Replacing a solar panel

[Davie B]

My Lite*House came with a 5 watt solar trickle charger mounted on the roof. When I inspected it lately, I realized that it had been hit by something and the glass broken. I'm assuming that it's toast and have purchased a replacement (On sale for $50 at Lowes).

That brings up mounting. The OEM panel appears to be glued to the top of the trailer with some sort of black stuff. Drilling holes in the top of the camper is against my religion but I'm open to suggestions. Any advice on how I should mount the new panel?

[cpaharley2008]

why not attach the new one to the old one somehow since it appears to be securely attached. may make it easy

[Davie B]

I had a similar thought but realized that I face the same problem. I need to affix it to the old panel which has a slightly different footprint than the new one. I think that scraping the old one off, cleaning the fiberglass top and gluing on a new one is the best idea. I just need to find out what kind of glue to use. I'm assuming that there is a space age invention that is the cat's a** for this application.

[HerseyBA]

Here is a link to a thread using 3M VHB tape to mount a solar panel. It has worked well.
Solar install with VHB tape - The Casita Club Forums

This may give you some ideas. Good luck

[peterh]

Just a quick note while I'm really, really, really supposed to be working on something else (I haven't been around here much due to my workload), but I thought I'd better mention something about circulation.

Solar panel efficiency drops off as the temperature of the panel goes up. To help keep the panel temperature down you need to have a slight tilt on the panel and an air gap so cool air can enter on the panel's low side and exit on the panel's high side. Mounting the panel without an air gap will both reduce the amount of electricity the panel makes on a hot day and can shorten the panel life.

[Davie B]

That would mean poking holes in the roof; something I hesitate doing. But, I guess it's probably the best idea. I know that pop rivets are the device-o-choice for connecting things to the shell of an egg. I'm thinking of long nose rivets with a stack of washers or a spacer between the panel and the shell. Am I on the right track?

[cpaharley2008]

I think they mean air space under the panel, did you look at the Casita installation mentioned above, they have several inches of space, Can you raise the panel any using some aluminum and attach to the old panel which I assume is flat on your roof. A couple of washers may not be adequate.

[Davie B]

The old panel appears to be glued down. It's a plastic frame around a bunch of broken glass that was once a solar panel. How would I attach anything to that? Glue on a frame made of aluminum square tube to the old panel and rivet the new panel to the to the frame?

[cpaharley2008]

The person above swears by the VHB tape so yes, rivet your panel to some trim for elevation and then tape it to the old panel. you may even be able to run your frame across the old panel to get more surface area for the tape to work. take pictures and post please

[peterh]

My philosophy when I installed my solar panels was to cut contoured composite wood trim ribs that matched the roof profile of my trailer and use those as a base for a support frame for my panel (see picture), which I attached to my trailer roof by applying butyl tape to the rib, then screwing through the shell from the inside and into pilot holes the rib. It forms a nice, tight seal that'll last for years. Decades, even.

I do not believe VHB tape will stick to wood or composite wood products, by the way.

[HerseyBA]

If you check the 3M VHB tape site you will find all kinds of products and what materials and applications they are recommended for. McMaster-Carr carries a good selection of the 3M products.

3M United States: 3M

I use the "belt and suspenders" approach and use both tape and mechanical fastners.

[Davie B]

On closer inspection, the old panel was indeed affixed to the roof using some sort of tape. I found the VHB tape at the local big box store and mounted the new to the old. It wasn't an exact fit, but close enough and there appears to be plenty of purchase. I didn't leave an air gap but this is just a trickle charger. I have a volt meter in the circuit and will be paying attention to how it performs over time. When I add some serious PV panels (I'm thinking 65 watts or so), I'll figure out a way to tilt and ventilate them. I pulled the trailer at speed down I-10. The installation seems stable.

The new double battery system performed well. During a 4 night dry stay at MagFest (roots music festival on the Suwannee River), we had lights, fan and all the water we wanted to pump without problems. I still need to come up with a circuit for isolating the two batteries during charging.

Anyhow, thanks for the pointers on tape which I used and the pointers on ventilation which I'll use in the future.

Davie

[Bill K]

A battery switch ( which are used in boats ) have 4 positions.
Off
1
2
Both

That seems like it would do what you want if wired correctly.

Bill K

Originally Posted by Davie B

The new double battery system performed well. During a 4 night dry stay at MagFest (roots music festival on the Suwannee River), we had lights, fan and all the water we wanted to pump without problems. I still need to come up with a circuit for isolating the two batteries during charging.
Davie

[Davie B]

Originally Posted by Bill K

A battery switch ( which are used in boats ) have 4 positions.
Off
1
2
Both

That seems like it would do what you want if wired correctly.

Bill K

Thanks Bill - I'm thinking more along the lines of a circuit that charges each battery independently while providing power from both at the same time. Switches are good (I used to have that on my boat) but automagic is better.