Portrait vs Landscape Racking?

[Willaby]

Looking at the portrait layout vs landscape, I like the landscape fit in my situation but installer says this will require 10 extra standoffs which will cost more. Why the extra standoffs? I have a small amount of morning shade which, in landscape, will shade just the one panel, but partial of two panels in portrait. Seems simple, the whole array design just needs to be rotated 90 degrees?

[inetdog]

Looking at the portrait layout vs landscape, I like the landscape fit in my situation but installer says this will require 10 extra standoffs which will cost more. Why the extra standoffs? I have a small amount of morning shade which, in landscape, will shade just the one panel, but partial of two panels in portrait. Seems simple, the whole array design just needs to be rotated 90 degrees?

If the racking is attached to the rafters of the roof system, which run from peak to eaves, the easiest way to run the lower layer of racking is parallel to the ridge so that it is not limited by the rafter position. The top layer of racking then runs from peak toward eave, and since most panels need to be supported along their long edge, you are stuck with portrait.
You can adjust this to fit landscape, but with more parts and more complexity.

[Willaby]

If the racking is attached to the rafters of the roof system, which run from peak to eaves, the easiest way to run the lower layer of racking is parallel to the ridge so that it is not limited by the rafter position. The top layer of racking then runs from peak toward eave, and since most panels need to be supported along their long edge, you are stuck with portrait.
You can adjust this to fit landscape, but with more parts and more complexity.

The installer said it would be 32 mounts vs 22 for portrait. I'll ask a few questions when I get the chance, but the standoffs I have can mount 0-4" off the center of the rafters. So at 16" between the rafters, I can get within 8", then the racking has a range of mounting area, then the panels themselves have a permissible range for mounting. So I'm just not sure why all this variable range still makes it difficult (but I'm not an engineer either).

Maybe it is because there is a 36" maximum between mounts and rafters are 32" apart (every other), so the 4" eventually adds up to another row or two? (I need to get out my ruler and calculator)

[emartin00]

It's simply geometry really. I was thinking about going landscape for a little while until I found exactly what you did.

Racking systems are optimized for portrait mount. Say in portrait you have 2 rows of 6 panels. That means you only need 2 rows of rails. If you wanted to cover the same area in landscape, you would have 3 rows of 4, and thus, 3 rows of rails. More rows means more standoffs. (this is very generalized of course)

[Panelmal]

Panels on rails can only overhang the standoffs by no more than 25% the dimension of the panel. This includes vertically and horizontally. Landscape orientation doubles the amount of standoffs and rail needed to accomplish this on most rail systems.

[Ben25]

Also depends on what type of rail and what size. We normally install ironridge, but have recently been doing a couple jobs for RGS and Centrosolar who use unirac. From an installers point of view, ironridge is far superior.

[Naptown]

My preference is snap n rack
Like their flashed l foot and flush end clamps.

[bcroe]

Landscape VS Portrait

Looking at the portrait layout vs landscape, I like the landscape fit in my situation but
installer says this will require 10 extra standoffs which will cost more. Why the extra standoffs? I have a small
amount of morning shade which, in landscape, will shade just the one panel, but partial of two panels in portrait.
Seems simple, the whole array design just needs to be rotated 90 degrees?

My next design will use landscape mounts, whatever the complications. Driving that is snow, which has to slide
126" to clear 2 panels mounted portrait. Panels will have an 8" gap to keep snow from sliding from one panel to
another; it will slide off in only 39". And it won't take so much leverage to change tilt of a couple landscape panels,
compared to a couple portrait panels. Bruce Roe

[J.P.M.]

My next design will use landscape mounts, whatever the complications. Driving that is snow, which has to slide
126" to clear 2 panels mounted portrait. Panels will have an 8" gap to keep snow from sliding from one panel to
another; it will slide off in only 39". And it won't take so much leverage to change tilt of a couple landscape panels,
compared to a couple portrait panels. Bruce Roe

If on a roof, I'd watch for ice dams/buildup in/around/under the gap.

Edit: This post was added for the OP's situation which seems to be a roof mount. I'm aware that Bruce has what amounts to a small solar farm.

[inetdog]

Panels will have an 8" gap to keep snow from sliding from one panel to
another; it will slide off in only 39". And it won't take so much leverage to change tilt of a couple landscape panels,
compared to a couple portrait panels. Bruce Roe

Have you confirmed that the 8" gap is enough to avoid shading in the tilt range you need to support?

[Naptown]

His panels are ground mount IIRC
And on wood frames.

[bcroe]

Have you confirmed that the 8" gap is enough to avoid
shading in the tilt range you need to support?

These south facing panels will all be in the same plane (same as before), so no issue with shading by sliding them
apart a bit. Just hope 8" is enough to discourage snow bridging. With a hinge at center, 86" will be a lot easier to
pivot than current 126" with the pivot at one edge. Since the array is lower overall, it will take more length to
accomplish the same area. This will be done with several rows (ranks) in the center of the clearing, to avoid early
shading. The extra ranks don't take more space; being lower, they can be spaced closer than a tall array.

S panels will probably be set vertical for the whole snow season. Summer, an option would be to set them horizontal
as sun day extremes puts the sun pretty far north. Everything here is ground mounted at this time.

The E and W facing panels would be similar landscape but fixed near vertical.
Bruce Roe

[utjx98]

My preference is snap n rack
Like their flashed l foot and flush end clamps.

Usually, portrait can have more solar panel installed and with fewer racks. But regards to efficiency when there is shade, landscape is better.

[ButchDeal]

regards to efficiency when there is shade, landscape is better.

This is highly dependent on the nature of the shade (shadows) ..

[bcroe]

Usually, portrait can have more solar panel installed and with fewer racks. But regards
to efficiency when there is shade, landscape is better.

I don't really understand that; do you mean the frame blocking sun to the edge of the cells? With 6" cells I
would expect that effect to be negligible until the sun was at such an extreme angle as to be greatly reduced
in intensity. Before that point here, surrounding shadows would dominate.

Racking, whatever it takes to achieve results, it takes. Much easier to experiment with on the ground. I
started with concrete & 6061 aluminum, but treated wood is now being used where completely stationary
and not in direct contact with panels. The wood is far cheaper installed, and a lot easier to get rid of if plans
change later. Just saw it off below ground level and cover it over. I bury frames with cross pieces, so they
can't move around like a simple post.

Just how the wiring will go with landscape, I haven't figured out yet. Probably about every other jump will
need an MC4 "extension cord", will make whatever it takes. Bruce Roe