Roof penetration question

[bonbon]

If the number of panels is same (say 10) does it matter how many roof plane/surfaces are they are installed on?

Or is there a general guideline to focus them all together? I have a complex roof and I am trying to compare two quotes.
Here is an example of our roof:

https://i2.wp.com/www.roofingcalc.com/wp-content/uploads/2015/11/complex-roof-photo-render.jpg?ssl=1

One of them have the design using 3 roof planes/surfaces vs the other one is using 4 roof planes/surfaces.

Does that make any difference? The number of solar panels are the same in both cases. Would having it on more roof surfaces increases the number of roof penetrations or it does not matter because the number of solar panels is the same in both cases.

Both are reputable companies and have done a lot of work in my area. Both claim no roof leaks, etc. But I wanted opinion of some of you folks who understand this better. Any suggestions would be a great help.

[AzRoute66]

Way too many 'panels' in there. 10? 3? 4? same? different? Let's try again with consistent terminology. Maybe use solar modules, or roof surfaces, and for each roof surface be sure to include if it has a different compass orientation. Thanks a lot.

[max2k]

If the number of panels is same (say 10) does it matter how many roof panels are they are installed on? Or is there a general guideline to focus them all together? I have a complex roof and I am trying to compare two quotes. One of them have the design using 3 roof panels vs the other one is using 4 roof panels. Does that make any difference? The number of panels is the same in both cases. Would having it on more roof panels increases the number of roof penetrations or it does not matter because the number of panels is the same in both cases.

Both are reputable companies and have done a lot of work in my area. Both claim no roof leaks, etc. But I wanted opinion of some of you folks who understand this better. Any suggestions would be a great help.

did you mean 'roof planes' - sides of the roof solar panels are installed on or literally panels of the roofing material?

[sdold]

There's no technical advantage to having all of the panels grouped together, but it simplifies the wiring and mounting rail layout and may slightly reduce power losses in the wiring. There's no "focusing" or "phasing" involved.

[ButchDeal]

[QUOTE=AzRoute66;n361571]Let's try again with consistent terminology. Maybe use solar modules, .../QUOTE]

you're learning.

[ButchDeal]

If the number of panels is same (say 10) does it matter how many roof panels are they are installed on? Or is there a general guideline to focus them all together? I have a complex roof and I am trying to compare two quotes. One of them have the design using 3 roof panels vs the other one is using 4 roof panels. Does that make any difference? The number of panels is the same in both cases. Would having it on more roof panels increases the number of roof penetrations or it does not matter because the number of panels is the same in both cases.

Both are reputable companies and have done a lot of work in my area. Both claim no roof leaks, etc. But I wanted opinion of some of you folks who understand this better. Any suggestions would be a great help.

You are using the word panel for two different meanings.

What inverter did they use? If SolarEdge or enphase it doesn't make much difference. Though there are likely other reasons for the differences in number of roof facets used.

[peakbagger]

If you have multiple roof surfaces you most likely will be buying several more mounting feet with associated flashings compared to single roof mount. These are fairly expensive compared to buying a few feet of extra rail. Installing them correctly also eat up more labor as they need to be screwed into the underlying framing. Keep in mind ever hole in the roof is potential leak although if the right flashing system is used its very unlikely.

If you are splitting them up definitely consider microinverters as a string inverter MPPT circuit needs panels with uniform lighting and different roof exposures will give different panel outputs which confuse the MPPT. If it was bigger array and you could set up multiple strings there are string inverters with dual MPPT but expect with yours microinverters are the way to go even though they cost more.

[bonbon]

If you have multiple roof surfaces you most likely will be buying several more mounting feet with associated flashings compared to single roof mount. These are fairly expensive compared to buying a few feet of extra rail. Installing them correctly also eat up more labor as they need to be screwed into the underlying framing. Keep in mind ever hole in the roof is potential leak although if the right flashing system is used its very unlikely.

If you are splitting them up definitely consider microinverters as a string inverter MPPT circuit needs panels with uniform lighting and different roof exposures will give different panel outputs which confuse the MPPT. If it was bigger array and you could set up multiple strings there are string inverters with dual MPPT but expect with yours microinverters are the way to go even though they cost more.

Thank you all for your responses. I have since updated my Original post to correct terminology. I am South Carolina and this is a fairly new home built by a builder (there are tons of them these days). So we are concerned about the number of penetrations they are going to make in the roof surfaces. Both are very reputed installers in the area and have given us assurances that they use industry standard equipment for install. They are using Solaredge inverter. But I am not sure what flashing, etc. they use for covering roof penetrations.

