How to mount 100Wp solar panel on Campervan

I am not an electrician and I am doing things more or less intuitive and try a mistake method, so if you find gross mistakes I will be grateful for the warning. Don't stone me now. :-) Yesterday I started to mount a solar panel on the roof of the car. After the Mitsubishi experience, where we almost burned down due to thin cables, I left nothing to chance and used coarse cables that are used to connect solar panels to power plants.

Although they are harder and a little harder to bend, but have a rough insulation which is essential for me, as they will pass through the pillar at the passenger door. The whole electrical assembly in my car consists of the following components:

- 100Wp flexible solar panel
- controller with USB output
- two traction starter batteries
- Cyrix battery switch with permanent connection
- The internal lighting is completely replaced by LED bulbs
- 300w converter to 220V
- Cables, Vago couplings, connectors and fuses

Batteries are traction and both starter. You ask why? Because they proved good for Mitsubishi. The classic battery does not like deep discharging and I fired one like this on Mic after six months of use. Ordinary traction battery can withstand much more, but it does not have enough starting current, so it can only be used to power the car body. Traction and starter can withstand deep discharge and its life is much longer than a conventional flashlight. The first thing I bought was serving for the fifth year and it was getting it until the solar was pretty busy. Everything was connected to her sometimes for three days without moving. Now perhaps she will be a little relieved and the solar will work. At least that is the idea. wink

The batteries are connected to each other by probably the most ingenious thing you can use. If you're thinking about connecting batteries, you can't think of anything better and I know what I'm talking about. I tried permanent connection, battery disconnector and combiner. I'll try to explain how it all works.
If you have permanently connected batteries recommended to be exactly the same in terms of age and wear, which alone is not realistic to achieve, because one will be a moment more load as the other and you have what you did not want. Current will spill between the batteries because they will still want to balance. This alone will bring about their mutual discharges. You don't want this. If they're traction they can bear it anyway. If not, you will fire them as I do. The wise learn on the mistakes of others.
If you put any disconnector there you have to keep it in mind and especially with shorter movements it is annoying. This was enough for me to reject this solution.

If you use a combiner you are well on your way. I had a combiner S2B - 12, which a handy electrician put together so to speak. He took care of the gradual charging first starting then secondary, and also the gradual discharging first secondary and then starting up to the critical threshold needed to start. The batteries were disconnected when not charging. You call yourself great. It wasn't bad, but it had its flies. For the first time, thin cables went into it, so little current flowed into it. Second, I couldn't charge in the opposite direction, and third, I couldn't manually connect the batteries when I needed to. This fought back in Italy where the alternator left and if I could connect them, a second flashlight would take us off the highway cheaper than a tow truck for the 200EURO.

So when he joined Mercedes, he got the word Cyrix and I have nothing to reproach him for. While charging, both batteries gradually charge through thick cables so faster. I can connect the charger to the secondary flashlight, eg in a campsite and charge in reverse order. This will now be improved with permanent reverse solar charging. In case of need I can connect the batteries either to the preset 30s interval or permanently, because after my experience from Italy I put my switch and not the original one. This one can be permanently connected and I do not forget it so shines. It's a useful thing even in the winter, when you move briefly and the starter flashlight comes together. It's easy to use. Does not start? I turn on the button and suddenly I have two batteries instead of one to start and the car starts right away. My Cyrix is ​​located under the passenger seat and the starter cable goes through the middle tunnel between the seats. The knob is on the front passenger seat. It's a pretty tangle of cables. Please don't paint. :-) Just Cyrix forever.

I have the regulator connected between the secondary battery, the solar panel and the body connectors on the roof. My controller also has a USB output that I could forgive myself. In the meantime, I ordered a charger from China that charges 2x2A what it can charge even when navigation and other applications are running. In addition, it alternates between consuming ampere, battery volts, and ambient temperature. What more could you want for 3EUR. The controller has a status indicator of what is happening. Whether the solar is charging, whether there is still power in the battery, disconnects the solar when the battery is charged, disconnects everything if necessary and connects so you don't have to worry about anything. Just consider whether you need a USB output and whether you will use it more than 10A. If not, you can save ten euros for having three of the above mentioned chargers. Of course, the charger will take up space in the car socket so that the USB on the controller can sometimes be justified. The regulator also has a knob with which you can disconnect or connect the entire superstructure. Here it is good that I can access it from the driver's seat.

