mounting panels on a misshaped roof?
eli...@gmail.com
I've been living in a cabin in Hawaii for years now, getting along on
the simple solar system I inherited when I got here - a few old panels
on a rusty rack on the roof; 10 gauge wire going down to an old 15 amp
PCM charge controller, and a collection of old 6v batteries.
However, recent events have necessitated me upgrading this beastie.
The
most obvious room for improvement that I can see is the location of
the
panels - where they are now, they are surrounded by trees (the jungle
grows close to the cabin) so they only receive good sunlight when the
sun is directly overhead.
What I'd like to do is figure out a way of placing them on the peak of
the roof, not on the top of a shed that sticks off the side. This
would
place the panels in a position where they would receive much more
direct
sun, as they would be about as high as the surrounding trees.
However, this is a steep roof - 45 degrees slope - and the peak runs
north-south.
I've been online all evening trying to find a good mounting option;
however, all the modular mounts I can find are for mounting directly
to
the roof, and that won't work here. I thought for a while that
maybe I could poke a pole up through the top of the roof and mount on
that using a pole top mount but everything I read says you need to
embed
that pole in concrete. Is that true? is there a way of doing a pole
mount through a roof?
Do you see my predicament? no existing structure gives me something I
can place a few panels on and get a good angle that's out of the
shade.
a few notes:
during the summer, the sun goes directly overhead (actually, a bit
to
the north) so I'd like to be able to adjust the panels to get close to
laid back flat at that point
it rains a lot here, so we have big overhangs - like 4'+. i thought
of a south wall mount but the overhangs, plus the above mentioned sun
path
during the summer, makes that impractical
many of the trees in question are sweet old growth native forest;
I'm
loath to top them for my project
there is no close place that there aren't tall trees around (for a
ground pole mount)
I guess what I've imagined all along is forming a sort of aluminum
"table" that spans the ridgeline, with four legs going down and tying
into the roof rafters, two on either side. These four legs would be
tied together with a horizontal square of metal, which forms a flat
plane (the tabletop, without any actual tabletop to it) that I can
build
a regular strut-mount on.
Is that my best bet? At best it will be a hack job and I'm a little
nervous to just dive in on something that's going to be punching holes
in the roof and exposing expensive panels to winds, etc, without
anyone
else taking a look at it.
alright, thanks in advance for any help!
e
bea...@gmail.com
You can start with
http://s78.photobucket.com/albums/j103/GGhio/
and look at the drawings for the panel rack. This rack can be modified
to suit almost any structure.
What is the roof made of?
wmbjk...@citlink.net
>I thought for a while that
>maybe I could poke a pole up through the top of the roof and mount on
>that using a pole top mount but everything I read says you need to
>embed
>that pole in concrete. Is that true? is there a way of doing a pole
>mount through a roof?
I've seen a few C-band satellite dishes mounted on a tall pole at the
end of a house. Imbed the pole, and then tie it properly to the
structure, and/or use some angled struts for additional support.
>I guess what I've imagined all along is forming a sort of aluminum
>"table" that spans the ridgeline, with four legs going down and tying
>into the roof rafters, two on either side. These four legs would be
>tied together with a horizontal square of metal, which forms a flat
>plane (the tabletop, without any actual tabletop to it) that I can
>build
>a regular strut-mount on.
>
>Is that my best bet? At best it will be a hack job
Too many variables to say, but your description of a hack job doesn't
bode well. :-) The pole mount has fewer variables if you can manage
it, and gives you the option of going somewhat higher than the roof
line. Either way, you should get somebody with some real experience to
take a look at the job before making a decision.
Wayne
eli...@gmail.com
> On Mon, 25 Aug 2008 15:06:39 -0700 (PDT), "elij...@gmail.com"
>
> <elij...@gmail.com> wrote:
> >I thought for a while that
> >maybe I could poke a pole up through the top of the roof and mount on
> >that using a pole top mount but everything I read says you need to
> >embed
> >that pole in concrete. Is that true? is there a way of doing a pole
> >mount through a roof?
>
> I've seen a few C-band satellite dishes mounted on a tall pole at the
> end of a house. Imbed the pole, and then tie it properly to the
> structure, and/or use some angled struts for additional support.
