The shade pattern will change, throughout the day, if you remain stationary.What happens when you are parked under a canopy of trees? Yes it will reduce the output of the panels but I dont think noticable enough. Rather 2" off the back end than 12" up in the air. My panels for the stock waterers are near some trees that produce shade for a few hours everyday. Never had an issue with not charging the batteries, ever! Didnt want to cut down the trees, they are pretty old and didnt want to run heavier guage wire for the longer distance required to move the panels into permanent sunlight.
I'd strap the sides that hang over the end of the rv with angle aluminum for the whole length of those sides. Move the panel as far back as you believe is safe. Install it with at least a 5 degree tilt, raising the air conditioner end of the panel. When boondocking park facing north and there will be zero shade on the panel.
Place air tabs or some other sort of air deflector in front of the panel to stop it from acting as an air scoop.
We did exactly what You are proposing!I used aluminum angle to create a mount that was attached only at the 4 A/C Cover Bolts. You actually need 2 Rails and 4 Mounting Pieces about 3 Inches long. I Didn't worry about any Tilt because it would just create more failure points! Used Stainless Bolts and Nylock Nuts!
Rob & Jean
98 Dutch Star Diesel Pusher ..92 Tracker 4X2
We did exactly what You are proposing!I used allumium angle to create a mount that was attached only at the 4 A/C Cover Bolts. You actually need 2 Rails and 4 Mounting Pieces about 3 Inches long. I Didn't worry about any Tilt because it would just create more failure points! Used Stainless Bolts and Nylock Nuts!
Hey Rob, I don't suppose you have a picture? I'm having trouble visualizing your setup. What do you mean attached only at the 4 A/C cover bolts?
You might want to make a roof top to scale drawing = 1" = 1foot, and then plot the locataion of everything on the roof and it's height also, then make a scaled piece of card broad for the type of panel you want to use and see the best fit/location etc, might save some headaches later on.
Might be easier to mount the panel towards the front over the vent etc, and then add tilting legs to which ever side that will be work for you.
I went from 4=135w panels to 4-220w panels to build my winter time solar package, summer time I don't have to worry about anything and all we do is boondocking.
2010 F-350,6.4PSD, 6spd man trans,CC,SWB,SRW, Caravan camper shell,50 gal bed tank,17,000lb Husky WD hitch,Northwoods 2008 28KS Desert Fox Toy Hauler,2005 Honda 500 Rubicon ATV w/rumble seat,1 Aussie waiting,watching and ridin shotgun on the whole outfit.
You really need to mount the panel about 1" off the roof, not over the top of the A/C unit.
Have you ever seen a car going down the road with a mattress strapped to the roof? That thing is practically folded back in half due to the wind getting under the front of the mattress. There is a lot of pressure in wind at 70 MPH it is 14 pounds per square foot! So that solar panel will act like a wing, and probably lift itself off the mounts at that speed, come crashing down onto a car behind you (or through the windshield killing someone).
Carefully measure the spaces that you have on the drivers side of the A/C unit, and behind the A/C unit. Maybe even find panels that are say 22" X 39" and them make cardboard cut-outs and see if they will fit before ordering the panels. Get ones that will fit around your A/C unit without putting them on top of it.
For mounts, I used 6" long 2" angle aluminum, with 3 holes 3/16" into the roof with #10 screws, and a 5/16" hole and 1/4-20 bolt into the solar panel frame. I used Nutserts into the solar panel frame, and tamper resistant bolts to hold them snugly against would be theft. I used a generous amount of rubber roof sealant, and this seems to hold the mounts down well, even if the screws do not bite into the metal roof cross pieces. 15 years, no panel movements.
Don't worry about a little shade on the panels, it really will not effect the overall output that much. You might only be able to have a pair of long 85 watt or some 45 watt panels, you will have to search out the size that will fit carefully.
SunElec.com sells larger panels made for house or commercial buildings, with less limited roof space, so are not suitable for your applications.
Besides installing the panel above the A/C will probably reduce the air flow to it by a significant amount, and might lead to hot discharge air re-entering the A/C unit shroud.
The only possible way I can see this working over the top of the A/C is to mount it against the roof in the front, with the remaining part of the panel sitting on the A/C shroud, then find a way to support the back half, so it will sit at least 1/2" above the shroud, not vibrating against it or wearing a hole into the fiberglass. It will act like a wing that will press down, you can deal with that, not as one that will lift up, pulling the screws out of their mounts. However your fuel mileage will suffer a lot, probably more than the fuel savings in not running the generator.
This panel is much smaller, you might be able to fit 3 on your roof, they are about 21" X 26" and only 40 watts each. Keep looking for one about 18" wide to put on the drivers side, perhaps another behind the A?C sideways?
You know, I'm almost considering just taking the AC unit off altogether and putting a cover over the opening.
I mean, my main reason for getting the solar system is so that I can boondock as much as possible, plus I won't even be able to use the AC unless I'm plugged in. Then I'll also have loads of extra space and be able to easily add an additional panel in the future if I need to.
Personally, I would not want to tilt my panels unless I had to. When they are new, and you are all excited about solar, it is great to get up and down on ladders to tilt the panels. It even offers the opportunity to show off your solar, when people see you climbing up and down on the ladder. Then consider the ladder, where are you gonna store it? Now it is time to break camp, the 40 MPH wind did not die down oops. Gee, now it started raining, where is my rain coat? What was that noise, Oh dang, I forgot to lower the panels and I just caught a limb. And the list goes on.
I studied and I read for a couple of years before getting my solar. I was advised by the folks where I bought my panels not to install with tilting frames. They said in the real world, with small systems, mounting the panels flat is just fine. They said they replace many panels on RVs because they were not lowered when breaking camp. Yea right, I made my own tilting mount. After playing with it a couple of times, and really experiencing the loss for a couple of hours, I no longer tilt the panels. I lost an antenna in the trees, no need to loose a solar panel. For me, I learned they were right, no need to tilt the panels.
Personally, I would only mount my solar panels over four inches above the roof, two inches preferred. In the winter months, I would park my RV so the A/C is on the north side of the panel (mounted flat). In the summer months, I doubt the A/C shade would make a real difference. I would leave the ladder at home.
I have had my solar for over six years. I am very pleased with it. I only have 130 watts and a single 100 AH battery. After adding all LED lights, about the only thing I use 12 volt is my TV and Computer, which is less than 20 AH per day. I fire off my Honda 2000 for my A/C or microwave. The solar charges my battery. In over six years, I have used my charger/converter only about 5 times to charge my battery.