When we were new to the world of campervan electrical systems and solar power, we found the whole idea of it to be bloody overwhelming! There’s plenty of information online, so much so that it left us with more questions than answers most of the time. We binged Youtube videos, write ups and Instagram posts trying to absorb as much knowledge as possible. The time came to do our first electrical system in our school bus, and still very unconfident, we dove in and gave it a crack. That was when we realised it was completely doable!

This article is an attempt to make things simple and straight forward for those of you looking to install your own off grid electrical setup. We want to share what we have learned over the past 3 camper conversions and show you how and why our new solar setup is the way it is!

DISCLAIMER: This post details what we have done for our own build based on the research and experience we have gathered. WE ARE NOT ELECTRICIANS. Working with any electrical system can be dangerous if not handled correctly. Always follow the manufactures specifications and consult a licensed electrician before performing any electrical work. 

Everything We Used in Our Electrical Setup

Let’s get the juicy part out of the way first and show you everything we used to power our van completely off grid. There are many ways and heaps products to achieve the same results, hopefully this list helps narrow the search fields for you. We’ve used this setup for 5 months now and can honestly say it works a treat! 👌👌

The Main Components

Other Necessities

Tools Required

• 18V Cordless Drill

• Wire Stripper/Crimp Tool

• Assorted Screw Drivers

• Adhesive/Sealant

• Assorted Drill Bits

• Soldering Iron

• Insulation Tape

• Caulking Gun

What is this stuff and why do you need it?

There’s a fair few things on that list, some of which you may be familiar with, others you might know existed until now. Don’t worry! We’ll break down each component and let you know what they’re for. 

The Sun:

Free and available for everyone to use! Make the most of this giant ball of energy in the sky by harnessing it’s power to run your lives. We don’t know how all the sciency stuff works, but thankfully we don’t need to!

Solar Panels:

These absorb the power from the sun and turn it into sweet electricity! They then send the power out and off to the charger. 

Battery Charger:

As we mentioned there are a lot off different methods and products to achieve the same results. You need to charge the battery somehow, and this can be done through the solar, the vehicles alternator, or even both! We chose a simple all-in-one unit that took care of all our battery charging needs. 

Batteries:

These store the power generated by the solar or alternator, and are then used to power up all the electrical components in the van.

Inverter:

This is used to convert the 12v power of the batteries into 240v (like the wall sockets in your home). This is needed to run more complicated electronics like laptops, battery chargers and even blenders. 

Fuses and switches:

These are essential for every installation and are used to protect us in the event of a failure with the system wiring or its components. Every component will tell you what fuse you need where, so check the manuals for the info!

That’s the bare basics of every campervan electrical set up. There’s a setup for every budget so if you need help figuring out what’s right for you, head over here and send us a message. 

Choosing the right components for your needs and budget

Now you know what goes into an off grid electrical system, you’re probably going to start looking online and piecing your own setup together. This can seriously take up days of your time trying to find what’s right. Here’s some helpful tips to help you narrow the search and find what you need:

Solar Panels:

There are two different technologies in the solar cells that determine how efficient a panel will be - Polycrystalline and Monocrystalline. The ‘mono’ panels are always more efficient due to their build, but are a little more pricey because of it. ‘Poly’ panels are much cheaper and do generate power from the sun, but need to be much larger to produce the same as a ‘mono’ panel. 

There are also different physical variations for solar panels. Depending on the surface you have to mount on, you may choose a thin, flexible glue-down panel. Have some roof racks? Put up a permanent fixed or rigid panel to get power 24/7. Just wanting a small weekend setup? There’s all in one portable solar panels that you can pull out and power up with wherever you’re parked up. The choice is yours!

Battery Chargers:

Let’s break down the 2 main ways of charging your second battery, and what components are best for each method. 

Charging from the alternator while your vehicle is running: This is a great way to get some extra juice into your second battery while you’re cruising along, and can also help top your battery up quickly if it gets too low. The basic method is to use a Battery Isolator or VSR (voltage sensitive relay). This simply connects to both your main/driving and secondary batteries, and when your main battery reaches a high enough charge, it flicks over and starts to charge your second battery as well. There are also units called DC-DC Chargers that do the same thing, but are more efficient/reliable (I believe), and also usually have inputs to charge the batteries from solar as well. Super easy and all in one!

