Is any vertical spacing between panel rows required?

[corbin]

Hi! I'm doing a grid-tied install on the standing seam metal roof on my shop. I'm using REC410 panels, installed "portrait". There will be 3/8" spacing between the panels for the clamps. Should I have spacing between the two rows? I don't think it is required, and I'd prefer no spacing to allow snow to slip off more easily.

 

[pollenface]

Just make it practical for you!

Spacing allows for heat expansion, for what it's worth

 

[corbin]

Just make it practical for you!

Spacing allows for heat expansion, for what it's worth

Cool - practical for me is zero spacing. REC's install guide doesn't mention any requirement for heat expansion -- should I be concerned?

They do have requirements for the space distance under the panels to the roof, which I think is for cooling purposes.

 

[Steve_S]

There are several "Gaskets" made from hi-temp neoprene-silicone that go between the panels to seal/close the gaps while allowing for any small movement. These can be used to make a waterproof array and due to the silicone, no moisture (rain/snow/ice) will stick allowing it to easily slide off the panels. Also this makes for a really nice finished look. A few years ago a coupe of companies tried & failed because the materials they used were not up to it BUT that's over and the new siliconized stuff is incredible AND it's not that expensive.

Lessons Learned shared by others, It is easier to use these if panels are on a Rail Mounted system, lay in 1st panel & tighten down, then with next panel still "loose" install the gasket and press next panel into place & tighten down. Don't bother trying to squeeze/stuff the gasket in after... you'll pull hair & freak if you damage something. Many of these gaskets now also have + & L pieces to really finish them nicely. Believe it or not, they can even come in different colours if you have an artistic decorative bent.

Note: There are a few that require adhesive (typically silicone) - DON'T ! The better option are the ones that press in and cover the whole width of the aluminum sie and texted a little below, These have 3 or 4 little wings with a larger one for underneath while the top os gently rounded low profile. Also NEVER Forget that Panels do require airflow behind them, so so not restrict that.

There are a few good vids on YT about these.

Hope it helps, Good Luck.

 

[OzSolar]

Spacing is required on all 4 sides of the panel or you risk breaking them during the expansion with temp changes.

I saw a real world example of this while helping a buddy install an IronRidge ground mount. We were taking panels out of pallet that weren't in direct sunlight and mounting them in direct sunlight. My buddies nephew didn't think to leave a gap on the last panel we installed since we were getting ready to take break before installing more panels. After about 15 minutes we heard it "pop" and found a shattered module with no spacing. YMMV

I am not familiar with the gaskets that Steve_s mentioned but they sound interesting.

 

[corbin]

There are several "Gaskets" made from hi-temp neoprene-silicone that go between the panels to seal/close the gaps while allowing for any small movement. These can be used to make a waterproof array and due to the silicone, no moisture (rain/snow/ice) will stick allowing it to easily slide off the panels. Also this makes for a really nice finished look. A few years ago a coupe of companies tried & failed because the materials they used were not up to it BUT that's over and the new siliconized stuff is incredible AND it's not that expensive.

Thanks Steve, I'll have to look up those products and see if I can get some before I install my panels; I'm pretty close to installing them, so I might just leave a gap. It also sounds like you are implicitly recommending a gap between them.

Edit: And I am using 3 rails per panel, mounted "portrait". We have a high snow load in my area, and the engineer went crazy with mounts.

 

[corbin]

>>Spacing is required on all 4 sides of the panel or you risk breaking them during the expansion with temp changes.

That is good to know! Does REC document this? I can't find it anywhere. I'm thinking 3/8".

I can also look into the gaskets Steve recommends.

 

[Steve_S]

Thanks Steve, I'll have to look up those products and see if I can get some before I install my panels; I'm pretty close to installing them, so I might just leave a gap. It also sounds like you are implicitly recommending a gap between them.

Edit: And I am using 3 rails per panel, mounted "portrait". We have a high snow load in my area, and the engineer went crazy with mounts.

I'm near Algonquin Park Ontario Canada.. I know snowloads... also how snow & ice can stick to your panels and how those spaces create anchors for the crap to stay there... plus my panels are set to 45 degrees... I'm resetting my arrays and going to 50 Degrees, I'll loose a bit of summer production but improve my winter & snow/ice shedding as well. Gaskets will be applied this time here. A neighbour did them when he installed & I helped that build and Damn.

 

[pollenface]

should I be concerned?

I don't think so

 

[corbin]

I'm near Algonquin Park Ontario Canada.. I know snowloads... also how snow & ice can stick to your panels and how those spaces create anchors for the crap to stay there... plus my panels are set to 45 degrees... I'm resetting my arrays and going to 50 Degrees, I'll loose a bit of summer production but improve my winter & snow/ice shedding as well. Gaskets will be applied this time here. A neighbour did them when he installed & I helped that build and Damn.

I'm in Truckee, California -- one of the heaviest snow areas in the US. 254 psf snow load! (12.2 kPa)

 

[Hedges]

>>Spacing is required on all 4 sides of the panel or you risk breaking them during the expansion with temp changes.

That is good to know! Does REC document this? I can't find it anywhere. I'm thinking 3/8".

I had some rubber rings pulled out to size flashing, and placed a pair of those between panels to hold spacing until clamped. Then pulled them out.

Maybe not an issue with top clamps, at least those with compliance at the plane of the glass. The one with just bolt between panels still would.

I'm in Truckee, California -- one of the heaviest snow areas in the US. 254 psf snow load! (12.2 kPa)

Hope you're calculating Voc adjustment for cold.
I've got panels I can use in a particular string length with a particular SCC for San Jose, but not for Truckee. Matters to me if I put them on a vehicle for winter use up there.