Panel mounting- question about frames

westend

Hi,
First post here and I did search for the answer before starting this thread: Can I support and mount an MX-Solar 235w panel (39 1/2" x 65 1/2") on the short side ends, only, or do I need to support the long sides of the frame? This single panel will be mounted on the roof of a travel trailer. I am building my own mounting system that allows tilt in four axis' and mounting on the short frame sides affords an easy design. Thanks for any help.

Cariboocoot

Re: Panel mounting- question about frames

Welcome to the forum.

I'm not familiar with that brand, but it ought to have at least a data sheet for it including mechanical recommendations.

Quite often panels are simple bolted at four points to two long rails (one 'top', one 'bottom') along either the long or short sides (depending on whether it is landscape or portrait mounting).

The panel frame itself should be self-supporting, whether the mounts are on the long or short sides.

This is why you need to check the maker's recommendations, though.

westend

Re: Panel mounting- question about frames

Cariboocoot wrote: »

Welcome to the forum.

I'm not familiar with that brand, but it ought to have at least a data sheet for it including mechanical recommendations.

Quite often panels are simple bolted at four points to two long rails (one 'top', one 'bottom') along either the long or short sides (depending on whether it is landscape or portrait mounting).

The panel frame itself should be self-supporting, whether the mounts are on the long or short sides.

This is why you need to check the maker's recommendations, though.

Thank you for the quick reply!
I believe the panel's frame is robust enough to support itself but will look at Mfg.'s data sheets to see if the construction will allow. My initial feeling is that it will be OK but I've seen the MO of "it should be OK" fail many times. FWIW, this panel is no longer being built in the US, MX-Solar having closed their stateside plant. The company still has a fairly large Mfg. base and operations in Europe.

Cariboocoot

Re: Panel mounting- question about frames

One clue would be if it has mounting holes drilled in the short sides and the long sides. If it has holes only in the long sides (or no holes at all) I'd be suspicious.

Photowhit

Re: Panel mounting- question about frames

Cariboocoot wrote: »

One clue would be if it has mounting holes drilled in the short sides and the long sides. If it has holes only in the long sides (or no holes at all) I'd be suspicious.

I think this is good info, I know the Evergreen and Suntech instructions (for the panels I have) do NOT allow for short edge mounting, They both have grounding and weep holes on the short edge.

westend

Re: Panel mounting- question about frames

Cariboocoot wrote: »

One clue would be if it has mounting holes drilled in the short sides and the long sides. If it has holes only in the long sides (or no holes at all) I'd be suspicious.

The frame has identical holes drilled with standard separation (2 1/4" OC) between, on all the frame pieces, both short and long. There are two pairs of these holes on each frame section.

Cariboocoot

Re: Panel mounting- question about frames

westend wrote: »

The frame has identical holes drilled with standard separation (2 1/4" OC) between, on all the frame pieces, both short and long. There are two pairs of these holes on each frame section.

That is a very good sign.
Sounds like they were meant for either portrait or landscape orientation.

Still check the data sheet though. Some panels require stiffening members if turned 'round (more flex across the long axis even if it is 'rigid'). For example, Kyocera has some different models of the same panel with an extra 'rib' built in.

westend

Re: Panel mounting- question about frames

Cariboocoot wrote: »

That is a very good sign.
Sounds like they were meant for either portrait or landscape orientation.

Still check the data sheet though. Some panels require stiffening members if turned 'round (more flex across the long axis even if it is 'rigid'). For example, Kyocera has some different models of the same panel with an extra 'rib' built in.

Thanks for cautious affirmation:D The data sheet lists a few engineering ratings but doesn't disclose if the company supports this type of installation. Actually, if the panel broke on top of my RV, I believe I'd have little recourse, anyway. I'm more concerned about future metal fatigue than warranty and do have the ability to further reinforce the frame. I may just go ahead and install a support at midspan of the long side for transportation deployment. It would just be an additional one or two pins to pull for tilting deployment. Do you think anyone would like to see pictures of this 4-way tilt design and if so, is this the correct section of the Forum to do so?