I have five car sockets in Mercedes. Four are from the factory and one I have finished and is powered by the controller, so it either takes power from the secondary flashlight or from the sun. The driver's front socket only works with the ignition key and, in my case, the charger mentioned above. It gives me an overview of the starting flashlight. In the middle of the car there is one plug on each side, which goes without a key and disconnects the car at low voltage. These guys in Mercedes invented well. The same is the case in the trunk drawer, which I more or less do not use. But there are never enough outlets on the go, especially if you are a technophile like me. One is connected to the 220V converter, two mobile chargers, one claims fridge and the other is a laptop charger and you are without sockets even if you use a power strip. That's why I decided to do the following. The fridge has its own switch and have it permanently in the socket, so it would rather take it via Vago coupling to the output of the controller. Into this Vago clutch came the body socket and cable from the old phone charger, which is winding and at the end I added a connector that uses a laptop charger, cooling fan in the car, mosquito lamp as well as newly implemented fans on the side window. I gave all these appliances the same connector as my laptop charger. Behind the regulator is a cable fuse so I should not burn.

I was already using the solar on MIC, but it was a small 8Wp and was behind the windshield. He could feed a laptop or phone, but not charge it. After using the calculator to calculate the size of the solar panel according to your energy requirements, I came to the 100Wp panel. Of course, the inconspicuousness is alpha - omega for me so it must be thin and flexible so no one can see it on the roof. I got it at a good price, but if you are considering buying be careful about the length of the cable connected. I didn't realize it and it made my life quite difficult. I did not want any couplings in the pillar so I had to place the regulator in the upper part under the seat belt fastener. I didn't want him on the ceiling. In addition, I burned to USB, because it is wider and I could not fit the column in width. He had to go up, which doesn't bother me again, but the original intend to have it down on the post would probably be a better solution. What else, learn my mistake. It also has an advantage. I can also see the driver's position on the charging status. The regulator is under the belt, which can cause the belt to crumple and blast the belt, but it will probably be the last thing I will address then.

There are three ways to fix the panel to the roof:

- screw or rivet. Six holes more than I like ... no.
- permanently glue Sikaflex. A permanent solution due to my eternally dissatisfied nature is not my cup of coffee.
- stick with double-sided tape and tap Duck tap. Who knows me that we have been friends with Duck Tap since he replaced my broken side window on my way to Italy. A clear choice for me.

I had to shorten the panel a little so that it does not exceed the embossment on the roof of the car. Then I would have badly stuck the tape and there would be a place where the wind would lean while driving. I properly degreased the roof and panel and glued with double-sided tape. The tape itself is like hell, and I couldn't move the panel anymore. I taped it for sure along the perimeter still ducktapom. I will test it for a while how it will behave and at worst if it does not hold, I can always put Sikaflex there.
The passage of cables across the roof was the most feared part. I drilled Mitsubishi like Emmental, but I haven't made a hole in Mercedes. So I considered it very much. Adapters, rubber, el. Box, original caravan adapters, cable couplings. It all involved quite large holes for my taste, and it wouldn't look appealing on the roof. In the end, the ideal solution seemed to drill holes in the thickness of the cable into the side of the recess in which the skids are attached. I placed heat shrink tubes on the cables before passing through them to improve the resistance to cutting through the cable in the hole. The cable is, as I mentioned, thick-walled, but certainty is certainty. I drilled the holes above the pillar and pushed more of the bast twine inside. From the inside, there are two holes in the upper part of the post, which attaches the upper part of the post cover. I taped one of the holes and put a vacuum cleaner on the other, pulling the bast twine inside. Inside the hole in the roof and the surrounding area, I sealed the Sikaflex. Better expression on it probably does not exist and one lucky it is from the inside of the roof. While you don't climb it, you won't see it. Side drilling has two other advantages. The cable enters the roof horizontally with the roof, so it is not raised upwards and the holes are about half a centimeter above the roof level so that they are not submerged in the water unless it is really a cloud storm. Of course, water does not stand on the roof while driving. I glued the cables to the panel and roof to Sikaflex -11FC all in one. Here, Ducktape was already pulling the shorter end. This solution is not elegant, but if you do not have more than two meters so it is not visible. I am curious about the first heavy rain and the first highway ride.

So after a month of testing, the tape went down. The first hot days showed that while still holding, but the glue is soft and especially in the bends loose. Under the tape, the air was scooping and began to rise.
So I stripped the tape and removed the remnants without any problems with Toluene. It also degreased the roof and panel so I could apply the above Sikaflex-11FC all in one. Before applying, I covered the panel and roof with painterly paper tape so as not to stain everything. I applied the silicone with a trowel to the silicone and then with my finger soaked in soapy water to prevent the silicone from sticking to my finger. After pulling off the tape, I ran it again with my finger and burdened the panel so that it did not pull away from the roof.

The result looks good and I wonder how it will behave in a month in the sharp Greek sun.





Hotovo :)


I will be glad for any critical comments and any sharing that can help someone. :)






Zdeněk Luk's picture
Zdeněk Luk (unregistered) 12. September 2019 - 23: 21

I went in a similar way, 100W panel on the roof I glued the glue on the windshield. 260V, so that I do not use any inverter.

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