nvreloader
Western Nevada
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Joined: 12/08/2006
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Ok Guys,
I think, I got cross threaded again and need some help, if you be so kind, to help me out. I know, what a zebra feels like when he is surround by a bunch of solar lions, waiting to pounce.  
I am not too worried about being precise on the angles, the sun's main arc/travel path is East to West, (as we all know, at least in MY part of this world), the RV is parked with it's main length running East to West, tongue facing East, front door is facing South.
During the summer months, when the sun's angle is approximately overhead, there is no major problems.
But, during the Winter months, up jumps the problem, as the AC Unit, 16" Tall, looks like it will cast a shadow on 1 of the panels, which I do NOT want, if I can help it. 
There are 2-Solar Panels mounted/running length ways on each side of the RV,(4 total).
The 2-Solar Panels on the South side, left side, we are facing the RV from the front, will receive the sun's rays at a better angle, as the panels are tilted/angled 5" down towards the sun, this is because of the 5" crown/drop from the centerline to each side of the RV
The 2 Solar panels on the North side, right side, are facing away, tilted/angled down because of the 5" drop on the North side of the crown.
I will lose a lot of the effeciency of those 2-SP on the North side, unless they are brought up to the approximate level straight across the roof line.
I had planned on mounting all the SP level across the roof to start off with, so I will need to bring up BOTH sides of the down hill edges (North/South) sides of the panels up approx 5" and then all the panels would be relatively level across the roof's surface and receiving the sun's angle at the same time.
This does not take into concideration of the winter time sun angles, (very low parabolic arc/travel) which would be worst for the 2-SP that are mounted on the North side away from the sun's main angle.
I have to build the tilt/angle braces to allow the approximately 60* angle needed to get the most power from the panels during the winter time use plus to also take into account of the North side 5" down slope roof angle etc.
Question:
How much more angle(in degrees), do I have to add for this 5" slope angle, I keep comning up with 12* to 15* more angle needed to be level with the roof peak.
What is the Suns angle during the winter time (Dec), approximately so many degress from the horizon, for N-40.17 and W-118.47?
This does not sound or look right to me.  Meaning that, (as an example), I need 60* of tilt angle for winter time use, PLUS 15* more for the slope angle, which adds up too 75*+ of angle etc????
I hope, I make sense attempting to explain the above info, talk about not be able to show what you are talking about is frustrating, when using this computer, if I could just draw on this plastic box, it would be so much easier.
Tia,
Don
2010 F-350,6.4PSD, 6spd man trans,CC,SWB,SRW, Caravan camper shell,50 gal bed tank,17,000lb Husky WD hitch,2008 28KS Desert Fox TH,2005 Honda 500 Rubicon ATV w/rumble seat,2 Aussie's waiting,watching and ridin shotgun on the whole outfit.
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MrWizard
Van Nuys, Ca
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Joined: 06/27/2004
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your over doing it
#1 all angles are measured from the level
what ever the angle, it is from above level, the ARC in opposite direction has nothing to do with ANGLE, it only affects the length of the brace needed to reach the angle you want, the crown of the roof is the level/pivot point for the panels on the north side, the 5"drop means the brace has to be 5' longer to raise the panel to the calculated angle
assuming your raising the panel on width, hinging the length (long side) 60* is an equilateral triangle and the brace is the same length as the width + the 5" drop need to reach the lower edge of the crown
a a panel 60" long 30" wide would use a 35" bracket on the back side to achieve a 60* angle
the bracket would be at 60* to the roof and at 60* where attached to the panel
60* is too much, your inclination will probably be no more than 45* and possibility closer to 30*, and will have to be corrected to a lessor angle in the summer if you go to high
there are many solar sites that will give you the optimal full year angle for your location
( for you math engineering purists, yes it will be slightly less than 60* because my math is using the 5" drop in the crown and NOT the slight additional length incurred when moving the brace to the 60* angle which lengthens that 5" drop
BTW: my panels are flat mounted
i find that parking North/south gives me the best sun on all panels thru out the day with minimum shade effect, and minimum, solar heating on the sides of the RV
* This post was
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edited 02/04/12 12:19am by MrWizard *
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pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi Don H.,
The panels need to be installed at an angle so they will drain. Use the curve of your roof to assist them to do that. I'd install so the middle of the panel touches the roof when they are down. Others may disagree with that.
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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korbe
Northern California
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Joined: 11/20/2009
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If your rig is 8 feet wide and the center is 5-inches above the outside edges, then the straight angle would be near 6°. I have read that for fixed panels, and for year round solar use, this formula is used for determining your angle: "If your latitude is between 25° and 50°, use the latitude, times 0.76, plus 3.1 degrees". So in my neck of the woods, the angle would be 34° at a latitude of 40°.