Cariboocoot

Re: Panel mounting- question about frames

Were you planning on putting rails lengthwise beneath the panels, or merely mounting points on the two edges?

It never hurts to toss up some photos of either the proposal or the effort. There's lots of discussion about mounting going on around here. Usually it gets put in the installation section, but we're not that picky.

westend

Re: Panel mounting- question about frames

Cariboocoot wrote: »

Were you planning on putting rails lengthwise beneath the panels, or merely mounting points on the two edges?

It never hurts to toss up some photos of either the proposal or the effort. There's lots of discussion about mounting going on around here. Usually it gets put in the installation section, but we're not that picky.

Cool. The mounting has a full length 1 1/2" x 1 1/2" 6061 aluminum angle along the short sides. This angle is hinged to the panel frame short sides with two 2 1/2" SS hinges. When the panel is flat, it rests inside a full-length "U" channel that is glued and screwed into the roof. I am going to install some gasketing material inside the "U" channel so that the panel frame is not just riding on the two pins of the mounting but will be against an absorbent material for the length of the short sides. I can replicate this for a middle span, also, if needed.
These are the views from the bottom side of the panel.

Complete mount, one side:


Hinge points:



Hinged in one axis:



Hinged in second axis:

Photowhit

Re: Panel mounting- question about frames

I don't understand. you found mounting holes and the chose not to use them? rather you broke the integraty of the box frame of the panel? That doesn't make sense to me...

Volvo Farmer

Re: Panel mounting- question about frames

I wouldn't personally use the solar panel frame as a structural part of your mount like you appear to have done. I believe the hinges should be attached to a mount that would be adjustable and secureable with or without a solar panel on it, then bolt the panel to the mount.

westend

Re: Panel mounting- question about frames

Photowhit wrote: »

I don't understand. you found mounting holes and the chose not to use them? rather you broke the integraty of the box frame of the panel? That doesn't make sense to me...

I drilled 12 holes in the sides of the angle frame to accept the hinges. I don't really see how these 12-5/32 holes impact frame integrity. Can you explain your reasoning on that?

westend

Re: Panel mounting- question about frames

Volvo Farmer wrote: »

I wouldn't personally use the solar panel frame as a structural part of your mount like you appear to have done. I believe the hinges should be attached to a mount that would be adjustable and secureable with or without a solar panel on it, then bolt the panel to the mount.

I had actually thought of this same design. At some point, however, the separate frame needs to be attached to the PV panel frame. Those attachment points are going to be placing load on the frame. The only gain in load bearing would be from doubling the bottom surfaces of the panel frame. Seemed like a lot of material for small gain. What really made me consider it was that, with a separate entire frame, the panel could have been positioned at a compound angle. At that point in R&D, my head started to hurt, how was I going to figure out optimum compound positioning during most of the year.

solarix

Re: Panel mounting- question about frames

All modules I'm familiar with state in their warranty that you cannot drill any holes or modify the module frame in any way. Can't paint them either. Sometimes the spec sheet or mounting instructions require the mounting support to be only in certain areas to meet the snow load spec. Generally, if there are two sets of holes at each end, you have to put the support somewhere between them. Of course, if you don't care about the warranty - do whatever you want.

Photowhit

Re: Panel mounting- question about frames

westend wrote: »

... I don't really see how these 12-5/32 holes impact frame integrity. Can you explain your reasoning on that?

If they were just holes, you just voided your warranty, but they are more than hole they are pivot points for the weight of the panel. Some engineer somewhere had to figure the proper point to secure the panels and signed off on having a hole in that spot, based on the weight of the panel and the orientation of the hole to the weight, based on stresses likely to be present. Evergreen says to use 2 supports up to a 70 mph max wind and 3 or 4 for more than 70 mph (I'm not sure if 70 was the wind speed but since your mounting these on a moving vehicle they are likely to see high wind speed)

westend

Re: Panel mounting- question about frames

Photowhit wrote: »

