I've always liked the idea of solar power
for our trailer, but didn't like the hassle of setting up and placing panels next to my trailer each time, or the worry about them walking off. Big RV units often have them permanently mounted on the roof, so I set out to do just that. I haven't installed the solar
charge controller yet (it arrives tomorrow), but the new installation produces 3 amps of power at 16.8 volts for a total of 50.4 watts under the the noon-day summer sun.
<July 9 Note: Our Sunsei charge controller arrived today and I installed it this evening. The panel generates 1/2 amp at 14V (7 watts) in the late afternoon shade provided by the tree in our front yard.>
First, the solar panel
. I hunted on eBay for a couple months looking for a 50 - 55 watt Siemens solar panel
. I wanted Siemens for two reasons; First they have an excellent reputation for producing power even when the sun is not at an ideal angle and on cloudy days, and second their 50-55 watt panels can be arranged so they're four feet long by just over a foot wide, perfect for fitting between the "hump" that runs down the middle of my trailer and the awning
What I found was a home-made kit panel (assembled from Siemens components) with a wood frame for $260, including shipping. I was a little concerned about ordering over eBay, but the seller had a long history with an excellent reputation with almost all good feedback. (And I always check the most recent feedback comments.)
The wood frame for the panel was in sad shape, but that was OK by me, because the panel worked fine and I planned to build my own frame of 1x4 composite "wood" trim anyway. (Composite wood because it is made for outdoor applications in wet locations, so it won't rot.)
First I made a template of the roof profile where I planned to mount my panel and cut five ribs to match that profile, two end-cap ribs and three middle ribs to support the glass-like structure of the panel so it doesn't crack. Next I cut 4' long side rails so they'd skim about 1/8" above the roof of our trailer, and put a 1/4" deep groove 1/4" down from the top edge of the end-cap ribs and rails for the panel to fit into. I also cut angle pieces to reinforce the corners of the panel sub-structure.
I dry-fit all my bits and pre-drilled the screw holes I needed to hold it all together, pulled it all apart, re-assembled it without the panel, screwed it together and put it up on the roof so I could test-fit it to the trailer and mark the rib locations on my roof, then I spray painted the panel frame with Rustoleum white, took it apart, put marine silicon in the 1/4" deep grooves and re-assembled the complete panel structure using urethane glue at all the joints.
While the glue was curing I drilled the screw mounting holes in the roof: three 1-3/4" stainless steel screws for the front rib and two into the middle and back ribs. When the panel was ready to mount I connected it up to the wiring I had pre-installed using water-tight connectors, put a liberal dollop of marine silicon at each screw hole and held the panel in the right position while Lynne used the drill from the inside to loosely screw the first screw in. Then I did final positioning, loosely screwed the rest of the mounting screws in. Lynne climbed up to the roof and pressed down on the panel frame
over each rib to snug the panel to the roof as the screws were fully tightened.