A country like Australia offers a traveler many opportunities to get away from everything and spend some time off-grid and in nature. Of course it is still nice to have a few of the comforts you enjoy in a house. Such as refrigeration, lighting and charging of your electronic devices. Depending on your electrical requirements and the type of camper you have, a solar charging system is the answer.
While I have spent many years working with 12 and 24 Volt solar and battery systems and I like to think I usually know what I am doing, I am by no means an expert. All the same, here is a run down of the system I installed in Elliot, our tiny home on wheels.
The main requirements we had were:
- The ability to stay off-grid for an unspecified amount of time – the longer the better.
- The ability to charge multiple devices at the same time including laptops, phones and cameras.
- Enough lighting both inside and out to work, cook or relax with a book.
- Run a refrigerator/ freezer and occasionally a stick mixer.
The Previous System
In the first camper the solar system was rather simple but functional:
- 2x 120 Watt solar panels, one fixed on the roof and one portable
- 2x 120 AH AGM Batteries
- MPPT Solar Regulator
This solar system I built was successful at first but after about 18 months started to show problems. The main one being the use of low quality Chinese panels. While these were more than capable in the beginning, after 18 months the panels were at half the power and just couldn’t keep up with the requirements.
The company that was selling these in Australia also went out of business about six months after my purchase. The batteries also got damaged when the voltage dropped too low accidentally, as the regulator was not set to the correct minimum voltage. This resulted in the batteries not keeping up anymore with what was required.
The New System
Having learnt from the previous system I included some extras this time. This is a list of all the components:
- 1x 200 Watt solar panel (on roof, permanent)
- 1x 120 Watt solar panel (on roof, removable with stand)
- 2x 135 AH AGM Batteries
- Powertech MPPT Solar Regulator
- DC to DC Charger (to charge batteries from engine while driving)
- Fuse Box (so all fuses are together and easier to identify)
- Multiple USB and 12 Volt Outlets
We decided to get German made solar panels this time, hoping for better quality and longer lifespan.
We have two solar panels on our roof. The first panel is 200 Watts. We screw mounted it to aluminium rails that we previously welded to the roof structure. The second panel is 120 Watts and locked to the roof rails at the back of the camper with clips. This allows us to easily remove the panel. It has a custom built-in stand so we can set it up in the best location when required. (So far we have only needed to do this once.)
I have found previously that the solar connectors did not last very long in saltier environments with corrosion and dirt/ dust ingress. So I replaced them for both solar panels with Anderson plug connectors.
Below are the Anderson type plugs we used and found to be reliable. They are considerably cheaper buying them online as opposed to a store.
The solar cabling is a Heavy Duty 2 core low voltage cable. We ran these cables through a waterproof gland into the inside of the roof and inside a 25×25 SHS, which is a part of the roof structure. They come out at the hinge side of the roof and continue into a 20mm corrugated conduit all the way to the electrical main board. Here both cables are connected with another Anderson plug (allowing a quick disconnect if required) to the MPPT Solar Regulator.
Behind the Main electrical board sit two 135 AH AGM batteries. These are connected directly through an Anderson plug (again allowing quick disconnect if required) to both the MPPT solar regulator and the DCDC battery charger. Unfortunately these batteries are rather heavy at 32 kg each.
We would have preferred to use the much lighter and better Lithium batteries but the best price we could find at the time was about four times more expensive than the AGM batteries. Maybe this can be a future upgrade. The two batteries are mounted together and held in position in a wooded box lined with rubber. These batteries are sealed and maintenance free and so don’t require a top up or ventilation.
Main Electrical Board
The main electrical board is made up of three components. The MPPT solar charge controller, the DCDC charger and the Fuse box.
The MPPT solar charge controller
MPPT stands for Maximum Power Point Tracking. The difference from a standard charge controller or regulator is in very basic terms that the MPPT controller reads the voltage of the battery and then changes the voltage from the solar panels to maximise the charging. This is even more important on cloudy or hazy days as the MPPT charger will extract maximum power from the panels.
This is the MPPT Solar Charge Controller we are using:
The DCDC charger
The DC to DC charger is a new addition which we didn’t have in the previous vehicle. It gives additional charge while driving which is a bonus as the solar panels are not always optimally aligned with the sun while driving. With this system we arrive at camp with a full battery.
Also, if we happen to be camping in a very shady location or have a week of very dark cloudy weather we can run the engine for a while and top up the batteries. We have not needed to do this yet but it would have come in very handy with the previous setup we had.
See below the Redarc BCDC1220 we are using:
The Fuse box
This was a last minute purchase when we realised just how many fuses we needed to install. Having a large number of inline fuses can be annoying when you have to identify each wire to find a problem. The fuse box is a cheap one available on Ebay (see below) but has proven to be reliable and very convenient. When a fuse has blown a small LED is lit to make it easy to identify which fuse to replace.
This is the fuse box we are using:
We used LED light strips throughout the camper, warm white for the living space and cold white for the tool storage.
For additional lighting next to the bed we installed two flexible gooseneck reading lights.
In the kitchen door we also have two LED down lights to be able to vary the lighting.
Switches and sockets
All lights, the water pump and the extraction fan have separate switches.
In the interior we installed several USB and 12 Volt sockets as well as a 12 Volt socket for the fridge in the kitchen.
We hid all cables either inside the aluminium tubular frame of the camper or behind the wooden paneling with the insulation. We often utilised a vacuum cleaner to suck a string through the tube and then tied the cable to the end to pull it trough.
Before starting starting to wire up any camper, make a detailed list and plan of where you want to have lights and sockets and run the cables before insulating and cladding. If you have any questions, feel free to contact us. We are happy to help!