If they were just holes, you just voided your warranty, but they are more than hole they are pivot points for the weight of the panel. Some engineer somewhere had to figure the proper point to secure the panels and signed off on having a hole in that spot, based on the weight of the panel and the orientation of the hole to the weight, based on stresses likely to be present. Evergreen says to use 2 supports up to a 70 mph max wind and 3 or 4 for more than 70 mph (I'm not sure if 70 was the wind speed but since your mounting these on a moving vehicle they are likely to see high wind speed)

Understood. The warranty I could care less about. If it was at all enforceable, I'd have to ship the panel back to either the seller or the Mfg., in Italy. Both would be cost ineffective. I'm not too concerned with the engineer that decided the holes should be in a certain spot. I've worked enough with metal to know it's characteristics. I would bet that the hole location has more to do with fitting a standard rack than any physics involved. I do plan to have a mid span attachment, more to relieve my own sanity when on the road than anything else. When I'm done with the mounts, it will probably be all of a residential roof system and far exceeds what others are doing for mounting panels on an RV. If we were counting attachment points, I guess that would be 6. I hope you don't think I'm going to hit the freeway with the panel tilted?

Photowhit

Re: Panel mounting- question about frames

I don't expect you to hit the road with the panel up, but there is vacuum to be considered and alluminum doesn't do well with vibrations. I don't think it will lead to the glass cracking, but you might well crack the aluminum....

...I'm a cyclist, and there is an american bicycle company who keep their name "Cannondale" they pioneered alumbinum bike frames but after many early problems earned the name "Crack-N-Fail" after they had a higher than average failure rate in the frames (bottom brackets and tension tube between the BB and headset) They keep the name and offered a life time warranty on their frames and now have a very good reputation.

westend

Re: Panel mounting- question about frames

Photowhit wrote: »

I don't expect you to hit the road with the panel up, but there is vacuum to be considered and alluminum doesn't do well with vibrations. I don't think it will lead to the glass cracking, but you might well crack the aluminum....

...I'm a cyclist, and there is an american bicycle company who keep their name "Cannondale" they pioneered alumbinum bike frames but after many early problems earned the name "Crack-N-Fail" after they had a higher than average failure rate in the frames (bottom brackets and tension tube between the BB and headset) They keep the name and offered a life time warranty on their frames and now have a very good reputation.

I appreciate your concern about the strength of these mounts but this is being done in a similar manner by thousands of RV users across the US. Most of them attach a "Z" bracket in each corner, run in two screws, cover the foot with sealant, and call it a day. Since I live (and play) at 45 degrees North, I'm trying to allow for some tilt.

Trying to improve structural stability of any metal installation is easy if weight, time, and budget are not considered. Fortunately, when dealing with a flat fixture that weighs 40 lbs, and is being mated to another surface that is flat, choice of materials broadens and design can be simplistic. Look at your racking systems for PV that are available, they are very simple in a broad sense, a couple of rails and some tie down clips. I'm using 6061 aluminum in most of this, similar material to standard racking, or better. Those hinge holes I drilled are now filled with stainless steel bolts and have a backing plate afforded by the hinge. The immediate area's structural strength has increased by an order of 10, I'm thinking. Will this create stress on the panel frame in those areas when the panel is tilted, ....yes. Will the frame endure the increased load in those areas....I believe it will. The rating of the panels snow load strength is 5400 pa. That allows a lot of leeway in design, it is nearly twice the strength of IBC rated roofs and bespeaks the module's build characteristics for overall load bearing.

As far as dealing with aerodynamics and vibrational stresses, I'm trying to deal with it as much as possible but anecdotal reports of other RV'ers show that it isn't an issue at all. When you look at the possible forces involved (70 mph wind, the occasional hole/bump in the road), there shouldn't be excessive worry. The wind strikes the panel at it's edge when traveling and the incidental lift or compression is not that great. The road surface oscillation is greatly absorbed by the tires and the vehicle structure. If this weren't true, our highways would be littered with roof top racks, ladders, skis, and bikes.

