Mounting Flexible Solar Panels on a Van

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I’ve installed my massive solar array. I have 10 flexible panels at 100 watts each for a total of 1000 watts. I purchased them here. They changed their website and you must request a catalog now. Why do I have a huge solar array? Because I’m doing an all electric van conversion and I will be able to run an air conditioner for a few hours per day.

Since I knew they would overhang slightly, I was originally going to put them on a roof rack. That option proved to be too expensive. So instead I decided to mount them with VHB tape directly on the roof. I was skeptical of using tape to mount solar panels at first. Then I watched this video and did a little more research.

I purchased 5 yards of a model specifically for painted metal and plastic adhesion from amazon. I can say first hand that this tape is as strong as they say when it is used on metal and plastic. 3M makes a few other versions for different surfaces. Amazon Link: 3M 4941 VHB Double-Sided Acrylic Foam Tape, 45 mil, 0.5″ x 5 Yards (Dark Grey)

I had to lay out the panels on the floor and decide where the wires would go, and where the tape would go. I overlapped the panels at the edges to save room.

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Substrate preparation is the key to good adhesion. I followed the steps in the video below, but I added some of my own. After the alcohol, I used a heat gun on the van with the low setting. Just enough to evaporate any water content left over from the alcohol. Adding heat also helps the bond form. Then I put a weight on the tape for a few minutes.

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Over the VHB tape, I applied painters tape to prevent the wax paper from coming off while I worked on the roof.

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For each panel, I had a wire orientation plan.

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After placing the wires where I wanted them. I prepared the back of the panels for the VHB tape. The only difference was that I used sand paper to score the back instead of the scrubber.

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I pressed down firmly in each tape location for about two minutes. Then I put a shoebox with water bottles on top to maintain constant downward force for about 5-10 minutes. The towel was to avoid scratching the panels. I had to learn that the hard way with the first panel. By the 10th panel, I felt like a pro.

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I’m not going to discuss the circuit diagrams here. I’ll have a whole blog post about wiring the entire van. I just want to show what I physically did with the four leads going into the van. I basically cut off the MC4 connector and butt spliced with a water proof shrink wrap splicer. I picked them up at home depot along with the wire.

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Drilled a hole behind the fan for wire entry. Then inserted a grommet that I could fit four wires through.

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Poked a hole in the reflectix.

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This is called a cable feed gland. It’s designed for a single larger wire, but I used it for four #12 wires. It was still able to seal around the wires tight enough to prevent leaks. To mount it, I used some leftover VHB tape. Amazon link: Instapark® IN-SW Surface-mountable Single Cable Feed-thru Gland with Adjustable Grommet & Blanking Plug, Color White

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I used dicor to seal it. I had some leftover from the fan installation. When using it to create a seal at a 90 degree angle, I had to place it a little higher than where I wanted it to be because it well lower over time until it cures. It made a great seal and I haven’t had any leaks. Amazon Link: Dicor EPDM Rubber Roof Lap Sealant, 10.3 oz, White 501LSW-1

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When it is tightened, it squeezes the wires with rubber to create a water tight seal.

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So the solar panels hang over a little bit. Does it take away from the stealth? I can’t decide. I wish the sprinter roof didn’t taper in so much.

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There were some sacrifices I made to fit 1000 watts on my roof:

  1. I can’t access the wires or their connections underneath the panels.
  2. If I need to replace a panel, it will be hard to get the VHB tape off.

With that being said, I’m happy about the following;

  1. It is somewhat stealth
  2. I have hella power
  3. It doesn’t add much weight

I’m still on schedule to leave at the end of the month. I have finished the kitchen, but I haven’t written that post yet. I just sat down for a minute between working in the garage to type this one out. My plan has changed slightly. When I leave, I think I’ll just take a short trip to NJ and back for about 2-3 days. This will allow me to work out any kinks in the van when I get back to the garage. I have the garage for another 30 days, but I definitely won’t stay in PA that long. I just need about a week to tie up some logistical loose ends and say goodbye to some friends before I leave permanently. Today I’m finishing the ceiling and the next two days I will build the closet structure.

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UPDATE 07MAR2016:

Here’s a shot of the van from far away with the solar panels on top. I think it still looks pretty stealthy.

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I’ve been getting some feedback from the sprinter-source.com forum about VHB tape and sprinters. Apparently, the tape works great, but the paint bond on the sprinter fails sometimes. I will keep an eye on the solar panels. If I see the paint start to come up, I will use rivets to keep the panels in place. If it fails, It won’t be at all 40  pieces of tape at once. Rather, I think it’ll be gradual with couple spots failing first. So I’m not too worried about the whole solar array flying off while driving.

UPDATE 12/19/2016: I’ve replaced these panels. See the post about the new solar panels.

Disclosure: This post contains Amazon affiliate Links. HurriedYear.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

  • Jon

    Hey, I’m wondering how many panels would you have fit if you had put them one perpendicular to the van and the other parallel. I’m thinking of doing 1kw but on a ram pro master.

    One thing might do, is a DIY custom panel. That way I can make longer but narrower panels. I have not seen a DIY for flexible panels though, only for glass ones.

