Adhesive advice for Solar panels

A

Aurelia

New member
I finally did it and found the perfect size panels for our roof. But I had to import them from the UK to avoid paying way too much for them. This is where I plan to put them, one on each side.

http://www.c-brats.com/modules.php?full ... _photo.php

They are a thin flexible panel and the recommended adhesive for roof attachment is generically Sikaflex. There are of course different formulas of that product with this being a common example.

http://www.jamestowndistributors.com/us ... kaflex+291

What type of roof surface prep would you recommend and what type of adhesive solution would you pursue if this was your boat?

I am thinking:

-Clean the roof surface well
-Use a bead of 3M 4000UV or just use 3M VHB double sided tape

Thoughts?

Greg
 
What type of solar panel did you choose? Can you tell us what specific panels you purchased?

Generally I believe that there should be an air gap under the solar cells. Many of the flexible panels are put on Bimini's which allow for air flow under the panel.

The 200 watt single panel I put on the RV, is held in place with SS "Z" brackets with lift the entire rigid panel about 3/4" off the fiberglass roof. The Z brackets are held with SS screws and the bedding is 5200.

One other comment is that it is nice to be able to track the sun, if you at a mooring location--which may increase the efficiency by over 25%. (Full articulation is difficult, but done--and usually it is fixing one side of the bracket, and the allowing the other side to rise, to get as close to 90 degree incident angle with the sun.

If I was flat mounting, on the cabin top--and not going for any gap, I would clean with soap and water, then wipe with alcohol, and use the 3M VHB double stick tape. The thought is, that this is a large surface of the cabin top, and when the panels need to be changed out, it will be easiest to remove. The worry about tape, is that it does allow slight stand off--and thus water, salts, dirt etc can get under the panel, and be difficult to clean, since there is only avery small gap. Also might allow some "pooling" of water in the center of the panel.

If I was going to use a peripheral bead, I would use BoatLife LifeSeal. This is a hybrid single part polyurethane/silicone. It gives excellent adhesion, but does not attack plastics, as many urethanes do. I don't know what the structure of of the support matrix of the solar panel--and how it would react to some sealants such as the 4000 (which I like for many applications).
 
Thanks Bob and I am leaning toward the VHB tape approach. Good points about the gap behind both for cooling and keeping it clean.

These are the panels (using 2) I choose for fitting well on the flat portion of the 19 angler roof and maximizing the power production. I have so much going on with the rest of our roof load that allowing for panel movement to track the sun is just something I decided to forego. We will get what we get with the hope that these panels will help keep our self sufficiency level up with the recently added small freezer. They push a maximum of about 6 amps but if I can get 25-30AH of power from these panels in a day, it would nullify our freezer power use and keep us completely free from shore power as we basically were before the freezer. Even if we only get 10-20ah per day which I think is realistic, it will still extend our power enough to keep our power going for the duration of our boat trips even if we never use a dock.

http://www.photonicuniverse.com/en/cata ... -boat.html

I found this design a few months ago but the US vendors of this design market it for marine use and thus charge about 350 dollars per panel. I did enough digging to find the true producer of the panel then tracked it down under a different name in the UK sold for the caravan market without the yacht markup. So I was able to get two panels shipped to the US for just over 300 US which was less than the cost of one panel in the US.

They are 6v so I am using two wired in series for 12v charging. I tested them last night with a battery and charge controller in partial sun condions and it all checked out just fine. I was a little worried that one panel in the sun and one in the shade would not put out enough voltage to push the charge and I would need a booster for it. But my suspicions about solar panel voltage were true and the panel in the shade still puts out enough voltage to trip the charger even if the amperage coming from the shaded side is very small. I hope to install them in the next week.

Greg
 
If the panels are sized adequately (i.e. large enough), your storage is sufficient, and what your demands are, you may be get all the power you need during the time the sun is mostly overhead (say 10a-3p) without articulating the panels. Depends on your latitude and time of year though.
 
Greg, Thank you for providing the link. You know, but I am not sure that other readers will pick up that these are "6 volt" solar panels, and have to be connected in series to give you the max 5.62 amps (instead of the 100 watts one might expect in parallel circuit.

