Fitting solar panels
I decided on using two 100W slimline solar panels. These are 12V and Monocrystalline which means they are supposed to be more efficient than the poly version and they last longer with a 25 year guarantee on them. This is good because they are going to be exposed to the wind a lot more when driving along and of course the hot sun of foreign countries when travelling around. They also give better results in the winter months as they still get energy from the solar rays even when cloudy.
I had to make sure that the grooves in the roof of the van fitted nicely over the plastic chocks that i had made so that when i pressed the solar panel onto the van roof it fitted nicely in between the grooves so that when it was screwed together tightly it did not crumple the roof but held the solar panel strongly on. I also put silicone sealant around the edges so that any water is prevented from going inside.
This brings me onto the next topic of storing that energy. To store the energy you first need a solar charge controller. Whilst this is not totally essential you would have to maintain the batteries yourself if you didn't have one of these. This ensures that the voltage going into your battery is at an acceptable level. Solar panels even when rated at 12v will give off anywhere from 1v to 20v i have found. A smart controller will know the voltage of your battery and know when it is full or half empty and will charge it with the correct amount of volts and amps to ensure it is charged carefully and efficiently. This increases the battery large hugely. This also helps to keep the battery fully topped up at all times. I chose a company called Victron who make world class battery/solar/inverter energy systems. The controller I have constantly monitors the voltage and current output of my solar panels. It uses MPPT technology to ensure that every drop of available power is rinsed out of the panels, and harvested for storage. The advantage of this is most noticeable when the sky is partially clouded, and light intensity is constantly changing. Read about it here.
I fitted the solar charge controller under the sofa area near the main electrics. I also added a double pole cut off switch to kill the solar panel connection to the charge controller. The solar controller feeds the battery direct usually but in this case my feed to the battery goes through the smart meter which i will explain more about in another section. This essentially provides my campervan display with the current output of the solar so i can see how much power is being put into the battery at all times.