Charging from Solar: This is the other common method of charging a campervans second battery, and can easily be paired with the above options to really get some power into the battery. You can’t just plug up your solar wires straight to the terminals though! There needs to be a component in between that monitors and regulates the solar power to prevent over charging and a whole lot of problems. This is where solar charge controllers come in.

There are a couple of types of solar controllers to be aware of. The PWM type are cheap, basic and do an okay job of charging your batteries. The ideal type and one we've always used is the MPPT type charge controller. These use the solar power much more efficiently and often have a lot more programing options to get the most life out of those expensive batteries! 

To get the best charge for your batteries, we highly recommend charging from both the solar AND vehicle alternator. The cheapest (but not necessarily the easiest) way would be to buy a basic VSR, a PWM Solar Controller and a budget Solar Panel, and then use these to power your setup. The most recommended way is to use a DC-DC Charger with built in MPPT Solar Controller and a good quality fixed solar panel. This is the simplest to install and will be a good reliable setup for years to come. Do it once, do it right hey!

Batteries:

It's important to know what battery best suits your needs to avoid issues out on the road. Standard flooded lead acid batteries like the one that powers the vehicle can be used, but they're not made to be deeply discharged and charged repeatedly. They also give off toxic fumes when charging so cannot be put inside the vehicle. The next option and the most commonly used for the past few years are AGM Deep Cycle batteries. These are a major upgrade from the old technology. They're designed be drained and charged repeatedly (although shouldn't be drained lower than 50% capacity to prolong life) and are completely sealed, meaning they can be stored at any angle and are safe to have charging inside the cabin!

If you've got the cash, we highly suggest looking into Lithium or LiFePo4 batteries. These are fully sealed like the AGM ones, but can be completely discharged so you basically get twice the capacity for half the space and weight!

1x 100ah AGM battery = 50ah usable power

1x 100ah Lithium battery = 100ah usable power. 

Inverters:

Again 2 different technologies that give different results - Modified Sine Wave and Pure Sine Wave. Modified is the cheaper of the two and will work fine in some instances. With laptops and other appliances being so advanced these days, they need a 'cleaner' sine wave to operate properly. Pure sine wave inverters are the go to, and come in a range of sizes (measured in watts) to suit your power needs!

Need help choosing the right sized components for your needs? Give us a message and see how we can help! Alternatively, there heaps of online calculators to help you figure things out. Check out https://www.redarcelectronics.co.nz/calculator/solar as a start.

Time to begin the install!

With everything needed to take our vans electrical system to the next level, let's start installing!

Step 1: Installing the Battery.

Figuring out where you want to house your auxiliary battery and other electrical goodies is the first step. If your charging from your alternator, try put your second battery as close as possible to your main/driving battery. This will minimise voltage drop due to long wires and also saves you some coin. Wires are expensive! This area needs to be big enough for each component to have some 'breathing space' around it, as well as a bit of ventilation to expel heat. We already had a second battery area under the seat right behind our main battery, so it was the perfect spot to install all our components. We chose to use the Camec 120AH AGM Deep Cycle Battery.

With the spot chosen, you now need to mount/secure the battery. This thing can turn into a 40kg missile in a crash if it’s left loose! We screwed some timber to the floor with a heavy duty strap sandwiched underneath. This buckles over the top of the battery to hold it in place. We then connected a thick gauge wire from the negative terminal of the battery to a solid metal surface on the van to earth the battery.

Step 2: Installing the Solar Panels.

Time to head up onto the roof and look at installing the solar panels. We chose 2x Redarc 150w Monocrystalline solar panels which pull in plenty of power for our needs. We went with fixed rigid panels for efficiency but they have added a bit of weight to our pop top roof, so in hindsight the thin flexible panels would have been a better fit. Anywhoo, here's how we put them up securely!

We started by giving the roof a good clean and then wiping down the areas where our Panel Mounts would be with Mineral Turpentine. This give a good surface for the adhesive to stick to and prevents lifting/leaks in the future. We used some extremely strong Sikaflex 552 AT adhesive/sealant that works really well. While people do secure panels with just the adhesive, we wanted to be 100% sure they weren't going to fly off, so we used Stainless Steel screws for some extra hold. 

