goals of good design is to help ensure a high probability of leak tightness for the planned life of the system. One part of good design is consideration of all possible/likely external loadings on a structure/system and the impact and consequences of such loadings. That's what we're talking about here.

IMO, most of what you were told is sales B.S. What the peddler may be referring to is sometimes called cyclic loading, but probably more accurately described as variable stress caused by alternating loadings of a somewhat random but recurring and more or less frequent nature. That type of loading, regardless of name, is reasonably well understood. Any knowledgeable designer is aware of such conditions and will consider it as appropriate in any thorough design. That's part of what a good design entails. I'd hazard a guess and say whoever told you that stuff is repeating what they heard, and has little if any idea what is required or why.

Most folks have a common sense awareness of how the wind, or for this conversation wind variation or gustiness, can make things wobbly sooner or later. You think competent structural designers are not aware of the fact that the wind varies ?

Check out ASCE 7-05/10 for some of the design considerations.

Thanks again JPM

Your wisdom has really been an asset in this process and I am thankful

[J.P.M.]

Thanks again JPM

Your wisdom has really been an asset in this process and I am thankful

You're welcome. Gather all opinions. Mine is but one of many and subject to being wrong or at least incomplete.

[sensij]

In the "other opinions" category, I've just read through the thread again and still do not understand the layout you are considering. It also isn't clear that the cost of tilting system you want to use will yield enough additional generation to be justified.

While it may be true that it is possible to design and install a reverse tilt that won't leak in the design life of the system, I believe that it is also true that if the amount of effort put into the design and install is constant, a flush mount system is less likely to leak in that same period. In other words, the tilted system should cost more to do it right, and if you are shopping on the low end of the market price range, the chances that someone will just tell you what you want to hear and then go do whatever they want increases.

Your best defense is education... find out what tilted system they plan to use, and what the proper installation of that system should be. If you want to assure a good outcome, your role in this does not end as soon as you sign the contract.

[J.P.M.]

After all the conversation about non flush (tilted) arrays, engineering design considerations and attachment systems, I may have allowed some inferences to creep in that I think tilted arrays are always superior to flush (parallel to roof) arrays. That would be contrary to my opinion(s) for the most part.

1.) Tilted arrays may well have some advantages in places where roofs are horizontal or in applications where reasonably decent roof orientations for flush mounting are not available.

2.) However, for many even halfway decent roof orientations, say +/- 30 deg. e-w of due south and a tilt greater than about 15-20 deg. up to about 45 deg. or so, the performance increment and thus bill reductions probably do not warrant tilting an array. A 5 to 10% penalty in annual solar performance per m^2 of panel area can probably be made up with an increase in panel area or load reduction much more easily and less expensively than a costly engineering effort that looks like an explosion in an erector set factory.

3.) Economics and aesthetics are both in play here. Engineering is not so much a factor (beyond a bill for services which is about system cost and thus economics) as tilted arrays are a solved problem design wise. Failures due to wind are mostly from lack of any design or systems not built to plan.

4.) I'd be much more concerned about a good roof to start with, and robust standoffs with particular attention to flashing systems that help ensure no leaks or other problems for the life of the system.

5.) A Solar electric system is a means to an end - a lower electric bill, resulting in saving money. A system that may harvest a small additional amount more power because of slightly more favorable orientation at the expense of inducing damage to a home, either physically through faster deterioration and increased maintenance, or because, rightly or wrongly it is perceived by some as an eyesore, is out of sync with the original bottom line : To save the most money for the chosen time period.

6.) If the goal is to save the most money in the most cost effective way, reduce your use. Reduce it enough and you'll also reduce the required system size, maybe even enough to not need a tilted array or the reduced footprint that Sunpower provides.

[gboss]

Signed the Contract

Let the games begin. We signed the contract. The price is 3.41 per kWh for 12.32 Kw size. Deposit back if system does not fit on roof as stated.

We could not get them to add a 20 year warranty for the roof but we gave it a try.

Will keep you posted and again thank all of you who helped