>
and that's the crux of my question - what is "tied properly" for a 4"
pipe poking up through the roof with a pile of expensive heavy panels
on it? The roof is a big A-frame; I envision putting a series of
horizontal 2x4 "ladder rungs" between one of the 4x4 uprights that
support the ridgebeam, and a rafter, and having the pole run
perpendicular to these rungs, tied to each with a U-bolt. How many
rungs? how many connections? how long should the support area be (is
4' from the bottom to top support enough)?
thanks so much
eli...@gmail.com
those drawings are great - is that your design?
the roof is a corrugated metal roof, directly onto purlins onto
rafters. The spacing on rafters & purlins is rather wide but I can
beef up areas and tie in right next to the rafters. It looks like
you're specifying a foot that has holes spaced as wide as two ridges
on the corrugate, and you bolt through the purlin below.
What material are you specifying there? stainless or aluminum or just
heavy pipe?
It's kind of hard for me to tell - is there just one support leg for
that array of panels or is there one at each intersection of 4 panels
or?
and lastly - this is something I've been dreaming of playing with -
how would you modify that design to allow for a tracker setup? could
there be bearings placed at the top of the uprights, supporting a
horizontal pipe that had crossmembers holding the panels, and a linear
actuator + one of the Redrok trackers to pivot the whole thing? I'm
not a structual engineer so the limitations of that sorta thing aren't
instinctual...
awesome stuff.... thanks
wmbjk...@citlink.net
>On Aug 25, 2:54 pm, wmbjkREM...@citlink.net wrote:
>> On Mon, 25 Aug 2008 15:06:39 -0700 (PDT), "elij...@gmail.com"
>>
>> <elij...@gmail.com> wrote:
>> >I thought for a while that
>> >maybe I could poke a pole up through the top of the roof and mount on
>> >that using a pole top mount but everything I read says you need to
>> >embed
>> >that pole in concrete. Is that true? is there a way of doing a pole
>> >mount through a roof?
>>
>> I've seen a few C-band satellite dishes mounted on a tall pole at the
>> end of a house. Imbed the pole, and then tie it properly to the
>> structure, and/or use some angled struts for additional support.
>>
>
>and that's the crux of my question - what is "tied properly" for a 4"
>pipe poking up through the roof with a pile of expensive heavy panels
>on it?
I was talking about running the pole to the ground. Depends on the
soil, but generally something like 18" square and 6" thick would be
sufficient. The idea is that the bottom of the pole is restrained, and
the down-force is transmitted to a pad or footing that won't sink. If
the pole isn't too long, then some of the side force can be
transmitted to the ground as well by considering the pole as mostly
free-standing, and anchoring it like a post.
> The roof is a big A-frame; I envision putting a series of
>horizontal 2x4 "ladder rungs" between one of the 4x4 uprights that
>support the ridgebeam, and a rafter, and having the pole run
>perpendicular to these rungs, tied to each with a U-bolt. How many
>rungs? how many connections? how long should the support area be (is
>4' from the bottom to top support enough)?
Assuming the wood structure can stand the side force, then anchoring
the pole for say, 8' below the ridge should do it. Maybe 3 brackets.
I'd urge caution though, the amount of leverage an array can exert in
high winds needs to be taken seriously. U bolts alone might allow
fretting. You should post some photos of the structure and more
details if you want to do the job properly.
Wayne
bea...@gmail.com
Yes, based on a friends prototype.
>
> the roof is a corrugated metal roof, directly onto purlins onto
> rafters. The spacing on rafters & purlins is rather wide but I can
> beef up areas and tie in right next to the rafters. It looks like
> you're specifying a foot that has holes spaced as wide as two ridges
> on the corrugate, and you bolt through the purlin below.
Power drive screws or bolts if the timber is a bit sus.
>
> What material are you specifying there? stainless or aluminum or just
> heavy pipe?
The uprights are 40mmx40mmx2mmgal square gal tube
The struts are 40mmx40mm gal angle
The pivots are 32mmN/B gal water pipe. Medium wall
The pipe that holds the panels is 25mmN/B. Medium wall.
The feet are stainless.
>
> It's kind of hard for me to tell - is there just one support leg for
> that array of panels or is there one at each intersection of 4 panels
> or?
It would depend on what sort of wind loading you have.