Peak power: 50W
Maximum power voltage: 8.9V
Maximum power current: 5.62A
Open circuit voltage: 10.4V
Short circuit current: 6.01A
Click to expand...

As per the instructions, either the panels are run in series, to give 12 volts, or you have to use a voltage boosting controller (which curtails loss of amperage).

Using ssobol's 10 to 3 (5 hours) at 80% total output--which I think is being generous, I would expect somewhere in the 22.5 amp hours per day. in ideal conditions. (For example full sun at lake Powell:

If my calculations for Vancouver city (typical of cruising area) on July 1, are correct, maximum incident angle you will see at local solar noon is 64*, 10 AM/2PM is 55* and 9AM/3PM is 42* Lake Powell would have a shorter day, but angles at noon is 78*, 10/2 = 60*, 9/3 = 50*

However, in the PNW, with the % of overcast, I suspect your output will be less. Hopefully you will track the output, (cheap meters on the internet--give voltage and amps in and out) just for the panels.
If the back is Polycarbonate, this may limit what adhesives you can use.

These look like good panels, and I am looking forward to your usual excellent analysis! Interesting that the cells are made in the US, but you can buy them cheaper in the UK!
 
The boost charge controller for using one panel is a little costly for the size so I am not sure why a person would go with that arrangement. I will connect it and monitor through my existing Victron battery monitor so I can track the incoming power.

I really picked these for the dimensions and thin profile. I was relieved to find the less costly version overseas and the company was great to deal with on the order which was by email and paypal.

If anyone is interested, I can send you the email address of the contact at photonic universe who helped me execute this purchase. Shipping was by air and took three days to the west coast.

Because I already have a monitor, I choose to use a very simple charge controller.

http://www.campingworld.com/shopping/it ... -amp/56011

I also bought another 6 dollar simple unit simlar this to experiment with or use as a backup in case of failure during a trip.

http://www.amazon.com/Sun-YOBA-Charge-R ... controller

A friend gave me a 30amp unit to use but it is quite physically large and our boat is quite small so I elected to stay simple.

Greg
 
I don't know the exact details of your panels (and that may make a difference), but I have been running two of the typical "flexible" (which they now call "lightweight" and discourage one from bending) panels for the past year or so. Mine are Grape brand, but they are similar to the Renogy ones. Both of these brand/models have had extensive failures. One thing they found is that attaching them directly to a flat/hard surface didn't give them enough cooling on the back, and apparently this led to some of the failures.

I have had mine on the ground with supports and space beneath them, so I haven't had the overheating problem. I did have one diode box melt (replaced panel under warranty), and one of my original panels has some holes in the top plastic from a very gentle contact (slow motion flop over) onto gravel. They also get very floppy and crackly if you move them when they are hot (I try hard not to). I'll be surprised if I get two years out of them, but I did know that going in.

I originally bought them for the C-Dory, but then found them to be very useful for the RV where I can carry them inside (behind the seat) and then put them out in the sun while I park in the shade.

Given that those advantages wouldn't be really applicable to the boat (there is no shade to park in, and I won't be taking them inside when underway), I decided to keep the "flexible" panels for the RV/ground use, and I mounted two rigid/glass/aluminum panels to the C-Dory. So a total flip around from my first intentions.

Anyway, all that to say that at least the Grape and Renogy flexible panels turned out to have major problems, some apparently exacerbated if they were mounted tight to a roof. Renogy took theirs off the market until they can improve them, and Grape's are off the market as well. I hope they do improve them as they can be really nice for certain situations. I know I would not want to lug two 16#, sharp-cornered panels in and out of my RV. Maybe your panels are are different though if they are a better/different design.
 
Greg
You won't be disappointed with the VHB tape. I mounted the solar panel on our Casita Trailer using 3M VHB with 12#/sq inch strength. after a 2800 mile trip with head winds and driving 75mph it's still there and hasn't move.
attached 2 1x1 aluminum sq tubes with the tape and bolted the panel to the tubes. Didn't want to drill holes in the roof of the egg.
Devon
 
Greg, some of the distributors/manufacturers recommend an airspace under the flexible panels to keep heat down and get better performance. I'm not sure if that will be the case with yours.
 
