Adding Solar Panel

[bonnie]

I thought I posted this today, but it doesn't show. I am getting ready to retire and want to travel and see this great country. I need solar to generate power when I'm not in a park. After a bit of digging I settled on a Renology 150 watt panel. It will charge two 35ah wheelchair batteries which will be wired to make 70ah. I would like to mount the panel on the back of the roof on the angle. It will cover most of the old/new additon. I am trying to work out attachment. Will I need more than hard points embedded in the foam? I could build and position braces of 2x2 to give it more strength. Since it will be riding at an angle, would I need to somehow protect it from windshear?

[GPW]

Good questions .... We must defer to those with more Solar experience ... But hard points can easily be added as you need them ...
Bonnie , I’d like to get into more Solar too .... we only have the HF panels , bought long ago ( on sale) But we see the new technology is really much more efficient , lighter , and better suited for camper use than the old stuff ...

Ps. On the road , I don’t think you’d want to mount it so the air stream can get underneath , lifting it and possibly rip it off the mounts ... Maybe a small Foamie “Air Dam” In front of it ( Just a drip edge mounted sideways ) might help at highway speeds...

[lrrowe]

While not for this project, I had too thought of a air "dam" in front of my future panels. I have not seen it being done by anyone on this forum, I do not know why it would not be a good idea.

[GPW]

Rowe, "I have not seen it being done by anyone on this forum” ... It’s as somebody around here said ... “ if everybody is thinking the same thing , then somebody is Not thinking “ ... Innovations meet Dogma in endless disagreement ...

As an old airplane guy , the easy way to block the flow of air against something is to put something else in front of it ... (logical !)

[bonnie]

Glenn you made me laugh.

I found these: http://www.amazon.com/Solar-Universal-4-corner-Drill-free-Installations/dp/B00ZAW18AY/ref=pd_sim_sbs_86_1?ie=UTF8&dpID=31XGIiDUF-L&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=1DTG41NDE3QHPCH3MZ76

They look viable for my application. Especially since I can get singles to add to the sides. There's also a cable inlet that is waterproof. $$$ but probably worth it in the long run. I'm thinking a hard point inside made like an H but with a block of wood the size of the mount. The wings would help distribute the stress, don't you think?

[GPW]

Gosh , I don’t know about that ... They do look good eh ? I just got a crazy thought of long nylon bolts and big Fender washers as a mechanical fastener through the roof ... With Foam’s great compression strength and the ability to be plugged up again should you decide to change , seems a shame to put a piece of wood in there , as we’ve been trying to get away from using wood ... Bolts and washers would be barely visible inside the cabin and could be painted to match ... Outside wouldn’t depend on just adhesive alone to retain precious solar panel ...

[Shadow Catcher]

I tracked down the Chinese manufacturers before these mounts were being imported into the US and have been using them for 6+ years (meaning I do not remember exactly how long). They are attached with 3M VHB tape. I called 3M and spoke with one of their engineers for better than 45 minutes and give him the dimensions of the panel (Large) and he did the wind load calculations and told me how many square inches I needed for it not to be come a very expensive flying missile. The mounts are ABS plastic and hollow so there is limited area. With the two long mounts I was able to have sufficient area with a margin for error.
If you use 3M VHB tape surface prep is critical and you MUST have enough surface area. The flanges are wide enough for bolts. I drilled and tapped holes through the mounts and into the panel.

[Gettin Started]

I don't know what foam you're talking about, but 3M VHB tape or 3M marine adhesive/sealant 5200 (found it at my Home Depot) are ways to permanently adhere solar panel mounts to a roof without penetrating with bolts.