>
> and lastly - this is something I've been dreaming of playing with -
> how would you modify that design to allow for a tracker setup? could
> there be bearings placed at the top of the uprights, supporting a
> horizontal pipe that had crossmembers holding the panels, and a linear
> actuator + one of the Redrok trackers to pivot the whole thing? I'm
> not a structual engineer so the limitations of that sorta thing aren't
> instinctual...
I have a modification to make mounting bearings easier. They can be
real buggers to align properly. But, yes this rack can be made to
track.
If you want feet I have a box full. You can have some for the price of
postage. They need to be drilled for the width of the iron on your
roof.
>
> awesome stuff.... thanks
eli...@gmail.com
>
> I have a modification to make mounting bearings easier. They can be
> real buggers to align properly. But, yes this rack can be made to
> track.
>
can you give any details or photos of this? this is my long-term
interest, but I'd like to just get the panels up there to start
with...
> If you want feet I have a box full. You can have some for the price of
> postage. They need to be drilled for the width of the iron on your
> roof.
>
>
you mean the stainless bits? that's a really nice offer - my only
concern is that you're giving metric dimensions, which means you're
probably in a pretty expensive place to stuff to/from!
eli...@gmail.com
> >and that's the crux of my question - what is "tied properly" for a 4"
> >pipe poking up through the roof with a pile of expensive heavy panels
> >on it?
>
> I was talking about running the pole to the ground. Depends on the
> soil, but generally something like 18" square and 6" thick would be
> sufficient. The idea is that the bottom of the pole is restrained, and
> the down-force is transmitted to a pad or footing that won't sink. If
> the pole isn't too long, then some of the side force can be
> transmitted to the ground as well by considering the pole as mostly
> free-standing, and anchoring it like a post.
>
now that's interesting - something I hadn't thought of - running the
pole to ground. I have a high peak to my roof so it would be like a
30 foot pole! but it would be a lot more solid.
maybe running it into some of the second floor framing - 4x6 under
there - would be a happy medium; take the pole weight there, and
bracket the shit out of it up above there... hmm...
> > The roof is a big A-frame; I envision putting a series of
> >horizontal 2x4 "ladder rungs" between one of the 4x4 uprights that
> >support the ridgebeam, and a rafter, and having the pole run
> >perpendicular to these rungs, tied to each with a U-bolt. How many
> >rungs? how many connections? how long should the support area be (is
> >4' from the bottom to top support enough)?
>
> Assuming the wood structure can stand the side force, then anchoring
> the pole for say, 8' below the ridge should do it. Maybe 3 brackets.
> I'd urge caution though, the amount of leverage an array can exert in
> high winds needs to be taken seriously. U bolts alone might allow
> fretting. You should post some photos of the structure and more
> details if you want to do the job properly.
>
> Wayne
ok, along those lines - do you (or anyone) know of any source for the
sorts of brackets that tie 4" poles to each other and to framing?
above and beyond u bolts... I know there must be a generic
manufacturer but the only stuff I've seen is through the pole mount
manufacturers...
thanks again!
elijah
bea...@gmail.com
> > I have a modification to make mounting bearings easier. They can be
> > real buggers to align properly. But, yes this rack can be made to
> > track.
>
> can you give any details or photos of this? this is my long-term
> interest, but I'd like to just get the panels up there to start
> with...
Yeah. Will do a sketch for you. Otherwise the rack concept is there.
Roof mount, ground mount even straddle the ridge. It can be adapted.
>
> > If you want feet I have a box full. You can have some for the price of
> > postage. They need to be drilled for the width of the iron on your
> > roof.
>
> you mean the stainless bits? that's a really nice offer - my only
> concern is that you're giving metric dimensions, which means you're
> probably in a pretty expensive place to stuff to/from!
Well the US is almost alone in being imperial. I'm in Australia. I got
the feet quite cheap as I ordered by the hundred when I was doing the
work.
wmbjk...@citlink.net
>
>> >and that's the crux of my question - what is "tied properly" for a 4"
>> >pipe poking up through the roof with a pile of expensive heavy panels
>> >on it?
>>
>> I was talking about running the pole to the ground. Depends on the
>> soil, but generally something like 18" square and 6" thick would be
>> sufficient. The idea is that the bottom of the pole is restrained, and
>> the down-force is transmitted to a pad or footing that won't sink. If
>> the pole isn't too long, then some of the side force can be
>> transmitted to the ground as well by considering the pole as mostly
>> free-standing, and anchoring it like a post.
