Fitting Lensun semi-flexible solar panels
Ever since fitting out the van I’ve always wanted to use solar panels to keep the charge up on the battery so that I have no problems using the fridge while away, which is usually somewhere without electric hook-up. Problem is, most of my trips away mean the roof is covered by my 9′6″ longboard or the roof box so until now I have been using an 80W portable briefcase type which is fine, but not practical if parked anywhere other than a campsite. However, recently I figured that there is plenty of time that the surfboard is not on the roof (like when I’m in the water), this would give the battery a chance to charge.
Due to the roof rails and bars, a rigid solar panel would be difficult, and there is no room at the front of the roof due to having a sunroof. This is the reason I chose to go for flexible panels, but they would need to fit between the raised areas of the roof. On doing some research, the best panels I found were by Lensun Solar Energy, which do not use PET like some other cheaper panels, these are also available in black so less visible on my black roof.
I decided on two panels in parallel, it’s the amps I need, not the voltage and this way I was more likely to get power, even when partially covered.
Using 2 x 50w panels wired in parallel is plenty enough power to keep my 130AH leisure battery topped up and to use my fridge constantly as well as keeping any electrical devices like laptops or phones in good order.
The first step was planning (of course), so having considered how to run the cables to the inside, I thought the best way would be to drill a hole next to each panel feed the cables through entry glands, one for each panel. This meant cutting off the MC4 plugs at the end of the cables (no doubt voiding the warranty). Although not strictly necessary, I chose to reconnect MC4 connectors on the inside of the van in order to also fit t‑pieces before connecting to the Solar Panel Voltage Regulator. The Regulator has been fitted to the van for a while now as the previous external solar panel connected to it.
After removing the panels so that I could make room to feed the cables through, I got to work on the roof. To ensure the panels are really secure I opted to bolt through the roof. I know a lot of people don’t like putting holes through the roof but I would need to for the cables and bonding with Sikaflex would cause just as many problems with regard to damage if removing, plus, if ever I need to replace a panel it should be much easier. The first thing was to position everything within the panel and mark up where the holes and cable entry gland would be, I wanted to keep this fairly stealthy so minimum cables showing on the roof.
Once marked up, I started on the holes. The cables feed through a 57mm hole beneath the entry gland, this was cut with a 57mm hole saw. Others have drilled just holes for the cable, but if ever the panel needed replacing, I couldn;t see how you could feed new cables through without also removing the cable entry gland.
The holes for the bolts were drilled using a 10mm HSS drill bit, I am using M10 20mm counter sunk bolts to secure the panels. After the holes were drilled, I touched up the bare edges with a bit of Hammerite black paint, it didn’t matter how this looked as it would be covered, but hopefully will reduce any chance of rust from moisture getting in from beneath.
The cable entry glands were then placed over the holes and secured using Sikaflex 221, this will give them a good bond and keep any water running from the roof.
I also used a little bit of Sikaflex 221 around the bolt holes to stop any water seeping through and to add a little extra strength.
The panels were then put in place and the bolts secured using a washer and nut beneath. This was a little tricky doing on my own when trying to tighten both the allan key bolt and nut at the same time, but managed OK in the end.
With the cables fed through the holes, I could then begin the wiring to the battery. What you do not see on the picture below is a piece of foam I also added to the holes to ensure the cables do not rub against the edge of the holes.
The cables were then fed down the side of the panel as per the wiring diagram and the beginning of this post. I realised access to the 30 amp fuse would not be easy once the panel is back on, but not expecting this to blow any time soon. The regulator just attaches to the wheel arch via velcro, next to all my other electrics. The battery is very close to this and I already had a fused cable in place to the battery from when I used my portable panel so that part was already done but is fairly simple. The RC4 plugs and sockets are very easy to put together when using the RC4 clamp which can be purchased fairly cheaply online.
Finally, with the panels in place on the roof I added a bead of Evostick black roof sealant around the edges. I figured this would be easier to work with than the Sikaflex, should I need to remove at any time. I have to say, my applying sealant skills are rubbish and it wasn’t long before I was making a right mess so was glad I never used the Sikaflex, the extra sealant came off fairly easily with white spirit and soapy water so was much easier to tidy up, I still probably need to tidy a bit more but as soon as I was finished the heavens opened and it rained for two days, fortunately a good way to see if anything leaked, fortunately nothing did.
Looks like I’ll never have to constantly worry about the leisure battery running down, even when cloudy there were a couple of amps getting through and my volt reader for the battery is now much higher than before. Happy days! Will wait and see how it performs when I have my surf board on the roof.
I hope this helps anybody thinking of doing similar, leave a comment if you would like more info on any part of this post.
DISCLAIMER: I am not a professional solar panel fitter, this post simply explains what I have done after researching online, however, I hope it may help others in a similar situation.