FWIW, I'm not a novice with metal working and excessive forces. The safety of more than a few folks and the security of millions of dollars of product have been entrusted to my work. Think petro-chemical tankers or food production facilities. I hope my track record in those, and other situations, continues and that I can share a decent way to allow for tilting on top of an RV. I'm not going for a Cannondale, nor a Huffy, more like a Jamis Xenith http://www.bicycling.com/node/60381

NorthGuy

Re: Panel mounting- question about frames

westend wrote: »

Most of them attach a "Z" bracket in each corner, run in two screws, cover the foot with sealant, and call it a day.

With Z-brackets, the panel is mounted to the bracket using mounting holes on the bottom of the panel. That's the same way the panel is mounted to stationary structures.

Mounting holes are located at some distance from the short side, which increases structural strength compare to your method.

They don't use panel's frame as a pivot. IMHO, panel frame by itself is not strong enough to withstand pivoting.

Since it tilts in only one direction, you will have to always position your RV so that the panel would tilt to south, otherwise the pivot will not do you any good.

solarix

Re: Panel mounting- question about frames

The main structural concern with modules is in fracturing the tempered glass. Flex the module too much by say mounting it on the short ends and piling it full of snow and one crack in the glass causes the whole thing to fracture into little bits. Fracking is bad!

westend

Re: Panel mounting- question about frames

solarix wrote: »

The main structural concern with modules is in fracturing the tempered glass. Flex the module too much by say mounting it on the short ends and piling it full of snow and one crack in the glass causes the whole thing to fracture into little bits. Fracking is bad!

If I use a midspan member across the frame in the center will the frame support an average snow load?

westend

Re: Panel mounting- question about frames

NorthGuy wrote: »

With Z-brackets, the panel is mounted to the bracket using mounting holes on the bottom of the panel. That's the same way the panel is mounted to stationary structures.

Mounting holes are located at some distance from the short side, which increases structural strength compare to your method.

They don't use panel's frame as a pivot. IMHO, panel frame by itself is not strong enough to withstand pivoting.

Since it tilts in only one direction, you will have to always position your RV so that the panel would tilt to south, otherwise the pivot will not do you any good.

If you look at the pictures and read the descriptions, you'll see that the mounts are made to pivot in 4 axis'. When the module is tilted in two of those directions, it will be supported by a doubling of it's material dimension, i.e. an additional .125 of aluminum angle iron supports the frame, under the entire short side, and at the middle of the long span.

Man, tough room. If some of these "can't do its" can be based on some knowledge of the specific materials and this mount construction vs conventional vehicle mounting, it would be appreciated.

NorthGuy

Re: Panel mounting- question about frames

westend wrote: »

Man, tough room. If some of these "can't do its" can be based on some knowledge of the specific materials and this mount construction vs conventional vehicle mounting, it would be appreciated.

That's how you engineer things. You try to think of everything that can go wrong, then do try to figure out if what you're doing is able to withstand those bad things. And, in the end, things that you didn't think about get you

When you "hold" panel by the short sides, you double the unsupported span of the long side of the aluminum frame compared to hole mounting. Therefore, the wind load (and snow load too) that they can support now is about 1/4 of what it would be if it was supported at the mounting holes.

Pivoting puts a twisting force on the short side of the frame. I don't think it ever meant to withstand twisting.

These are two specific things that make your construction weaker than the Z-bracket mount.

westend

Re: Panel mounting- question about frames

NorthGuy wrote: »

That's how you engineer things. You try to think of everything that can go wrong, then do try to figure out if what you're doing is able to withstand those bad things. And, in the end, things that you didn't think about get you

When you "hold" panel by the short sides, you double the unsupported span of the long side of the aluminum frame compared to hole mounting. Therefore, the wind load (and snow load too) that they can support now is about 1/4 of what it would be if it was supported at the mounting holes.

Pivoting puts a twisting force on the short side of the frame. I don't think it ever meant to withstand twisting.

These are two specific things that make your construction weaker than the Z-bracket mount.

