Igor….throw the switch….It is Alive!!
I’ve never been camping where power wasn’t a requirement. While some might like the unplugged serenity, I prefer to have a charged phone on hand to post Instagram-worthy pictures of my friend asleep in a camp chair with a beer can on his head. In the case of the van, the power requirements are increased due to the fridge, lights, water pump, extras, and of course the aforementioned phone charger.
In General, there are 3 power options available
- Generator – either gas powered unit or a battery pack
- Shore Power – you plug into an outlet at the campsite
- Solar – you generate your power from the sun
I have a Predator 3500 generator, but it’s noisy, it’s bulky to carry around and requires gas which also requires carrying around. I briefly considered a power bank but the price point isn’t within acceptable limits right now. So, Solar it was (I’ll get to shore power later). I’m not unfamiliar with solar power having been involved in electronics for the first few years of my career and having built a portable solar unit for Burningman one year. For the van though, I was going to need something a bit more substantial.
Pre-ramble – Important stuff
Before we get into the details of what I put together, I want to bore you all and talk a little bit about power. Your phone uses power, your fridge uses power, your lights use power. Differing amounts of course, but they all use it. Power is generally measured in Watts (mega-watts for your house and jiga-watts for your average time traveller), and there is a simple relationship between Volts, Amps and Power.
Power = Volts x Amps
And, if you know your math transformations, you’ll therefore know that
Volts = Power/Amps
Amps = Power/Volts
It’s important to understand this because you’ll want to make sure you have a system that can deliver the power, and components that can handle the power.
Consider a 12v20w rated light bulb. What kind of current will it draw? Since we know that Amps = Power/Volts we can calculate that 20 Watts divided by 12 Volts = 1.6 Amps. Start-up amps for most devices are often a little higher (there’s always a short ‘spike’) so let’s say that you would need a cable that can handle a current of 2 Amps. Now consider all the devices that you have and when you sum up, you’ll have an idea of the amount of power you’ll need your system to deliver. This will all make sense when I walk through the system I have. There is an additional complication of cable length, but in most cases I have short runs.
Because Solar relies on the sun, which can come and go throughout the day due to cloud cover, shifting angles of the sun on the panels and simply daytime vs night time, the solar panels themselves cannot be relied upon to deliver consistent power. Therefore the power is supplied from a battery, and the solar panels charge the battery through a controller that ‘smooths out’ the panel output to something that the battery can accept. That gives us the 3 main components of a solar power system. The Panels to convert the sun’s rays to electricity, a controller to regulate the electricity received from the panels and a battery to store the generated electricity and meet the power requirements of the attached devices.
My Solar Solution
Phew…ok…now that’s all out of the way, let me explain what I have, how I assembled it, and where it’s placed (I know you were on bated breath since I mentioned it in the previous post regarding the bed frame). For a full list of everything I used see the end of this post.
My power requirements are pretty low at ~100 Watts. This covers the fridge, lights, and phone charger, but excludes anything I might want to plug into the 110v socket. It’s always best to have more power than you need. Searching led me to a 200 Watt solar package complete with a 40 Amp MPPT controller (an MPPT Controller is much more efficient than a PWM Controller so get the former if you can).
As mentioned, a battery is required because of the varying output from the solar panels, and the need for something that can provide continuous power when the panels are not generating energy, eg at night. In my case, I went with a single 200Ah LiFEPO unit.
Of course, you also need cables, switches, fuses, connectors…but we’re about to dive into that…
Connecting it all Together.
I recommend you lay everything out beforehand so you can map out cable runs, component positions etc.
My solar package consists of two panels which I mounted on either side of the roof using the supplied brackets. I considered just using 3M VHB tape but for safety’s sake, I drilled through the fiberglass roof and secured the brackets with bolts and nylock nuts. The cables were passed through a cable entry gland and a hole drilled into the roof, fed down the inside, and secured by cable ties. When assembling the system, the solar panels are the last thing to be connected. This is important.
I located the battery under the bed frame and the first thing I connected was the shunt. A shunt is a device that measures the amount of current going to or from the battery. It will tell you if your battery is being charged (by the solar) or discharged (by the devices connected to it). Using this you can get an understanding of the rate of discharge and how long your battery will last before it’s depleted for example.
The shunt sits between the negative terminal of the battery and the negative busbar. Nothing else should be connected directly to the negative battery terminal or your shunt will incorrectly report energy usage. This is where the above calculations start to come into effect. I have a couple of appliances that draw a total of 100 Watts but I also have a 2000 Watt inverter to provide 110v ac. Since the amount of current this would draw can be calculated by 2000 Watts divided by 12 Volts, I need the main cables from the battery to the busbars to be able to handle at least 166 Amps. Here is a link to a popular cable sizing chart.
As before, we want to account for the overage and start-up current so I went with a 2/0 AWG cable (70mm2) rated at 200 amps between the shunt and negative busbar and the same for the positive busbar via a 200amp fuse and master switch. Fuses should always be placed as close to the power source as possible to protect the cable.
From the negative busbar to the inverter is another 2/0 AWG cable, and from the positive busbar a 200amp fuse and 2/0 AWG cable.
My solar kit includes the cables and MC4 connectors and the solar panels connect to the MPPT controller input via a double pole switch. Keep this switch off until everything is connected. The MPPT output is connected to the positive and negative busbars via 40Amp Circuit breaker. Again you can calculate cable size needs using the same formula but the MPPT is rated at 40 amp so I went with 4 AWG cables.
Connections are made via crimped terminals and heat shrink tubing. This method is far superior to soldering since soldered connections don’t stand up well to the vibration that occurs in a van on the road. Again, links to everything I used can be found at the bottom of this post, including the crimping tool I chose.
All of these items were mounted to a 48” x 16” board which forms part of the bed frame and is attached by hinges.
So in the ‘down’ position the mattress lays flat and to gain access to the electrics, I simply lift the mattress and then lift the board. Now you understand my bed frame decision…was it worth the wait??
I have the rest of my 12v feeds off of the busbars. I have a 5-gang rocker switch panel with both USB and 12v cigarette socket outputs. Through these switches, I’ve wired my fridge, ceiling lights, sink water pump, and an auxiliary fuse box for expansion capabilities. The same process again for calculating cable size and fuse needs (each circuit has its own fuse). This panel is mounted to the bed frame facing the inside of the van. Next to this is a recessed 110v power strip connected to the 110v output from my inverter.
Finally, when everything is wired up, turn on the master switch to connect the battery and then flip the isolator to connect the panels. If everything is working as it should the MPPT controller will show the state of charge (in my case it was the middle of the day and so the display indicated that the battery was being charged by the solar panels) and the shunt app indicated a negative battery current (current going in instead of coming out). And that’s our power needs sorted. Comments and questions are welcomed.
For a video walk-through, see here – https://www.youtube.com/watch?v=V03XkwdFUEA
Components
Solar Kit (Panels and Controller)
Battery
Shunt
200a Fuse
Fuse Holder
Switch Panel
Inverter
Double Pole Switch
Master Switch
Busbars 1
Busbars 2
Cable Gland Entry
Bluetooth Module (optional)
Tools, Wires and Connectors
2/0 AWG cable
2/0 Terminal connectors with heat-shrink tubing
14 AWG cable
Assorted Terminal kit with heat-shrink tubing
Crimping tool
Zip Ties and mounts