>>
>
>now that's interesting - something I hadn't thought of - running the
>pole to ground. I have a high peak to my roof so it would be like a
>30 foot pole! but it would be a lot more solid.
I must have missed the 2 story part, 30' takes away some of the
advantages.
>maybe running it into some of the second floor framing - 4x6 under
>there - would be a happy medium; take the pole weight there, and
>bracket the shit out of it up above there... hmm...
Definitely doable.
>ok, along those lines - do you (or anyone) know of any source for the
>sorts of brackets that tie 4" poles to each other and to framing?
>above and beyond u bolts... I know there must be a generic
>manufacturer but the only stuff I've seen is through the pole mount
>manufacturers...
It's likely to be best to weld up custom hardware. Saves time shopping
and saves money over buying off-the-shelf hardware. Check out salvage
yards for the heavier bits. Here's an example of a scratch-built
pole-top tracker that uses an inexpensive linear actuator
http://www.citlink.net/~wmbjk/tracker.htm, and here's a link to a site
with many more examples plus affordable controllers
http://www.redrok.com/led3xassm.htm#led3xforsale.
Wayne
Roderick
I don't know if you have the space or the money, but is there any
place on the ground you could put a free standing structure? We have
a lot in HOVE (Ocean View Estates, on the lava flow on the big
island), and I was thinking, the panels should go on a covered lanai,
not on the house itself. That way, you get a little shade, can put a
table and some chairs under it, and the roof doesn't need to be 100%
waterproof. I would not put the panels flat to try to capture optimum
sun at Lahaina Noon in the summer. Not too much will be lost by
putting them at 20 degrees year round, and besides, if you have a
separate structure, you can point the panels due south. And also, if
you don't slant the panels, bird droppings and dirt will collect on
them, then the rain will dissolve it, puddle up on the panels, and
leave behind a scummy coating the reduces your output.
I admit, though, shade is at a premium on the lava flow. There are no
big trees, just some really small, stunted Ohia. If you live near the
jungle, then you might have all the shade you want already - not worth
making a covered patio.
Duane C. Johnson
> It's likely to be best to weld up custom hardware.
> Saves time shopping and saves money over buying
> off-the-shelf hardware. Check out salvage yards for
> the heavier bits. Here's an example of a scratch-built
> pole-top tracker that uses an inexpensive linear
> actuator
> http://www.citlink.net/~wmbjk/tracker.htm, and here's
> a link to a site with many more examples plus affordable
> controllers
> http://www.redrok.com/led3xassm.htm#led3xforsale.
See this mount:
http://www.redrok.com/led3xassm.htm#lancette
> Wayne
Duane
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eli...@gmail.com
>
> I don't know if you have the space or the money, but is there any
> place on the ground you could put a free standing structure? We have
> a lot in HOVE (Ocean View Estates, on the lava flow on the big
> island), and I was thinking, the panels should go on a covered lanai,
> not on the house itself. That way, you get a little shade, can put a
> table and some chairs under it, and the roof doesn't need to be 100%
> waterproof. I would not put the panels flat to try to capture optimum
> sun at Lahaina Noon in the summer. Not too much will be lost by
> putting them at 20 degrees year round, and besides, if you have a
> separate structure, you can point the panels due south. And also, if
> you don't slant the panels, bird droppings and dirt will collect on
> them, then the rain will dissolve it, puddle up on the panels, and
> leave behind a scummy coating the reduces your output.
>
> I admit, though, shade is at a premium on the lava flow. There are no
> big trees, just some really small, stunted Ohia. If you live near the
> jungle, then you might have all the shade you want already - not worth
> making a covered patio.
Hey - I'm just up the road from you, in Fern Acres, sorta between
Volcano and Keaau!
The real problem is that I'm in tall jungle - lotsa 600 year old
ohias. They come right up to the cabin and the effect is wonderful -
full wall windows that look out into the ferns. But the placement of
the panels means that they're shaded for a lot of the day. The best
way to beat that is move them up to the peak of the A-frame - 30'+ in
the air...
If I had a wide open lot like yours, it would be a different story!
elijah