The overriding and deciding factor will be how much space you have on your roof. This will determine your solar array. The next consideration is what you are wanting to power, eg; lights, fridges, TVs, laptops and mobile phone chargers are all needed and some devices use more power than others. Your system will need to be configured in relation to how you camp or boondock. A good starting point is to have 100w of solar panels for every 90w of power usage, with the ability to put back the power used every day.
Do You Camp Or Boondock?
Some people only require power while traveling from campsite to campsite, with a campervan being the only form of transport you have while away on holiday, you are unlikely to be stationary on a pitch for long periods. Your campervan will be started and moved every day or two which during this time your leisure battery will be charging by the alternator via a split charge relay system or use a DC-To-DC Charge Controler. One or both of these systems provide to re-charge capacity to your leisure battery which in most cases is enough to maintain power for short holiday periods. Equally, there are full-time nomad travelers who require much more power due to boondocking and wild-camping instead of moving between campsites. This off-grid lifestyle requires much more consideration and planning of your solar 12v power solution.
Types Of Solar Panel
Rigid frame soar panels are more popular with motorhomes, caravans, and campervans as they return the best investment in relation to charging power. With the development of flexible-solar panels becoming more durable and efficient, they are becoming more of an option due to their ability to be placed on curved surfaces. If you are not keen on drilling mounting holes in your motorhome or campervan, then a folding or briefcase solar panel solution could be the best option for you. Whilst they allow you to position the panels in continuous direct sunlight, easy to set up, and allows you to keep your vehicle parked in the shade, the compromise is that you need to have a place to store the folding solar panel when moving. Also bear in mind the possibility of theft as the panel is more accessible on the ground and not on the roof.
Designing your system
It all comes down to you matching your power-generating ability to your lifestyle power requirements. Please see my article on ‘Best Motorhome Leisure Battery 2021’. for your battery storage requirements and INSERT SOLAR AND DC-TO-DC CHARGE LINK HERE for your battery charging options. You may also want to look at my 12volt appliance recommendations for a list of appliances you will need to run in your motorhome or campervan. Here are some examples of the appliances and accessories you may use: Inverters, Compressor fridges, 12v Vent Fans, Water Pumps, LED Lighting, Heating, and Cooking. If you have a laptop that requires charging, then you need to consider running your inverter.
When designing your 12v solar system, you must consider the continuous and instant charge in Amp-hours fed to your battery system, since the appliances may want to run in all weather conditions including cloudy and rainy days. Make sure you can store enough Leisure Battery power to last, even throughout the night allowing you to charge later by Solar, DC-to-DC or Shore Power.
First, you must consider all your power requirements, then assess how much power you can generate, (Get help and advice from a professional if needed). Your traveling, camping, and boondocking behavior will dictate how you set up your system. One consideration most people overlook is the space they have internally and externally for Solar MPPT Charge Controllers, DC-to-DC Chargers, Shore Power Chargers, Fuse Boxes, Plugs, and sockets, not to mention outside considerations including space for solar panels.