Mounting Safely

[Rucker]

Currently have a 200W on my RV and after visibly seeing the difference in charging compared to a smaller solar panel which the owner was able to move and aim in direction of the sun I've decide to not have my next solar panels laid down flat across the roof simply because they're not efficient when the sun is less prevalent during winter months.

Been living in my RV since Sept 2019 so I've had lots of opportunity to experiment with solar charging and having the ability to angle the panels is crucial during winter months if not then adding more panels is the only way to get the same charge. So in order to save money, time, effort and most likely headaches it makes more sense to have less panels and smaller panels which I can direct towards the sun.

The other big benefit is that sometimes the RV lot I was parked at for the weekend only provided sun in the morning and/or late afternoon for a few hours so again I'm left with batteries only partially charged however if I were able to angle the panels they would have easily fully charged the batteries in that limited time.

something to think about IMO

Here's something I posted a few years ago about 'tilt-a-whirl' solar panels:

"A quick Google search of 'how much solar do you lose when panels are flat' return all kinds of discussion on the topic, including a bunch of design considerations I hadn't thought of, like,
-some solar panels will need an extra frame because they are not rigid
-on fixed arrays, like on a house, wind forces must be factored in. What if you forget to lower the panels and drive away?
-tilted panels are easier to wash
-tilted panels allow better air circulation underneath and can aid in cooling

Another factor is orientation. If your panels only tilt up on one axis your rig's orientation to the sun will also be a factor in solar output.

On to the actual difference in output. One handy site showed solar panel output data from Phoenix's Sky Harbor Airport (Arizona) as a function of panel tilt and orientation. Output was optimal at 32 degrees of tilt, pointed south, but only dropped by 15% if flat. Other sites suggest 10 to 20 percent efficiency losses with panels flat on the roof depending on the location. The further north you travel, the greater the loss.

Assuming the larger losses and an average solar array of 1000 kW you can safely make up the difference in efficiency loss placing panels flat by adding 25%. At a dollar a kilowatt we can now say the 'value' of an optimally tilted and oriented solar array compared to one that is flat is about two hundred and fifty bucks."

Point being, tilted panels adding significant charging power may not be a foregone conclusion. Lots of work for what gain? Answer that question, and you'll be golden.

 

[Crlefley]

I have 2kW of tiltable panels hinged to a central walkway, with four panels each side. The walkway runs between the two roof hatches, and is through-bolted to the roof ribs every 19" with 3/8" stainless bolts and nylok nuts, with cross-bracing to eliminate any potential sideways or longitudinal movement. Each panel sits inside a separate support frame to lessen the stress on the panel's own frame, and each support frame is hinged to the walkway with multiple 1/4" SS bolts and nylok nuts. The outer edge of each panel is located onto a continuous 25' length of 6061 angle that's through- bolted to each roof rib with 5/16" SS bolts and nylok nuts. I would consider this as the absolute minimum of security and attachment strength; I've joked when saying my bus could be lifted by its panels, but that's not far off the truth.

For everyone else's sake do NOT glue PV panels to the roof of a vehicle that can experience wind speeds as high as a hurricane's. How would you explain to a judge and jury why you thought that sticky tape was better than any other method? Please get real. If you can't be bothered to do it right, don't do it at all.

John

John, Do you have any photos of this setup? Im assuming your panels/framing are mounted the "long way" along the roof. 250watt panels? I have thought about this scenario exactly. Im very interested in how you setup the hinged system. I am currently racking my brain on doing something similar. Thanks for your time!

 

[Conversion Noob]

That's not the same because it's only one axis moving, where my friend can easily adjust the panel both up & down and move very 4 hours to maximize the output.

 

[Iceni John]

John, Do you have any photos of this setup? Im assuming your panels/framing are mounted the "long way" along the roof. 250watt panels? I have thought about this scenario exactly. Im very interested in how you setup the hinged system. I am currently racking my brain on doing something similar. Thanks for your time!

Sorry, I don't take photos! Here's a short video of some of us Crown Coach Junkies leaving Buses Gone Wild VII for some hooning around in town , and my bus is the third. I had made the panels' support frames, but not yet installed the panels themselves.

If I park the bus pointing due east or west, in winter I can raise the far-side panels to 21, 33 or 45 degrees up to maximize solar harvest, while the near-side panels remain stowed down against the roof at 21 degrees down. It's not quite as efficient as having a multi-axis tracker, but they're A LOT of work to build on a vehicle for what may be relatively little gain over my much simpler approach. Even my setup is still far better than just laying panels flat: unless you live between the Tropics of Cancer and Capricorn, flat panels won't help you much...

Another consideration which I've never seen addressed is cleaning the panels: only a few leaves can substantially reduce a panel's output, and bird poop or dust can cause a noticeable drop in output. Instead of teetering precariously on a ladder with a hose or heavy buckets of water, I just climb up through the front roof hatch onto the walkway, then plug in my washdown brush's short curly hose into the two quick-connect water outlets under the walkway. That way it's completely safe, and I don't get soaked by all the dirty water sluicing back down onto me. Easy! I'm even thinking of a possible high-pressure water spray system for each panel, then all I need to do is flip a switch inside to wash them. Easier!

John