Sitting the panels in the bottom half of the mounts and positioning it where we wanted on the roof, we marked out where the mounts sit and removed the panel. We then drilled pilot holes for the screws and wiped away all the debris. Time to glue and screw these puppies down! We go by the motto of 'more is more’ with adhesive, so don't be afraid to put a decent amount on. After applying the adhesive around the boarder of the mount base, we lined it up with our pilot holes and began to screw the mount down. Make sure to tighten the screws down evenly to get good uniform contact with the roof. Repeat these steps for the remaining corner mounts. With the mount bases in place we can now sit the panels back in and secure them. Screw on the top half of the mounts and tighten the locking screws to hold the panels in place.

WARNING: The solar panels are live and producing power whenever they are in the sun. Blank off exposed wire ends with electrical tape to avoid touching them to each other or anything else!

Now we have the solar panels mounted we can look into the wiring for them. Every panel will only have 2 wires - a red/positive wire & black/negative wire. Each cable has a MC4 Waterproof Connector on the end (male on the positive, female on the negative). These give a good waterproof connection for the external joining of wires and make it nice and easy to plug in a Solar Extension Lead to make the cables long enough to reach inside the camper. Now, here’s were things get a little tricky - if we were installing one panel, we’d plug in the extension cables and be done with it. Having 2 or more panels makes things a little trickier and requires some info and thought. We’ll try keep it simple!

There are 2 ways of connecting an electrical circuit - series or parallel. In a series circuit, the components are linked end on end (positive to negative to positive etc). In solar panel applications, this will mean that the total voltage will be ADDED across the components, and the total amps remains the same. EG. 2x solar panels with a voltage of 12v and an output of 5 amps wired in SERIES will generate 5 amps of power at 24v. Series wiring for solar panels has its uses, but having the panels connected one after the other means that if one panel fails or is shaded, the whole system is affected. Because of this, a parallel circuit is much more suitable for our (and most) situations.

In a parallel circuit, the components are wired ‘parallel’ to each other, meaning all the positive wires connect together and the same with the negative wires. Parallel wiring of solar panels means the total voltage remains the same, but the amount of amps or power is doubled. EG 2 x solar panels with a voltage of 12v and an output of 5 amps wired in PARALLED will generate 10 amps of power at 12v. It also means that if one panel is shaded or damaged, it wont affect the other panel. Our whole electrical system (excluding the output from the inverter) is 12vdc so wiring our panels in parallel was the right way to go! To achieve this we needed some simple Solar ‘Y’ Connectors that joined the two positives into one, and same the the negative wires.

We plugged the cables from the panels into the Y connectors, then plugged the extension cables into the output end (after covering the exposed end of the extension cable with electrical tape). We could now run the wires inside the van and down to our battery bay. To do this we simply drilled some holes in a hidden part of our fiberglass roof, threaded the cables through and applied a hell of a lot of silicone to seal up the hole. For a more professional look, you can purchase a Solar Junction Box/Entry Gland which provides a waterproof entry point through the roof of the vehicle. Quick note - when running wires through holes in a metal surface, make sure you add a rubber grommet or something similar to prevent the exposed metal from rubbing through the wires.

Step 3: Installing the DC-DC Charger

Before using our battery to power any appliances, we need to make sure it can be charged properly. Time to look at wiring up the DC-DC Charger to get power into the battery and keep it topped up! The DC-DC charger has a fair few wires coming from the unit, so it’s just a matter of slowly working through the instruction manual and connecting everything in the correct sequence.

First job is to mount the controller in the desired location, ensuring enough room on every side for it to keep cool. The next step is to connect the small orange wire to select the charging profile. This wire determines the maximum voltage output from the charger and can be connected to various locations to achieve different max voltages. The default setting and the option we went with was to leave this disconnected, meaning the maximum voltage wont exceed 14.6v - this is perfect for our battery’s specifications.

The next wire to connect (or not lol) is the blue wire that triggers the unit to charge the second battery once the main battery reaches a certain voltage. This wire isn’t required for old vehicles with standard alternators like ours, but if you have a newer vehicle (generally 2005 and newer) your alternator might have a variable output, so this wire is needed. Check out Redarc’s website to find out if this is needed for your vehicle!

That’s it for the smaller wires from the unit for us! As we said, these are used based on your vehicle and battery type so aren’t applicable for every install. Now we can look at connecting the larger wires that control the vehicle & solar inputs, as well as the charger output and ground cables. As these are larger cables that carry a lot of current, proper joiners and connection methods need to be used to ensure a safe electrical connection. Redarc recommend using a soldered butt splice crimp that is covered with a heat shrink. This method gives the connection a good mechanical hold through the crimping, but also provides a solid electrical connection due to the soldering. This is recommended for ALL heavy duty cables - DO NOT USE the small coloured connectors as they are not rated for the wire size or current flowing through. These are for low current 12v applications only!