Just as you have said, every hole they put in, has the potential to leak so I was not sure if I should force them to stick to one or two surfaces. So that if there is ever a leak it would be in in one area. Vs let them spread it out to 3-4 roof surfaces. Would that help in anyway or is it just in my head? their argument is that since the number of solar panels is the same, the penetrations would also be the same. So it does not make any difference. Is that correct?

[ButchDeal]

They are using Solaredge inverter. But I am not sure what flashing, etc. they use for covering roof penetrations.

Ask them for the racking and flashing models they are using. We use Ironridge and the FlashFoot II primarily which is a solid product.

https://www.youtube.com/watch?v=-qN5dwEumCM

Since they are using SolarEdge they could have every single PV module facing a different direction if need be (to the extreme ) and electrically it will provide max power available.

[bonbon]

Ask them for the racking and flashing models they are using. We use Ironridge and the FlashFoot II primarily which is a solid product.

https://www.youtube.com/watch?v=-qN5dwEumCM

Since they are using SolarEdge they could have every single PV module facing a different direction if need be (to the extreme ) and electrically it will provide max power available.

I just called one of them and they use the same as you (Ironridge and the FlashFoot II). But it would be great if you could answer my question.

My question is back to penetrations. Should we try to force them to put all the panels on the single roof surface? Or it does not matter and as long as they use correct flashing/equipment, penetrations don't matter. Because someone above said if there is a penetration, there is potential for leak.

[AzRoute66]

[...] Should we try to force them to put all the panels on the single roof surface?

In my opinion, you should not try to 'force' them into any particular solution, unless you are 100% convinced that you have the right of it. That does not appear to be the situation in this case. Most installers are not out to do something dumb, they are very vested in making sure that they do things right, and really have no reason at all to lie to you. I can hear the cynics' fingers hovering over their keyboards, but if you are dealing with reputable firms see what they propose, and consider it well, before you say, "My way is the only right way."

I have my system planned down to the number and type of lag bolts to use on the roof, but when I go to get quotes I am not going to show them mine until I see theirs. They just might come up with something I had unjustly discounted or never considered.

I realize that I also 'did not answer your question' per se, Let us see the proposal, in detail, and we can perhaps answer some risk/reward questions. Until then, do not worry about the extra penetrations. Better?

Edit: I skipped over the picture of the roof when I was trying to sort out all of the uses of 'panel' in your original post. I just now looked at it. Magnificent. I can see where multiple surfaces are being proposed, I would be worried if the installer didn't propose it that way. I think your time would be better spent getting your installer to photoshop what the finished product is going to look like. I think it might be easy to create something you really don't care to look at.

[ButchDeal]

I just called one of them and they use the same as you (Ironridge and the FlashFoot II). But it would be great if you could answer my question.

My question is back to penetrations. Should we try to force them to put all the panels on the single roof surface? Or it does not matter and as long as they use correct flashing/equipment, penetrations don't matter. Because someone above said if there is a penetration, there is potential for leak.

I could not say why they put them on different roof surfaces. Were they leaving the required setbacks for fire code? avoiding shadows?
The difference in the number of penetrations is likely minimal for using two panels (surfaces) rather than a single panel array.

With a penetration there is a potential for leak however minor, however what you might not know is that your roof has thousands of penetrations now with staples or nails.
These solar flashfoot II penetrations when done correctly are less likely to leak than the nails holding your roof on in the first place.

Clearly you are not sure though why they did the design the way that they did it. Some things you can do about that are to get other quotes and see how they are done, and ask the installer so that you know. If the roof facets are facing different directions it could be that they are trying to effect time of use billing or something of that nature, or as I mentioned before the fire code setbacks or shadows are making the other roof surfaces more advantageous.

[J.P.M.]

I just called one of them and they use the same as you (Ironridge and the FlashFoot II). But it would be great if you could answer my question.

My question is back to penetrations. Should we try to force them to put all the panels on the single roof surface? Or it does not matter and as long as they use correct flashing/equipment, penetrations don't matter. Because someone above said if there is a penetration, there is potential for leak.

Probably not. First of all, they know more than you about the subject. Second, if they have any professional integrity, you may be able to work with them, but at some point close to absurdity, they'll say no. Third, if they do as you mandate, they'll likely disavow any liability. Fourth, if any of what you mandate is not code compliant, the AHJ will likely flag/red tag it.

Roof penetrations will and do leak if not done in a professional and time proven way. From what I've seen, there are more than a few roofs with PV on them that are ticking bombs for leaks.

Believe it or not, as you choose.