From the initial stage, I was keen to get a solar panel on my van. I could charge a leisure battery directly from an engine if I was travelling constantly but I was probably going to be stationary most of the time. And I wanted to learn how to set a solar system up so that I can do it in the future when I eventually build my own house. There are plenty of websites and videos out there that explains the next process in more detail so I’ll keep it quite basic.
The initial task was to figure out all the electric equipment that I wanted to bring with me or to install in the van and to list out their power usage. My laptop, phone, speakers, headphone, battery pack, camera, extractor fan, the number and types of lights to install etc. And jot down exactly how long and how much I used each item. This allowed me to calculate the exact amount of power I needed per day which came to about 33 amp hours.
I then had to decide how long I wanted the battery to last if there was no power coming in from the solar panel during long periods of bad weather, which is a fairly common thing in the UK. I decided that if it lasts for 3 days without power input, it will suffice. This came to about 100 amp hours for 3 days. Now, because lead acid batteries should not be depleted to less than 50% of its capacity, I doubled the size of the battery to over 200 amp hours. This means that even after 3 days of no sun, it will still stay above 50% capacity.
This calculation of how much power I use and the battery size required then allowed me to calculate the size of the solar panel needed to power it, which was 150 watts. I opted for a flexible solar panel as they are only a few millimetres thick and can be flexed to fit the curvature of the roof, keeping the aerodynamics of the van low and save fuel in the long run but also keeps the van highly stealthy. A really good thing to aim for as camper vans tend to get targeted for theft.
Planning and ordering
Most solar panels produce electricity in 12v DC but our household items are usually in 240v AC. I won’t get into the technicalities of the differences, but in order to run your normal household items, you’d need what’s called an inverter. There are multiple types of inverters and can differ in efficiency but you always lose some energy in conversion. I do have a 400W inverter which powers my smoothie maker and some power tools but I only switch it on when I need it. Everything else was designed to run directly from 12v DC.
There are a growing number of electronics that run off 12v DC including a mini fridge which I was highly tempted to buy. And with a few purchases like a cigarette lighter laptop charger and plenty of USB outlets, I could maintain a fairly high level of efficiency. One thing to note though, DC is not very good at transporting energy over long distances and requires a thick (=expensive) cable in order not to loose power.
This was not a problem in wiring such a small space as my van but I did draw out a plan with power flow and fuse placement, calculating the cable diameter needed for each section depending on how much power was to flow through it. For example, a relay charging system with max 42 amps flowing from the car engine would require a 6mm diameter cable, whereas one that powers a 6 amp fan would only need to be 1mm and so on. I luckily had a friend who was an electrician so had my plan checked and got a thumbs up.
I ordered the battery (about £180) solar panel (about £140), charge controller, cables, connectors, switches, cable stripper, LED lights and a fan on ebay. All in all roughly £400. This may seem like a lot, but if you use them well, the battery will last well over 5 years, and solar for over 20 years. And I get mobile off grid power supply directly from the sun.
I stuck the solar panel using industrial velcro and sealed all the edges using high strength sealant specifically designed for camper vans. After a year, however, one of the attachment to the panel broke, probably due to driving under a tree and a branch bashing the connection. When I stripped the sealant off to replace the panel, there was a puddle of rain water that had seeped in from somewhere and light speckles of rust was starting to form. They have somehow found its way in but could not evaporate due to lack of drainage and ventilation. I was actually pretty glad that the solar panel had broken sooner rather than later so that I could fix the issue before it became a massive problem. With the lesson learnt, I attached the new panel with gaps big enough to drain water and aerate.
Due to the panels coming with only a few meters of cable, I had to place the charge controller right next to the driver seat, behind a board that separates my kitchen and the cab. I regret this decision quite a bit since not being able to monitor the battery levels have lead me to discharge the battery completely once. (I have since worked out that the charge controller has a discharge limiter that can be set to whatever figure you want.) I would recommend anyone building a solar system to purchase extra cable and place it in a good visible location so that it’s easier to monitor your usage.
I also made the mistake of placing the fuse box under the hob where I have to first move my mattress, floor boards and stuff underneath it in order to access it. If I was to do this again, I would make the whole system accessible within one step.
I calculated the volume of air within the van and bought a 12v fan on ebay that could sufficiently extract cooking fumes etc. It was placed above the cooker and it sucks the air well enough plus it’s relatively quiet. It came in really handy when I was stealth camping in Edinburgh for an extended period of time, as it was discreet and can be operated in places where opening windows and doors might not be a good idea. I’ve also used it to vent hot air out during summer and it does work to some extent. I’m glad I had installed it but now that I’m in the countryside, I just open the window and doors which works far better.
I bought an excessive amount of lights for such a small van. 6 spot lights, 6 down lights and fairly lights that are wired around the circumference, all of them LED for efficiency. However, I highly recommend diversifying the lights as it’s easier to not switch on the light, then to having to redo the cabling and install new ones. I’ve also found out that it allows many different lighting configurations which changes the scenery and gives an illusion of depth. When I’m working at night writing this blog for example, I may have all the lights on, whereas before going to bed, I might just have the fairy lights or the desk lights. A more diffused but brighter light when cooking and overall spot light where I enter and exit and so on. They’ve come a long way in achieving a much warmer colour than they were even just a few years ago.