OK, thanks for your input on the load bearing and "twisting" regarding the tilt mount. That we can discuss. The module in it's original configuration has mounting through holes in the short side, paired-2 1/4" apart. These pairs are located at 9 3/4", 12" from the frame edge. The long side frame also has the same two pairs, spaced-2 1/4". located 15 3/4",18" from the panel edge. The shortest (not to a corner) unsupported span is 18" along the short side, the longest span is 32" along the longer side. The short side mounting brackets I made are at the same location as the mounting holes on the short side, same span length. If I support the long side span in the middle of the panel's span, the resulting two lengths are 32 1/2". I have not increased any of the lengths of unsupported span of the frame. In fact, in it's most used configuration (tilted from the short side corner), the frame is reinforced by the additional 1 1/2" angle pieces under the frame. FWIW, this modules load rating is 5400pa=112 PSF. This is almost double any residential building code regarding snow load for roofs.

I am not understanding your reference to twisting. There is rotation around the locking pins or at the hinge pins.

solarix

Re: Panel mounting- question about frames

I tend to think that the manufacturer's restrictions (like not drilling holes) are overly conservative and reflect the 25 year warranty they provide. When you have that long of a warranty period, I suppose you get a little paranoid about problems - and also a little overzealous about providing "outs" from it.

westend

Re: Panel mounting- question about frames

solarix wrote: »

I tend to think that the manufacturer's restrictions (like not drilling holes) are overly conservative and reflect the 25 year warranty they provide. When you have that long of a warranty period, I suppose you get a little paranoid about problems - and also a little overzealous about providing "outs" from it.

A couple of things come to mind: If my business is producing solar modules, I want them to last so that my customers are happy and promote my business by word of mouth. The least amount of warranty claims paid affords the most profit. There are different ways to reach these goals and some folks travel a higher road than others.

NorthGuy

Re: Panel mounting- question about frames

westend wrote: »

OK, thanks for your input on the load bearing and "twisting" regarding the tilt mount. That we can discuss. The module in it's original configuration has mounting through holes in the short side, paired-2 1/4" apart. These pairs are located at 9 3/4", 12" from the frame edge. The long side frame also has the same two pairs, spaced-2 1/4". located 15 3/4",18" from the panel edge. The shortest (not to a corner) unsupported span is 18" along the short side, the longest span is 32" along the longer side. The short side mounting brackets I made are at the same location as the mounting holes on the short side, same span length. If I support the long side span in the middle of the panel's span, the resulting two lengths are 32 1/2". I have not increased any of the lengths of unsupported span of the frame. In fact, in it's most used configuration (tilted from the short side corner), the frame is reinforced by the additional 1 1/2" angle pieces under the frame. FWIW, this modules load rating is 5400pa=112 PSF. This is almost double any residential building code regarding snow load for roofs.

I don't understand about the support in the middle. If you want to add the support, it must be connected to something, but you do not seem to have anything to connect it to except the frame itself.

It is quite possible that your panel is strong enough for your mounting, especially if it is designed to be mounted on the short side. However, if I were building this, I wouldn't count on the strength of the frame and would build a separate frame that would tilt as I want, most likely with some diagonal element(s) in it and then would mount the panel on top.

westend wrote: »

I am not understanding your reference to twisting. There is rotation around the locking pins or at the hinge pins.

If you open it too wide, the hinge will start to twist the short side out of the panel. Depending on the strength of the panel, it may be enough to do it once to break it out.

westend

Re: Panel mounting- question about frames

NorthGuy wrote: »

I don't understand about the support in the middle. If you want to add the support, it must be connected to something, but you do not seem to have anything to connect it to except the frame itself.

It is quite possible that your panel is strong enough for your mounting, especially if it is designed to be mounted on the short side. However, if I were building this, I wouldn't count on the strength of the frame and would build a separate frame that would tilt as I want, most likely with some diagonal element(s) in it and then would mount the panel on top.



If you open it too wide, the hinge will start to twist the short side out of the panel. Depending on the strength of the panel, it may be enough to do it once to break it out.

I will be attaching the same 1 1/2" x 1 1/2" aluminum angle to the frame in the middle of the long side to the opposing side. This angle piece will be attached to a "U" channel identical to the side mounts but there will be no hinges involved, only locking pins.
Yes, I agree, it would be stronger to mount the module on a secondary frame and then provide for tilting. However, there is considerable cost and time involved for that and is the benefit worth the trouble? Secondly, an additional frame would raise the module another 1" or 2" over the roof. This is more drag, hence, more force on the mounts and module and less MPG.

