Saturday, April 13 2024

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.


My custom built overhead storage unit


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About Author

The Moonraker

A complete self-confessed VW nutjob. My VW T4 is actually my first and only VW I have ever owned but I love it. Having bought my van as a straight forward panel van, I enjoyed the process of converting it how I wanted. Now the van is all done, it's getting out and exploring I love to do.


  1. UPDATE: Unfor­tu­nate­ly Lensun have decid­ed to dis­con­tin­ue this par­tic­u­lar pan­el, how­ev­er, they do still sell a slight­ly larg­er (should still fit) 55w version.

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