So, if you want to determine the angle, add 34° and the roof slope of 6° = 40°. Forty degrees is approx. 36" rise at the outside edge of your rig back down to the center.
Now the math experts can come in and tear this apart, but maybe you will then get an exact figure by them doing so. Good luck.
2004 F250 SD PSD
2004 Crossroads Cruiser CF25RS
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nvreloader
Western Nevada
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Joined: 12/08/2006
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MrWizard wrote:
60* is too much, your inclination will probably be no more than 45* and possibility closer to 30*, and will have to be corrected to a lessor angle in the summer if you go to high
there are many solar sites that will give you the optimal full year angle for your location
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Mr Wizard,
Thank you for the info, ?? on the 60* angle, here is the site I used to figure out the panel tilt angle, go down to the section labeled:
Tilt Fixed at Winter Angle and for my Latitude 40°,Tilt 59.6° = (my location is for N-40.17 and W-118.47), I rounded off the 60* angle.
Am I doing this Right?
Tia,
DonH
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nvreloader
Western Nevada
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Joined: 12/08/2006
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korbe wrote:If your rig is 8 feet wide and the center is 5-inches above the outside edges, then the straight angle would be near 6°. I have read that for fixed panels, and for year round solar use, this formula is used for determining your angle: "If your latitude is between 25° and 50°, use the latitude, times 0.76, plus 3.1 degrees". So in my neck of the woods, the angle would be 34° at a latitude of 40°.
So, if you want to determine the angle, add 34° and the roof slope of 6° = 40°. Forty degrees is approx. 36" rise at the outside edge of your rig back down to the center.
Now the math experts can come in and tear this apart, but maybe you will then get an exact figure by them doing so. Good luck.
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Korbe,
Thank you,
The width of the TH is 8'6" wide, and there is a 5" rise of the above the outside edges.
Tia,
DonH
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nvreloader
Western Nevada
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Joined: 12/08/2006
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pianotuna wrote:Hi Don H.,
The panels need to be installed at an angle so they will drain. Use the curve of your roof to assist them to do that. I'd install so the middle of the panel touches the roof when they are down. Others may disagree with that.
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Don,
Thank you,
I never thought about using the roof slope angle to help keep the panels drained/cleaned of snow/frost etc.
Tia,
DonH
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MrWizard
Van Nuys, Ca
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Joined: 06/27/2004
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nvreloader wrote:MrWizard wrote:
60* is too much, your inclination will probably be no more than 45* and possibility closer to 30*, and will have to be corrected to a lessor angle in the summer if you go to high
there are many solar sites that will give you the optimal full year angle for your location
-------------------------------------------------------
Mr Wizard,
Thank you for the info, ?? on the 60* angle, here is the site I used to figure out the panel tilt angle, go down to the section labeled:
Tilt Fixed at Winter Angle and for my Latitude 40°,Tilt 59.6° = (my location is for N-40.17 and W-118.47), I rounded off the 60* angle.
Am I doing this Right?
Tia,
DonH
you can use 60* for winter, If you want to reposition the panels too 25* optimal for summer
for year round use the various 'calculator websites suggest 33.5 to 35 degrees
my own math 41x0.76 + 3.1=34.26 degrees
do you want too go 6 months winter position and 6 months summer position
or do you want to set it up and leave it
the steeper 60* angle will really reduce the summer total power
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nvreloader
Western Nevada
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Joined: 12/08/2006
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Mr Wizard,
Thanks for the info,
I had planned on tilting for winter time use and then using flat the rest of the year. My main concern is the winter time use, when I need everything I can get, so to speak.
Since the AC sticks up 16" high and because of the limited space I have for the 38"-39" wide panels, going into a 40" space, does not leave me much room for adjustment on the 1 panel that will be the closest to the AC, mounted on the North side of the roof.
From learning from the guys, I know that winter (Dec 21?) is the lowest sun angle possible at this time of year, and everything starts to raise from that time etc.
Do you know of a site that states the sun's angle from the horizon for that date at my Lat/Lon. I then could set up my scaled drawing and find out if the AC will hit this panel and how long of a shadow it would cast etc, to find the correct panel placement.
Per info recieved from the guys, I should use the largest (watts wise) panels possible, and still stay within the safe limits of the MS MPPT controller.
If the AC puts a large shadow on this one panel, I may need to use a smaller (width wise set of panels as close to the larger panels spec's, of 26+"), this would allow me to move the panel farther away from the AC shadow area, within the 40" space limits on the roof, making it shadow free.
Tia,
DonH
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pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi Don H.,
Since you plan to tilt, why not make a mount that would raise the base of the shade troubled panel up above the level of the air conditioner shroud when it is deployed? I believe the term for such hinges are "accordion".
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