I am maybe starting to realize that all module construction may not be alike. There is no way on this Planet that the frame would come apart by hinging in any direction. I am guessing that the frame edges will not even deflect a mm. This MX-Solar module is constructed of an outer 1 1/4 x 1 3/4" x 3/4" "U" channel. The cells and acetate backing lie on that smaller edge of the back of that channel, the 3/4". On top of the acetate back and inboard of the "U" channel is another piece of formed aluminum that must be pressed into place during manufacture. So what I have in this module is a frame within a frame and the cells with backing are between the two frame edges. Does that make sense?

NorthGuy

Re: Panel mounting- question about frames

westend wrote: »

However, there is considerable cost and time involved for that and is the benefit worth the trouble?.

It depends. If concerned about time and effort, I would probably go with two fixed panels mounted flat. In nearly any situation that would give me more power than one tilter, and I wouldn't need to go yo the roof to tilt it.

westend wrote: »

Secondly, an additional frame would raise the module another 1" or 2" over the roof. This is more drag, hence, more force on the mounts and module and less MPG.

Not necessarily. You can build a frame from aluminum angles, then mount it so that the "flat" side faces the roof and mount the panel completely inside the frame. The whole construction could be made no thicker than 2", may be 2 1/4". That is actually less than what you have now.

westend wrote: »

I am maybe starting to realize that all module construction may not be alike. There is no way on this Planet that the frame would come apart by hinging in any direction. I am guessing that the frame edges will not even deflect a mm. This MX-Solar module is constructed of an outer 1 1/4 x 1 3/4" x 3/4" "U" channel. The cells and acetate backing lie on that smaller edge of the back of that channel, the 3/4". On top of the acetate back and inboard of the "U" channel is another piece of formed aluminum that must be pressed into place during manufacture. So what I have in this module is a frame within a frame and the cells with backing are between the two frame edges. Does that make sense?

The construction of modules differ. Some are stronger and some are weaker. Most modules are 2" thick, so yours is a little bit on a thinner side. The thickness of the frame metal is may be only 1/16". They are designed to be attached to a fixed base.

westend

Re: Panel mounting- question about frames

NorthGuy wrote: »

It depends. If concerned about time and effort, I would probably go with two fixed panels mounted flat. In nearly any situation that would give me more power than one tilter, and I wouldn't need to go yo the roof to tilt it.

I've thought of this very thing, adding another panel and that may be an upgrade in the future. My wiring layout supports this.

Not necessarily. You can build a frame from aluminum angles, then mount it so that the "flat" side faces the roof and mount the panel completely inside the frame. The whole construction could be made no thicker than 2", may be 2 1/4". That is actually less than what you have now.

Lots of ways to "build a railroad" but if I just doubled the frame, I'd still have to allow for the tilt mechanisms. With the angle frame as suggested, vertical dimension may only increase by a fraction of an inch but is it necessary? These modules are made to be self-supporting with just four attachment points. I'm guessing everyone is concerned about the tilt causing undue stress on a frame that is not specified for that purpose but I'm not. If you look at typical residential installation, the module is attached at four points and is tilted.

The construction of modules differ. Some are stronger and some are weaker. Most modules are 2" thick, so yours is a little bit on a thinner side. The thickness of the frame metal is may be only 1/16". They are designed to be attached to a fixed base.

I'm not familiar with different frame constructions so can't say whether the MX-Solar module is good, bad, or the same. The double walled construction of the assembly means someone was after rigidity in the design phase. This module will be attached to a fixed base (three of them actually), just not secured with clips.

I'm just about finished discussing my efforts with the tilting mounts. There seems to be a commonality of "you have to do it this way or it won't work". Most of the comments have no basis in any real-world metal working, any knowledge of module construction and engineering principles, or even bother to read through my original posts and pictures to see what I'm doing. I'm done defending the attributes or exploring the lack of in this thread. Thanks to those with valid critiques.