    Let me know what are your thoughts

    • Joe

      I played around with that layout, and many others in sketches. It was the same amount that way. I have actually seen DIY flexible panels before. I considered them for a while, but it seemed like a ton of work for something that was very experimental. I’ve seen narrower flexible panels before too. If I ever replace these, I might go the route of getting narrower panels. Hopefully by then, higher wattage/area panels will be available to consumers.

      • SkOrPn

        If I may ask, what is the exact width and length of your vans roof? Is it the 177 wb model with high roof? I can’t seem to find the dimensions of the roof top, and I need that info to plan my solar panel setup.

        • Joe

          Nah i have the 158wb with high roof. it’s probably the same width as mine. I can’t find the exact measurements, but I’m pretty sure it’s close to 156 cm wide at the very top.

          • SkOrPn

            Thank you Joe. I noticed SolarCity has these low profile black rimmed panels that are like 350 watts each and high quality Panasonic tech. I was thinking maybe use those, installing three corner models of them for 1050 Watts. With the slanted sleek black corners it would make it harder for thieves to recognize them as solar panels.

  • Matthew Pease

    i too am in a camper, though with just 500 watts on the roof. What the heck are you oging to use all that power for? I guess a compressor fridge, but do get a very quiet one. You could also use excess power each day to heat up some water. (just a resistive coil in some water I think)

    if you really want to store some of that power to keep it around for a few dark cloudy days, then you might consider forking some cash for a lithium ion battery set up. Though maybe you already have your battery.

    I bought a 60ah battery & it isn’t nearly enough for these 500W of panels. It fills up most days before 11. And that is with 2 of us using computers & lights. fridge & water heater on propane.

    anyhow electrodacus makes awesome lithium ion battery controllers. I have his first design which works flawlessly. his newer setups are for larger rigs. you could fork the cash & then some day when you move to a cabin / house you could just move the rig over to the house.

    nice thing about the li-ion are: no hydrogen off gas, use as much power as you want without effecting the batter efficiency, use about 90% of the battery capacity regularly, and so that makes it way lighter, and it’ll go for thousands of cycles. at least 10 years.

    cheers

    • Joe

      Thanks for the comment. I have such a large solar array because I use it to run an Air conditioner, induction cooktop, and a small ceramic heater. Maybe when my AGM batteries need to be replaced, lithium ion batteries will be more affordable. I did consider doing the resistive coil option for a while, but opted against it. I haven’t lived with hot water in such a long time that I felt like it wasn’t really necessary.

      • Matthew Pease

        AGM batteries. It’s a 12V system? How many Ah are those AGMs? Because if they aren’t big enough.. you could actually be pumping the power into them too fast. Not sure what is ideal for lead acid batteries.. That’s the C number and you want it to be kind of low. A/C & cooking. That is pretty amazing. Must be a big battery. What about your fridge?

        I have those same panels, btw. I found that if I lift up them from the center a little.. use some thin foam — the foam they shipped with is good just tape that foam in the center of the panel.. and then pull down the edges to your sure-lok.. then the panels will be a little bent and so won’t collect the water. This way you avoid having to clean them as often.

        • Blue_Oak

          A proper charge controller like Joe has will baby the charge process for the AGM batteries. The bigger concern with them is drawing them down too far.

          • Matthew Pease

            I think that a controller serves more as a gatekeeper. The current flows to the battery, or not. It “babies” the batteries by switching them off / pulsing the charge when the voltage reaches a certain amount. However, if there is too much current coming into a lead acid/AGM I think you can wear it out too fast. Also lead acid batteries become more lossy with higher currents.

            I could be totally wrong though. I know this is the case with lithium ion chemistry, but not sure about lead acid (AGM).

            Well I guess time will tell for Joe’s battery.

          • Blue_Oak

            The word “charge” in charge controller betrays its function. A $550 charge controller will not abuse batteries unless it is broken.

          • Joe

            From my research, the max recommend charging rate for agm batteries is amphours/3.

  • Joseph M

    I am in a shuttle bus and I install 4 600 watts uni-flex solar on my bus 6 years ago and they work very well I get 4,400 watts out of them I also use a TrakMax 30L charge controller with remote meter and I also have 6 200ah battery’s with a 10,000 watt inverter the point of this is my bus is all electric there’s no propane

    • Joe

      Glad to hear it. I like all electric builds.

      • Joseph M

        Thanks I also like all electric build its a lot more safer till this day I still boondock in my bus and no one knows I’m living in it and I have all the admitty of and RV but you can’t tell from the outside

        • Wijnand Karsens

          hey Joseph, what kind of bus do you have? I didn’t know there was a all electric bus on the market yet… I want the same!

  • VeganAria

    Has anyone had a problem due to using the flexible panels? Are they wearing as well as you had hoped? I have (glass) solar on my home and they get so messy from pollen that it seems a plastic is just not going to hold up over the long haul.

    • Joe

      Mine don’t really get messy from the pollen. I do think glass would probably last longer though. I’m still in the early stages right now so It’s hard to say.

  • Annie

    Hi there. I bought a 200 watt flexible solar panel recently as l hire a hi ace hi top from time to time.
    What is the best way to store it at home and use is properly on my road trips, please? Many thanks.