The first of the large wires to be connected is the ground wire (always a good idea to connect this first for most components). We extended this to make it long enough to reach where our second battery connected to the vehicle chassis, and bolted it down using a Heavy Duty Ring Terminal. Next was to connect the brown wire to the positive terminal of our second battery. As this is supplying power from the charger to the battery, it is extremely important to install a fuse here to protect the battery in the event of the charger malfunctioning. We ran the brown wire into one side of a 60a fuse (as recommended), then out the other side and off to the positive terminal of the second battery.

The two final wires bring the power into the unit, and are the last steps to wiring up our DC-DC charger. Phew! Remember the wires from the solar panels we ran in from the roof? Well it’s time to use them! Grab the positive solar wire and put a ring terminal on the end as below. Do the same with the yellow wire from the charger and attach these to each side of a heavy duty cutoff switch. We mounted the switch on the back wall of the battery bay so it’s easily accessed in an emergency. Take the negative solar wire and ground this on the vehicle chassis. Now finally connect the thick red wire from the charger, through another 60a fuse, to the positive terminal of the main/driving battery.

There you have it! The DC-DC charger should be all hooked up and completely functional! The battery should be charging from the solar panels straight away, assuming it’s day time and you’re outside haha!

To check the alternator is charging your second battery properly, attach a multimeter to the battery terminals and turn the vehicle on. You should see the voltage on the multimeter increase to approx 14.6v - don’t be alarmed if it doesn’t charge straight away. The main battery needs to reach a certain voltage before the charger will push power to the second battery.

Step 4: Installing the Inverter

This should be an absolute breeze after all the work done for the other components! Inverters generally only require a positive and negative wire to be connected for them to operate. Low power units may come with simple crocodile clips that connect to the terminals of the second battery. The beefier units, like our Redarc 700w Pure SIne Wave Inverter, are capable of outputting a lot of power so require a more solid connection. We ran a thick positive wire through a 125a Mega Fuse and then connected it to the positive terminal of the battery. A thick negative wire goes straight from the inverter to the negative battery terminal and voila, we have mains power in our campervan! As inverters are usually mounted out of the way and out of sight, they often have an optional remote switch so it can be turned on without digging around in cabinets or under beds. We mounted ours in the wall near the battery bay and simply plugged it into the appropriate socket in the back of the inverter for it to work!

Step 5A: Wiring to 12v Components - Our process

Now this is a step that we did a little different to most because of our existing setup. We think it’s important to give you as much info as possible to help with every aspect of your build so we’ll let you know what we did, as well as how it’s usually done!

So, our build. Because our little van was an existing camper, we already had a small secondary battery that charged off the alternator. This was already wired up to power the fridge, lights and water pump. It worked okay, but the battery is waaay too small to run the fridge off grid for more than a day without the vehicle needing to be turned on. We decided to keep this battery and leave the lights and water pump connected to it. We also brought a USB port that we connected up as well. These components don’t draw much power and are not used for most of the day, so they were fine to leave on the small existing battery. The whole point of installing our new electrical setup was to be able to run the fridge and charge our laptops without the need to turn the van on.

We pulled all the cupboard internals out to access the existing switch panel and fridge wiring, then we cut the positive and negative wires from the back of the fridge (leaving enough length to make the connections easy). We could have tried to figure out exactly how it was connected and unplugged and reused the wires, but it was honestly much easier to wire it from scratch than to figure our the 30 year old tangle of original stuff. We used some Twin Core 12v cable to rewire the positive and negative wires from the fridge to the new second battery. The positive wire needed to now go to a switch so we can turn the fridge off when needed. We ran the positive out of the fridge to one blade on a Waterproof Push Switch that we mounted in the bench top, then attached the positive of our new twin core cable to the other blade on the switch. All that was needed now was to join the negative fridge wire to the negative on our twin core cable and we could put all our cupboards back in!

The new cable could now run to the new secondary battery and be connected up to finish the fridge rewiring. The negative went to our common negative bus bar. The positive needed to be connected to the positive terminal on the second battery, but what do we need in between? That’s right, a FUUUSE! We purchased a simple Inline Fuse Holder and 5A Blade Fuse that connected to the the positive wire, and then to the second battery.

