Portrait vs Landscape layout...does it matter?

[skanmyth]

Very nice skanmyth. I wouldn't want to get on tbat top roof level. Did you photograph that with a drone?

This is not my installation or I am not related any way to installer or home owner I saw this when I was looking into how others clamping the panels to raking - short or long side of panel.

[skanmyth]

My comments. A landscape panel in theory can start producing when 1/3 of the snow
slides off, which generally will uncover the first section (running the long way) with the
other 2/3 bypassed. However the available voltage will be only 1/3, so this will be
usable only if the inverter system can operate in that mode.

Second, I'm leaving a big gap between panels in the downhill direction, so the snow
only has to clear the short way across one panel instead of several. That never gets
mentioned, but will get built here eventually. I suppose that is only practical with a
ground mount.

This costs more? Yea, so does having panels covered with snow. Bruce Roe

Thanks for the info. I have a 36 cell panel I built have been using to test particular areas of roof to see production when I have a minute I will test your theory by covering with a cardboard bottom half for landscape and another test for portrait and will let you know if there is difference.

[skanmyth]

I really can't believe what I'm reading . I agree with post 6 . OP the company that was telling you the landscape to be avoided if possible was right. But it can be done.
If you have a row of landscape panels going up the rails will be attached to the same 2 rafters in paralel . All the brackets on one rail will hit the same rafter . That is a lot of weight and stress from one row of panels on 2 rafters . What is required in this situation is to double up the loaded rafters in the attic so it eliminates the flex . Same goes for prefabricated trusses. There is no such thing horizontal trusses .
When your panels are in portrait you don't use the same rafter for the brackets , the top rail can be alternate / staggered ; if that's not posible for eny reason then the next row can , so you don't load the same rafter all in line up. Think of it you got a decking with the joists exposed , wich way are you going to sheet it up ? Paralel or across? Every survey I came across the structural engineer allowed for loaded rafters reinforcements on landscape and staggered loaded points on portrait.
Same goes for clamping on the short side , unless the frame is strong enough and the manufacturer specifies in they spec that short sides clamping is allowed. Otherwise you will leave the panel unsupported on its length and will flex more than permitted tolerances , hence snail trail and cell failure in the short future. Take a Lg 285 mono and compare it to a trina 240 silver C Chanel 40mm framed . The lg will flex like paper while the trina is solid. Not all panel frames are the same , to keep cost down some frames are less beefy than it used to.

Not sure if you responded to me or to thread starter HX Guy - I responded with a link for anyone ells who have interested installing landscape. If done properly with engineers assist I don't see an issue. I have not shopped around for solar installers so no one have refused to install landscape orientation for me.

City I live in Ontario I have to get a permit from city to install solar panels a) to make sure no zoning restriction and b) a structural engineer have to review and approve. If rails not placed into enough rafters engineer is going to suggest approve based on extra braising in attic etc.. I am from construction background doing any extra work if engineer request is not a big deal. I will update all here how my project progress with landscape installation.

HX Guy - sorry for highjacking your thread I hope you completed your installation to your liking.

[PNjunction]

Just a quick note about portrait mounting - I was told that if you do so, it is best to have the junction boxes at the bottom to allow for convection cooling to help cool the bypass diodes or whatever you have inside them. With heat rising, having them at the top, and especially if surrounded by deep panel channeling, can make whatever is inside the junction boxes run hotter.

Sounds reasonable, but since I don't have any roof mounted panels, this could be urban legend for all I know.

Still, even for my temporary use with portrait-mounted panels, I'll keep the junction boxes on the bottom side for a feel-good function.

[skanmyth]

PNjunction - Thanks for your information I will keep that in mind and look into if there is logical reasons to keep the box in bottom for my location - I just updated my profile to show where I live we go through more cold and normal temps than hot weather here so I don't think collecting heat under panel is an issue for me. My primary concern will be with the manufacture I pick how box have been sealed between wire and box and in long run if seal give up how I can avoid water getting in if place box top or bottom.

[bcroe]

Thanks for the info. I have a 36 cell panel I built have been using to test particular areas of roof to see production when I have a minute I will test your theory by covering with a cardboard bottom half for landscape and another test for portrait and will let you know if there is difference.

Generally sections of a panel each have a bypass diode; 3 for many panels. When a section
is entirely uncovered (snow), it can start to function. Sections partly obscured will be bypassed.
If you built your own panel, the sections will depend on how you wired bypass diodes. Bruce Roe

[skanmyth]

Generally sections of a panel each have a bypass diode; 3 for many panels. When a section
is entirely uncovered (snow), it can start to function. Sections partly obscured will be bypassed.
If you built your own panel, the sections will depend on how you wired bypass diodes. Bruce Roe

You're absolutely correct panel without bypass diode would be not proper panels to test the theory. My home made panel is not installed with bypass diodes.
If the panel have been separated into 3 strings and strings are running long side of the panel in theory you are correct if top side or bottom side of a landscape panel has snow other half should be able to generate power. I have to wait till my installation to test with a factory made panel.

My big question is if there is a way to generate lets say 20% more solar power during winter months on landscape orientation installation why still portrait orientation is still popular my guess is if there is some cells are exposed to light and most of them are covered with snow the one's covered with snow would heat up and would quickly melt the snow away so another way it may not matter if its installed landscape or portrait for snow covered panels.

