Solar panel install concern

[dave10a]

I am presently considering hooking up solar panels that I removed from my past motorhome. Since I do mostly "snow bird" in the South and store the trailer when not using it I would like to get the most out of my panels (two 100 watt). The panels would be backup where there is no power, keep the batteries charged and I would like to install a grid tied inverter along with a 3kw inverter so I can pump power from the panels to the RV park that charges for power while snow birding. My concerns are mounting the panels on the roof. The roof is sturdy enough to walk on but I am not sure how much material there is under the rubber and will lag screws really hold the panels on with strong wind while traveling or stationary. I know many 5th wheels have panels, but I am not sure how they are mounted and how secure they are.

 

[SmokeyBare]

I used aluminum angle to build my brackets.
I used too Well-Nuts for each bracket.
Under and around each bracket I also used plenty of Self Leveling Rubber Roof Caulking.
I mounted 2 panels on a aluminum angle frame that attached to those 4 aluminum angle brackets
Brackets were made with a taper so they wouldn't bind. I could loosen the bolts on one side and elevate the panels.

A Well Nut is a sleeve of Rubber which expands when the nut located in the bottom is tightened... squeezing or expanding the Rubber Barrel tightly in the hole.

 

[dave10a]

thanks for the reply. I think your suggestion will work. I will give that a try and experiment on a sheet of ply the same thickness as my roof to make certain it will hold the force before I mount them on the roof. I run the wiring and installed the batteries, inverter and grid tied inverter with appropriate switching and hope to have this completely installed tomorrow. At first I was thinking to not install the solar panels and making them portable, but after thinking about security and safety I will install them on the roof if the bracket pass test... Anyway thanks again for the input.

 

[dave10a]

Tested rubber well nuts on plywood sheeting the thickness I believe Heartland uses on my Landmark and the panel did not adhere like I wanted. I am now trying to get roof information from Heartland so I can hopefully find rafters to lag bolt my mounts. I would feel safer while driving at a max 75mph with a 40 mph head wind. That gives a hurricane force wind on the panel; and is a realistic wind force that my trailer could experience while driving in various areas of the US. The rubber well nuts will not hold up to those forces with that scenario.

 

[crazybanshee]

Dave I just used small lag screws into the plywood and they have been up there for five years without a problem. Used sealant under the bracket and over the screw head. None of my five panels have moved and I drive 75 into high headwinds all the time

 

[dave10a]

Dave I just used small lag screws into the plywood

How thick is the plywood on your roof. I think mine is 1/8 which is not enough to hold lag bolts with confidence. The motor home that I previously had was 1/2 under a fiberglass roof which held with 4 lag bolts with confidence. I think I need to bolt to rafters if the roof plywood is only 1/8 using unistrut if the rafters are not on 16 inch centers.

 

[crazybanshee]

If your plywood is only 1/8" you would fall through. Mine is 3/8" or 1/2". All my friends just screwed into the plywood also. No need to over engineer.
Doug

 

[dave10a]

If your plywood is only 1/8" you would fall through. Mine is 3/8" or 1/2". All my friends just screwed into the plywood also. No need to over engineer.
Doug

I am trying to get confirmation from Heartland as the thickness. According to the sales stuff, Heartland uses a core foam technology that allows strength with thin sheeting like 1/8 inch. I am not trying to over-engineer, but simply trying to determine how the roof is designed and built so I can decide how to install the panel safely.

 

[Silverado23]

You may be able to determine the thickness of your roof by removing the interior trim around one of your roof vents.

 

[danemayer]

I am trying to get confirmation from Heartland as the thickness. According to the sales stuff, Heartland uses a core foam technology that allows strength with thin sheeting like 1/8 inch. I am not trying to over-engineer, but simply trying to determine how the roof is designed and built so I can decide how to install the panel safely.

I read the sales stuff the same way; that there's a thin veneer between the rubber roof and foam. Laminating it all together with the foam and aluminum structural support is probably where the strength comes from.

Maybe you should ask about the aluminum specs to see if maybe they're strong enough to anchor your panels. Not sure how you'd locate them, but maybe there's a way.

 

[sundancer87]

I think I would find out how many RV parks will allow you to sell them electricity before I went to far with this project. Not every electric company buys back consumer electricity.

Another question that I have is, do you really think 200 watts of electricity produced by your panels will be enough to power your appliances and have some left over to sell back?

The intertie inverter will be costly and will have a long ROI even if the RV park and the electric company will buy your electricity. Then there's the issue of finding a metered RV spot for your plan.

It sounds good on paper but I think you'll find your 200 watts will be used and nothing left over.

 

[dave10a]

I read the sales stuff the same way; that there's a thin veneer between the rubber roof and foam. Laminating it all together with the foam and aluminum structural support is probably where the strength comes from.

Maybe you should ask about the aluminum specs to see if maybe they're strong enough to anchor your panels. Not sure how you'd locate them, but maybe there's a way.

I stud finder should locate the aluminum rafters.

 

[dave10a]

I think I would find out how many RV parks will allow you to sell them electricity before I went to far with this project. Not every electric company buys back consumer electricity.

Another question that I have is, do you really think 200 watts of electricity produced by your panels will be enough to power your appliances and have some left over to sell back?

