Ideal height above roof to install, and angeling.

[GoingElectric]

The cooler the PV is (at least below 75 F), the better it works.
Is there an optimum height? I saw somewhere 9" high brackets.

Also, is there methods to use different height brackets to change the angle slightly?

[J.P.M.]

Since the ambient air temp. will influence the cell temp. and is usually known or assumed for design purposes, a better way to discuss other things besides air temp. that can affect cell temp. - to a 1st approximation - is in terms of the difference in temp. between the cells/panels/array and the immediately surrounding ambient air temp.

Bottom line: In a local environment that has a moderate wind regime - maybe a 1-3 m/sec. common wind vector magnitude - once the top of roof deck to bottom of panel clearance is more than ~ 10 - 15 cm., any decrease between average cell temp. and the ambient air temp. is pretty small.

That is most of the advantage of increased air movement under the array by increasing the array to roof clearance for the purpose of decreasing the cell temp. will be cease beyond about 15 cm. or so of roof to array clearance with most of that improvement seen in the 1st 10 cm. or so.

[GoingElectric]

Since the ambient air temp. will influence the cell temp. and is usually known or assumed for design purposes, a better way to discuss other things besides air temp. that can affect cell temp. - to a 1st approximation - is in terms of the difference in temp. between the cells/panels/array and the immediately surrounding ambient air temp.

Bottom line: In a local environment that has a moderate wind regime - maybe a 1-3 m/sec. common wind vector magnitude - once the top of roof deck to bottom of panel clearance is more than ~ 10 - 15 cm., any decrease between average cell temp. and the ambient air temp. is pretty small.

That is most of the advantage of increased air movement under the array by increasing the array to roof clearance for the purpose of decreasing the cell temp. will be cease beyond about 15 cm. or so of roof to array clearance with most of that improvement seen in the 1st 10 cm. or so.

So a minimum of 10cm (4 inches for non metric speaking people) to allow enough cooling airflow, with insignificant gain mounted more than 15cm (6 inch) above roof.

I have seen (at least with SnapNrack) "skirt" at bottom edge of lowest panel for cosmetic reasons (reduces view under panels), but that seems like it will reduce airflow.

[azdave]

If you allow too much space underneath, the critters are happy to set up home under your panels, gnaw on the cables and leave piles of nesting materials and guano that you will have to deal with. You could put up wire screens to block them but the cost to raise up the panels higher than normal plus the screen protection is far more cost than you'll gain back if the panels run cooler by a few degrees. If it was a good idea with a reasonable payback time period, we would all be doing our installs that way.

Some people also experiment with water cooling the panels. Sounds good on paper but not in reality. Far cheaper and simpler to just add another panel or two if you have the capacity.

[J.P.M.]

So a minimum of 10cm (4 inches for non metric speaking people) to allow enough cooling airflow, with insignificant gain mounted more than 15cm (6 inch) above roof.

I have seen (at least with SnapNrack) "skirt" at bottom edge of lowest panel for cosmetic reasons (reduces view under panels), but that seems like it will reduce airflow.

The only countries still on the old english customary system of units besides the U.S. are Myanmar and Liberia. The U.S. is in good company

To your other two points: Correct and correct.

Skirts are a bunch of cosmetic B.S. that only inhibit air movement and so increase average array to ambient air temp. and so reduce array performance. Also, and like all the B.S. add-ons car dealerships pile on to a vehicle, they add an inordinate amount to the bill for little benefit other than the performance penalty of an array for the new owner and the profit for the pockets of the installer.

[GoingElectric]

To your other two points: Correct and correct.

Skirts are a bunch of cosmetic B.S. that only inhibit air movement and so increase average array to ambient air temp. and so reduce array performance. Also, and like all the B.S. add-ons car dealerships pile on to a vehicle, they add an inordinate amount to the bill for little benefit other than the performance penalty of an array for the new owner and the profit for the pockets of the installer.

Add to that make it easier to for critter nests to be built.

Talked with SunRun last night, no surprise, 1 size fits all kit. I am going over every detail and option.
and getting other quotes.

[J.P.M.]

Add to that make it easier to for critter nests to be built.

Talked with SunRun last night, no surprise, 1 size fits all kit. I am going over every detail and option.
and getting other quotes.

Get more educated and think with your long term brain, not your short term wallet. If you go with SunRun, or a PPA or a lease from anyone, my condolences in advance.

[nerdralph]

You could put up wire screens to block them but the cost to raise up the panels higher than normal plus the screen protection is far more cost than you'll gain back if the panels run cooler by a few degrees.

The CEC requires rodent guard in many cases, and some AHJs require it for all roof-mounted installations.

https://www.nspower.ca/docs/default-source/pdf-to-upload/b-64-200-solar-photovoltaic-installations.pdf

[GoingElectric]

Get more educated and think with your long term brain, not your short term wallet. If you go with SunRun, or a PPA or a lease from anyone, my condolences in advance.

I seen and read enough to know PPA are worse than Zombies. (SunRun has Loan option)
I have already decided I need to know every detail, every part that will be used.

[J.P.M.]

I seen and read enough to know PPA are worse than Zombies.

Keep reading and you'll also come to know that SunRun is in the same league.