[peeler]

theres a seller on ebay named 'propowerbatteries' - http://www.ebay.com/usr/propowerbatteries? that Ive bought batteries from a few times now, if you end up needing more and looking for a deal. a couple thoughts on the solar, the faster you draw on your battery reserve, the less total amp hours they will give up. meaning, the total useable capacity decreases with increased load. another thing i try not to do is drain any of my batteries down below 40 percent charge. i set stuff up to shut down to prevent complete discharge. so it is good to factor in extra storage if you haven't. ive had good luck with the glass mat AGM / Sealed Lead Acid batteries both for solar as well as one electrical vehicle. Anyhow I'm probably being quite general with my comments but that's okay theres lots of technically inclined folks around (op you may be one of them) and so I just wanted to add in a couple things that can be overlooked on a first time setup. not to get into controllers and inverters and all that, just the basic... if you got 100AH of storage on a 12 volt system, figuring half that usable meas 50AH, and then, out of that 50AH, there's a lesser number that is the actual amount of AH the batteries will give you before they're half discharged, less than 50AH, the harder the draw, the smaller the total available output. I don't recall the exact math on it. But good ideas to add to your thoughts if not already there. cheers op, hope you have fun travels!

*also useable power drops with temp of batteries. i think a battery around 32F will give up somewhere around half the power of a battery at 80F. Food for thought

[ghcoe]

Just a note. It is better to be able to set up the solar panels separate from the trailer and attach to trailer with power cord. That way you can position the panels to the optimum angle to the sun. Plus if you park your trailer in the shade to keep cool your panels cannot perform well on the roof. With a power cord the trailer can be in the shade and your solar panels can be out in the sun working for you.

[bonnie]

I don't know what foam you're talking about, but 3M VHB tape or 3M marine adhesive/sealant 5200 (found it at my Home Depot) are ways to permanently adhere solar panel mounts to a roof without penetrating with bolts.

Getting Started, my foamie has no wood in the roof at all, so the solar would mount directly to canvas covered foam.

[bonnie]

Gosh , I don’t know about that ... They do look good eh ? I just got a crazy thought of long nylon bolts and big Fender washers as a mechanical fastener through the roof ... With Foam’s great compression strength and the ability to be plugged up again should you decide to change , seems a shame to put a piece of wood in there , as we’ve been trying to get away from using wood ... Bolts and washers would be barely visible inside the cabin and could be painted to match ... Outside wouldn’t depend on just adhesive alone to retain precious solar panel ...

That's an idea. I like it.

[bonnie]

I tracked down the Chinese manufacturers before these mounts were being imported into the US and have been using them for 6+ years (meaning I do not remember exactly how long). They are attached with 3M VHB tape. I called 3M and spoke with one of their engineers for better than 45 minutes and give him the dimensions of the panel (Large) and he did the wind load calculations and told me how many square inches I needed for it not to be come a very expensive flying missile. The mounts are ABS plastic and hollow so there is limited area. With the two long mounts I was able to have sufficient area with a margin for error.
If you use 3M VHB tape surface prep is critical and you MUST have enough surface area. The flanges are wide enough for bolts. I drilled and tapped holes through the mounts and into the panel.

My panel is 40 x 43, I believe. Did you use just one set of the longer mounts? Are they 20"?

[Shadow Catcher]

I have a portable panel I have yet to use. A higher voltage panel can use even shade.

[GPW]

Bonnie , the only problem I see gluing directly to the roof is , you’re just gluing it to a layer of paint , or even light canvas underneath ( we know how easily we can tear the canvas away from the foam , sorta' like a hole in your sock ... Being somewhat familiar with your camper ... It might be prudent to put just the mounts on the roof and make the solar panel removable so you can put it out on a sunny day , or move it elsewhere to get more Sun , or even just pop it off the roof for travel and put it inside ( you can easily sew up an old blanket as a “cozy” for it) ... Also , when not camping , you can use it for everyday power , for those small things that are always sipping your power ... With a 25 year average life span , I myself (being Old ) would want to use it as much as possible ...

Which reminds me I need to really do SOMETHING with those HF solar panels we bought many years ago .... They don’t do a thing still sitting in the box ...