Greg,

I haven't mounted solar panels, but my hailer horn is mounted with 3M VHB doublestick tape and it has been up there for 6 years and I have some long distance towing at 60-65 mph. I'm not sure if that tape would soften up with the heat, but I would say you would have less air force on the flat panels than I have on that speaker.

January_2010_346.sized.jpg

Harvey
SleepyC :moon
 
Couldn't you have obtained similar panels from Renogy for about the same cost? I have two Renogy 100 watt panels on Daydream and two 100 watt WindyNation panels on the Columbus fiver. Both installations were around $300, including the controller. I also have a Victron battery monitor on Daydream, which gives added peace of mind! These are all hard panels of course, not flexible, but they are permanently mounted and flexible panels would not have given us any advantage. The batteries on Daydream probably need upgrading, but I have two one year old East Penn 190 AH six volt batteries in series on the fiver. We feel very good about our energy self-sufficiency! Look forward to seeing your setup at Friday Harbor!
 
Solar cells are heat sensitive, providing less output as they get hotter. As they operate, they generate heat so they need cooling on the rear side. Power output is calculated with panels at room temperature; as they get hotter the output goes down

Nothing against tape to hold those panels in place, but they don't allow cool air to reach the back side. You might think of standoffs to give panels breathing room and remain cooler. Operating on a level surface with random headings at Gig Harbor's latitude will decrease the output enough.

Boris
 
Pat, Renology didn't have anything in the size I was looking for to maximize the watts on our small skinny slice of roof. Also, I was not looking for the truly flexible folding panel type but the thin semi-flexible variety. I wanted to have a thinner profile against the roof and light enough weight that I could attach them easily without hard fasteners.

This design is only 11 inches wide but 40 long so it rests nicely on the flat side sections of the 19/22 roof while providing more wattage than I could find in a rigid panel for that same space.

The panels I used are backed with a solid plastic material and are only slightly flexible like a sheet of rigid plastic. The tape I used last night for mounting will actually hold the panel off the roof slightly and the thick white insulative backing should help manage the heat somewhat.

A few pics up so far,

http://www.c-brats.com/modules.php?set_ ... _album.php

Greg
 
The panels I used are basically one 12v type 100w cell assembly split longways in half to get two skinny panels.

I could not find an reasonably priced panel of similar dimensions with as many watts of output.

The advantages of this panel type over the rigid type is the ability to fit a curved surface (I did not need), the lower roof profile (I liked) and lower weight (I wanted). A 50W rigid panel typically weighs over 10 lbs and my 50w panels are less than half that weight for both panels.

As of this morning I have the wiring complete and running into the boat. I have a Kayaking trip starting tonight but plan to finish the install next week.

Thanks everyone for your thoughts and ideas.

Greg
 
Greg,
Thanks for the photos and details--looking good and neat!. I want to see the numbers and see how these work for you The only reason I mentioned using a separate monitor, because you will probably get the "net" in / out with the Victron--vs a pure output with the separate cheap monitor. But you could also put a Digital volt meter in series, and get the output, since it will be less than 10 amps.
 
I just installed a flexible solar panel using 4 snads (Google it). Haven't done a photo album yet. The top of the CD 16 has a slight curve, so the thin flexible panel was the way to go. The snads put 1/4 air space under the panel. I was concerned about the panel blowing off, but now having installed it, I don't think I'd even worry when trailering (although I'll probably still remove it.) I found a 50W that fits perfectly on the little bump on the cabin top of the Cruiser. I still need to get my solar controller installed. Too many projects.

I've had the older style floppy flexible solar panel laying on the top of my yurt for over 10 years. Still works great. I had my doubts about "flexible".

I have some of extra"solar panel connectors" that have a gasket in them for exterior connections of panels. Interested? I can bring them to FH.

Mark
 
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