I wanted to be able to use the van without a need for electric hook ups and staying on camp sites. I purchased two of these 100w flexible solar panels (ebay link) from ebay on a 3mm plastic backing. They may suffer from more degradation in hot conditions than aluminium backed panels would so bear that in mind if ordering. The advantage of these however is that you can stick them straight to the roof and they don’t add much to your van height or have much effect on wind resistance.
UPDATE: After 18 months on the roof both of the flexi solar panels failed. I have since read countless reviews from others with a similar experience and I have yet to hear of anyone with flexi panels that have lasted more than 2 years. I’d strongly recommend going for a rigid panel. I now have a 300w rigid panel fitted and it’s working great. It also has a 30 year warranty for the output and 12 years against faults.
I started by painting the fibreglass roof. This wasn’t necessary but as fibreglass is degraded by sunlight I thought it would be worth doing. I used Dulux weathershield outdoor gloss paint with one primer layer and one top coat.
Before fitting the panels I tested them by connecting them up to my charge controller and batteries with them laid out on the lawn. They worked great so the next step was fitting.
I stuck the panels to the roof with SikaFlex EBT+ it seems to be the most recommended sealant for campervan conversions as it stays flexible even when set. They do sell a caravan version at 3 times the price but I am assured it’s no different to the EBT+. Once the sealant had set I went round the edge with silicone sealant for added protection
The cables enter the van through this entry gland (ebay link).It’s stuck to the roof with EBT+. As I was using a PWM solar charge controller I needed to wire up my solar panels in parallel (doubles the amps). With a MPPT charge controller you can wire in series (doubles the volts) these controllers are more expensive but gain more power from the sun especially on cloudy days. I have now moved to a MPPT charge controller which you can read about in this post.
You can see my PWM solar controller mounted to the wall in one of the photos below. You can press the buttons to go through readings such as panel volts, panel amps, battery voltage, load amps and it shows what charging mode the controller is in such as bulk, absorption & float. There are a couple of USB ports on the charger that let you charge up your devices and that comes in handy.
The solar charge controller is wired up to the batteries (these live in the sofa box) and it’s also wired to the load (the electricals that you use, lights, etc)