Question on Flush Roof Mount in Hurricane Prone Region

System

When mounting solar panels flush (for example with Unirac or Iron Ridge) to a roof in a hurricane prone area (e.g. southeast Texas), what is the minimum suggested distance one should keep between the edge of the panel and the gutter? Eave? Peak?

I presume that if the panels are mounted too close to the roof's edges, there is a greater possibility that the wind will get under the panels and cause lift than if they are set back some inches.

Does anyone know what the recommended distances are?

Thanks.

niel

Re: Question on Flush Roof Mount in Hurricane Prone Region

i don't think it matters that much as it could lift your roof too so why worry about it? you should allow an air space for the pvs to cool some with airflow underneath and generally 6 inches or more is good for that. if you want to worry about something then worry about the debris being blown into the pvs.

newenergy

Re: Question on Flush Roof Mount in Hurricane Prone Region

When you do the wind load calcs the setback do matter. Unirac has some very detailed info on the wind load calcs in their mounting instructions. It's not super complicated, but it is kind of a lot to go through.

At the ProSolar office they have a picture of one of their arrays from New Orleans and all the shingles blew off the roof in Katrina except the ones under the array - and the array was still there.

sub3marathonman

Re: Question on Flush Roof Mount in Hurricane Prone Region

Conergy makes panel mounts, and I thought they were very good. There is a "SunTop Sizing Tool" you can use to figure out what you need, and in the sizing tool it tells about the roof edge.

"Roof edges are defined as the dimension a in Figure 6-3 below. The dimension a is quantified as 10% of the least horizontal dimension of the building or 0.4h, whichever is smaller, but not less than either 4% of the least horizontal dimension of the building or 3 ft (0.9m). Corner areas are those areas where roof edge areas overlap. Roof edge areas can also include the areas around large chimneys, parapets, or other large structures or equipment that protrude above the roof. If your arrays will be near any such large structures or equipment, please contact a professional engineer for help in determining roof edge areas."

It was my understanding that the edge is subjected to additional wind loads, but I also had to have a PE check everything over too and he figured out that the panel mountings were fine.