Step 5B: Wiring to 12V Components - The Normal Process

Now if you don’t have any electrical components in your van and are starting the system from scratch, this is what you’d usually need to run all your 12V electrical components. As you’re hopefully aware by now, you can’t just connect things up straight to the terminals of your battery and be good to go. There needs to be fuses in all of the circuits (each component is basically it’s own circuit) to protect the components and yourselves. With multiple circuits all running to one point on the battery, it’d be bloody messy untidy to have an inline fuse like we mentioned above for everything. This is where 12V Blade Fuse Holder’s come in handy for keeping everything clean and tangle free!

These fuse holders have a large nut where a thick positive wires runs to the positive terminal of the battery - this the common power for each of the fuses. From there, you can simply run your positive wires from each electrical component through their switches, and then to each of the blade connectors. Then it’s a matter of inserting the correctly rated fuses (see the components spec sheets) into the holder and all the ‘power’ wires for each component are done! The negative wires for each component can then run to the common negative bus bar that is already connected to the secondary battery, which is also earthed to the vehicle chassis. This completes the electrical circuits and you should be fully powered with a 12v electrical system!

If you’re wanting to keep it super simple, you can purchase an All in One Fuse & Switch Panel. This makes everything nice and simple and keeps all your fuses, positive wire connections and switches all in one place. If anything stops working, only having to look in one easy to reach spot makes it a lot less of a headache! All you need to do is run positive and negative wires from the respective battery terminals to the back of the switch panel, then plug your positive wires from the 12v components into the back of the panel as well. That’s it! Each switch has a preset fuse in the back so choose one that will suit the components best. You can also replace these fuses with one rated to better suit your components.

Step 6: Battery Monitoring

A very important and easily overlooked part of the process! With all the components tucked away out of sight, it’s important to know that everything is working as it should without the need to stick your head in for a look every few hours. This is a simple step that ensures you’re looking after the health of your second battery to get the most life out of it. Firstly, check out the chart below to give you an idea of what the voltage means in relation to how full the battery is. Keep in mind that AGM batteries can only be discharged to 50% or they just wont last. If you’re using a different battery type or for example you have a 24v battery bank, have a quick Google to familiarise yourself with the correct voltages for your setup.

It’s nice and straight forward to hook up a voltage gauge to your second battery to keep an eye on it’s levels. If you purchased a switch panel with a built in volt readout then you’re already sorted! You can purchase these little gauges separately and can simply wire them straight to the terminals of the second battery. Mount it somewhere you can see easily and you’re good to go! We chose to use Redarc’s 52mm Voltage Gauge because it looks A LOT nicer than the standard LED displays. These are usually mounted up on the dashboard to give the driver an idea of what is happening under the hood - we’d prefer to be able to see the battery levels while in the back using our devices, so had to get a little creative in order to get the gauge to work for our setup.

We connected the brown wire through a 2A fuse to the positive battery terminal. The black ground wire went to where we connected our other earth wires to the chassis. The orange wire meant for the ignition barrel was also wired to the positive battery terminal though a 2A fuse - this meant the unit has continuous power and would always display the battery voltage. Perfect for our setup! We now had an operational gauge that was showing the voltage of our second battery. This gauge also has the option of showing the current/amps flowing through any chosen wire with the optional Hall Effect Sensor. This sensor is great for telling you how much power/amps your solar panels are pulling in, or how much power your electrical components are using. We chose to run the positive wire from the solar panels through the sensor to see how well they worked. We continuously pull in 14A on a clear day which is more than enough to charge the battery as well as run every electrical item in the van!

Step 7: That’s A Wrap!

That’s it team, we’re done. Clear out all the tools and rubbish. Time to stand back and admire all your hard work!

Now’s a good time to go through and double check all your important connections. Give the wires a little wiggle/pull to make sure they’re not going to come loose any time soon. Use Cable Ties & Tidies to keep all your wires neat and out of the way and YOU’RE DONE!!!

It’s an absolutely amazing feeling completing an electrical setup and being able to power your life off grid! We really hope this guide to our setup has given you the information and confidence to jump into your own build. We certainly had a lot of questions when we first started and tried our best to answer those with this write up. If there’s something we’ve missed or you have a question specific to your setup, drop us a message and we’ll see if we can help!

Before you go…

How To Build A Roof Deck For Your Campervan For Under $400

How We Turned A School Bus Into A Tiny Home