Out of 40 panels I will have 9 portrait panels I think during snow time I should be able to compare side by side for landscape and portrait how it generating power and how soon each one melting the snow away etc..

[skipro3]

Didn't read of this, so forgive me if this has been already mentioned.

While landscape uses more rail, it supports the panel the least. You see; the landscape mount has the rails running the length and the panel can bow, only being supported on it's ends. Portrait the panels are supported more towards the middle.

Most panel mfg. will list a much lower pounds-per-square foot for loading on a landscape panel mounted with length running rails.

[bcroe]

My big question is if there is a way to generate lets say 20% more solar power during winter months on landscape orientation installation why still portrait orientation is still popular my guess is if there is some cells are exposed to light and most of them are covered with snow the one's covered with snow would heat up and would quickly melt the snow away so another way it may not matter if its installed landscape or portrait for snow covered panels.

Out of 40 panels I will have 9 portrait panels I think during snow time I should be able to compare side by side for landscape and portrait how it generating power and how soon each one melting the snow away etc..

When I came on the scene, PV solar was designed for SW desert operation
on rooftops. I heard little mention of clouds and snow, and a roof could better
support portrait mounted panels.

In these parts there is a lot of snow and even more clouds. With a ground
mount the support is no longer an issue. Lately the price of the panels no
longer dominates the total installation cost. After a couple winters, I would
like to minimize the time spent clearing snow (at sunrise). No increased
energy production, but less work.

Sometimes evening snow hits still warm panels and slides down a foot or
so. If it only needs to slide a foot or 2 and onto the ground, the sun may very
well do the job next day. Or, I won't have to do so much pushing. Currently the
snow here must travel 10.5 feet over a couple butted portrait panels, which will
never happen by sun power, and is quite a bit of work for me. Experiments
have been and are still running here; lets see more results after more winters.

Bruce Roe

[SunEagle]

When I came on the scene, PV solar was designed for SW desert operation
on rooftops. I heard little mention of clouds and snow, and a roof could better
support portrait mounted panels.

In these parts there is a lot of snow and even more clouds. With a ground
mount the support is no longer an issue. Lately the price of the panels no
longer dominates the total installation cost. After a couple winters, I would
like to minimize the time spent clearing snow (at sunrise). No increased
energy production, but less work.

Sometimes evening snow hits still warm panels and slides down a foot or
so. If it only needs to slide a foot or 2 and onto the ground, the sun may very
well do the job next day. Or, I won't have to do so much pushing. Currently the
snow here must travel 10.5 feet over a couple butted portrait panels, which will
never happen by sun power, and is quite a bit of work for me. Experiments
have been and are still running here; lets see more results after more winters.

Bruce Roe

I know it would be a big expense for you but I would think if the panels were elevated higher off the ground there would more space for the snow to slide off the panels and fall onto the ground.

Maybe a Pole mounted array might be a better option for snow country due to the height of the lowest panel being a few feet..

[bcroe]

I know it would be a big expense for you but I would think if the panels were elevated higher
off the ground there would more space for the snow to slide off the panels and fall onto the ground.

The next version will be another foot higher above the ground. But what I am saying, is its only 39"
down and off a panel in landscape. Its 63" in portrait and 126" when 2 are touching. Bruce Roe

[HX_Guy]

Didn't read of this, so forgive me if this has been already mentioned.

While landscape uses more rail, it supports the panel the least. You see; the landscape mount has the rails running the length and the panel can bow, only being supported on it's ends. Portrait the panels are supported more towards the middle.

Most panel mfg. will list a much lower pounds-per-square foot for loading on a landscape panel mounted with length running rails.

Wouldn't that be quite the opposite?

With panels in landscape, the rails would run parallel to the long side of the panel therefore giving it more support. A panel isn't going to bow anyway, but if it were to bow, it would bow along the 65" side, not the 40" side.

[skipro3]

No
Think about the 4 points of contact. The long side has no support and will bow in the middle. Panels are hollow and only the frame to rail contacts provide support. The length Will sway like an old horses back. I know....

[mpkelley20]

My installer is sending me a couple of options for my system. One that would allow me to expand a bit in the future (if needed) is attached. It has both portrait and landscape design. My roof is very solid with 2x8 beams (2x6 is standard in my state). Is this a design you would consider in an area that gets snow several months out of the year? My installer said this design is the most efficient of the ones he is looking at.
The cost, whether it is landscape or portrait does not change. He wanted to give me the most efficient design that leaves room for some upgrades later. He did say that landscape design on the panels is a little better in snow conditions.

One other thing, my installer is complete opposite from another installer who wanted to leave tons of space on te roof so you could walk around on it. The guy I hired obviously doesn't leave any space on the main house. His claim is that leaving parts exposed will cause those parts of the roof to detiorate quicker (albeit still 20+ years) than the part that is covered. And he said the Solarworld 285 panels are so strong that you can walk on them (I think he even said drive on them.


Sorry for the rough drawing but I asked for this on short notice to get feedback here.

[emartin00]

Some local authorities require you to comply with the NFPA rules that require 3ft on the top and sides of the array. That may not be the case for you.
The orientation shouldn't matter for snow load.
As far as walking on the panels, although they may not show any signs of damage, excessive stress can cause micro cracks in the silicon, which will lead to lower output.