The intertie inverter will be costly and will have a long ROI even if the RV park and the electric company will buy your electricity. Then there's the issue of finding a metered RV spot for your plan.

It sounds good on paper but I think you'll find your 200 watts will be used and nothing left over.

I am not looking to sell power back-- only to allow my panels to do something rather than nothing by slowing down the meter . My micro-grid tied inverter should save me up to 0.2kw/hr which adds up over a month. My power bills at the RV resort average $100/mo and if I can save $5-$10/mo, that is better than nothing-- at least the solar panels are doing something besides sitting on the roof doing nothing.

 

[sundancer87]

If you aren't interested in selling back power and only interested in reducing your RV park power bill what do you need a grid tied inverter? Wouldn't it be simple enough to run a few applicances off a battery bank and through a normal inverter without being tied to the grid?

If your panels are producing electricity they are doing something, hopefully charging batteries so you can use the solar power instead of grid power.

I see a lot of comments about solar systems and RVs and it seems to me that a lot of owners overthink the process. One guy wants to put a transfer switch so when he goes to grid from inverter he doesn't put reverse voltage to his solar controller. That won't happen if everything is connected correctly.
You want to use some panels to make electricity to trim your power bill there at the park, that's good but I don't see the need to be tied into the grid with an intertie inverter that may cost you 2 thousand bucks.

 

[watchthebox]

Tested rubber well nuts on plywood sheeting the thickness I believe Heartland uses on my Landmark and the panel did not adhere like I wanted. I am now trying to get roof information from Heartland so I can hopefully find rafters to lag bolt my mounts. I would feel safer while driving at a max 75mph with a 40 mph head wind. That gives a hurricane force wind on the panel; and is a realistic wind force that my trailer could experience while driving in various areas of the US. The rubber well nuts will not hold up to those forces with that scenario.

I'm surprised to hear your tests with Well Nuts didn't work out. I've found Well Nuts to be ideal for mounting solar panels on my 5th wheel. I feel much more confident with Well Nuts than I would be with just screws into plywood.

In your test, what size (length and diameter) Well Nut did you use and in what thickness of plywood? And what size hole did you drill in which to insert the Well Nut? I don't recall exactly, but I think I used 7/8 inch length by around 3/8 inch in diameter Well Nuts with 10-32 bolts. I believe that the plywood on my Cyclone is 3/8 inch thick. I didn't actually try, but I really doubt I could have pull one out after installation if I had tried. Here's a site with specifications of Well Nuts: http://www.thread-rite.com/pop_blind_rivet_nuts/well_nut_inch_threaded_inserts.htm. If I'm reading the chart right (I believe I have the H1032 type Well Nut), they have a tested installed tensile strength of 260 lbs. I put two at the corner of each panel, so it would theoretically take 520 lbs. to lift each corner, right? If that much force is acting on my 5th wheel, then I probably have bigger things to worry about!

 

[dave10a]

I don't see the need to be tied into the grid with an intertie inverter that may cost you 2 thousand bucks.

The micro inverters cost about $150. I have one left over that I used to evaluate a solar energy for a project I consulted with last year. So I am simply using hardware that I already have to get the most out of it rather than letting is sit and collect dust. Is it economical to buy the hardware and do what I want? the answer is no. Pay back on solar energy is not there as demonstrated by the Solar companies that are going out of business. Solar for RV make sense for remote areas and that is about it. Some day in the far future when solar panels can respond to more the 30% of the light spectrum to become 70% or better, then solar will make economic sense to replace other forms of energy.

 

[sundancer87]

I think when the oil companies get out of the business of holding the solar market back we'll see more arrays all over the place. Until then the idea will never be as great as it can be.

My panels have surpassed the 12 year warranty by another 8 years, my analog controller is still working like it did 20 years ago, the only thing I have in my house that doesn't like the modified sine wave is a cheap mirco wave that I use twice a year.
I have finally made my initial costs back so I'm not only producing electricity each day, I'm making gravy too.

Good luck with your project, I hope the effort is worth the return.

 

[dave10a]

I think when the oil companies get out of the business of holding the solar market back we'll see more arrays all over the place.

Well, I don't agree--- The technology and manufacturing process is not where it would make Solar panels economical as compared with oil, coal, natural gas or nuclear. Yes Oil companies are engaged in Solar energy, because they are in the energy business and are simply diversifying. Not trying to sound political, but simply stating the facts as I see and experience them.... BTY the way you can make you modified sine wave inverter work to produce a sine wave with a transformer and a capacitor, but by the time you buy the transformer and capacitor your might as well buy a sine wave inverter. Transformers to handle 2 kw cost $100 plus and the capacitor would be an additional $20 plus....

 

[dave10a]

Thanks to Heartlands response to my request for roof information, I can now proceed to install the solar panels with confidence. The roof material is 5.2 Luan and therefore it is NOT safe to attach the panels using screws or well nuts. It is only safe IMHO if you attach directly to the rafters or framing at the edge of the roof. Therefore unistrut is not over-design, but the safe thing to do...... besides it is not that hard to properly install.

 

[Fergizmo]

Thanks for your posting. That is some good information to know before I get started installing mine.