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Australia How to install an off-grid solar system in your car successful?

How to install an off-grid solar system in your car successful?

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This post is also available in: Nederlands

I remember one night from our Van Life adventure so well, it was a night I didn’t sleep for a second. We parked on a free campsite along the road and a huge, supersonic, good-looking caravan parked next to us. Kind of impressed we stared out of the window.

This feeling of being impressed only lasted for a couple of seconds. A man came out of the trailer and the first thing he did was turning on the generator. Oh, men what a noise! Out of a sudden, our peaceful campsite turned into a noisy parking place.

We are so happy we have an off-grid solar system installed in our Van. It is better for the environment, easy to use and so much better for your own and others rest!

It is amazing to be independent of any other power source than your own when you are on the road. No need to go to a campsite or hostel to charge your stuff. With a solar electricity system, you can charge your electric devices and run a fridge 24/7. You can also turn the lights on without being afraid your car won’t start again in the morning!

So, do you want to install solar energy in your car? This blog will explain exactly what you need and how to install it in your car. It will be a bit technical, but we’ll try to explain everything as clear as possible by using easy language. This makes it understandable for everyone.

How to install an off-grid solar system?

Introduction to Sun Solar

The sun is shining every day. On a cloudy day, you might not see the sun, but I assure you it’s there! The sun is a beautiful source to gain electricity and an off-grid solar system makes it so easy to use it!

There are multiple options for such a system. You can use a camping solar panel, which is foldable. When you are driving this solar panel is in your car and as soon as you stop, you can unfold it, lay it outside in the sun and it will give you electricity.

This blog is about installing a fixed solar panel to the roof of your car/Van/4×4/camper etc. You install it once and it works every day. The solar panel charges batteries, which you can use any time of the day (also during the night, when the sun isn’t shining).

Check your car thoroughly before you decide to buy it

Before you install the off-grid solar system, you have to figure out how much energy you need, how many solar panels you need to provide that energy and how big your batteries need to be to store that energy.

So first, check out how much energy, so how many amperes you need!

Calculating the Amperes you need

Before you start looking around for your necessities, you should know what you need. And to know what you need you should lead everything back to the base unit of electric current: Ampere.

This means that you have to figure out how many Amperes (shortened as Amps) you need for your electrical needs. This is probably a lot easier than you expect right now, as the Amps are mentioned on every device!

Solar Panel arrived

Most of the time the Amps are mentioned directly on the device, but sometimes you have to calculate them with other given information like Watts and Volts. We’ll give you an example:

The charger of Kelly’s laptop mentions the following details:

  • Input: 100-240V – 1,5A
  • Output: 20V – 2,25A

Always check the input, as this is the power it costs to charge your device. So, Kelly’s laptop uses 1,5A per hour when it is charging.

When there is only Watts (W) and Volts (V) mentioned on your device you can calculate the amperes (A). The amperes (A) is equal to the power (W) divided by the voltage (V):

TIP: Use the following formula to calculate the amperes your device is using
A (Amperes) = W (Watts) / V (Volt)

Step 1: Calculate the Amperes of your devices

Figure out how many Amps your devices use when you charge and or use them.

For example:

  • Laptop (2x): 1,5A + 1A = 2,5A
  • Phone (2x): 0,5A + 1A = 1,5A
  • Photo camera (2 batteries charger): 2,1A
  • GoPro Hero 5 Black: 1,2A
  • GPS Smart Watch: 1A
  • Rechargeable battery charger: 2,1A
  • Camping fridge: 3,5A
  • Inverter: 15A

Step 2: Figure out how long you use the devices

Figure out how long you want to use/charge your devices per day. This is important to know how much energy you like to gain from your off-grid solar system. Take an average over a week or so.

Like, we don’t charge our GoPro daily, but probably twice a week. A full charge takes about two hours. This means on an average daily basis we charge the GoPro for 30 minutes.

For example:

  • Laptop (2x): see the inverter
  • Phone (2x): 1,5h + 1,5h = 3 hours
  • Photo Camera (2 batteries charger): 15 minutes
  • GoPro Hero 5 Black: 30 minutes
  • GPS SmartWatch: 10 minutes
  • Rechargeable battery charger: 30 minutes
  • Camping fridge: 24 hours
  • Inverter: 3 hours

Step 3: Do the maths for your off-grid solar system

Calculate how many amperes you need for off-grid solar system

Check how many amps you need on average in 24 hours.

For example:

  • Laptop (2x): see inverter
  • Phone (2x): 1,5A x 3 hours = 4,5A
  • Photo camera (2 batteries charger): 2,1A x 0,25h = 0,5A
  • GoPro Hero 5 Black: 2,1A x 0,5 = 1A
  • GPS Smart Watch: 0,2A
  • Rechargeable battery charger: 2,1A x 0,5 = 1A
  • Camping fridge: 3,5 x 24h = 84A
  • Inverter: 15A x 3h = 45A

Total: 4,5A + 0,5A + 1A + 0,2A + 1A + 84A + 45A = 136,2A

So, this means you are going to use about 136,2A per day. The one day it would be a bit more and another day a bit less. Make sure your batteries are big enough to charge with at least 136,2 A.

TIP: You can also use a solar energy calculator. Fill in the details from the devices you want to use and charge and it will calculate the rest for you.

Suitable batteries for off-grid solar systems

There are many different types of batteries available and for a solar energy system, you need a deep cycle battery. They aren’t cheap, but they are good. Deep cycle means that you can use all their energy and recharge them from zero. Over and over again.

You can’t do this with a normal car battery. A car battery is used to give peak power when you start up and charge right after. It is not good to flatten this kind of battery (for example when you forget to switch off your lights). The more often you do this, the worse it gets. While a deep cycle battery can handle this with ease.

How big your battery should be, depends on your power needs. If you only want to charge some phones and cameras you need a small one. You just calculated your electrical needs in Amps, so make sure the battery is able to carry at least that amount of Amps. Always make sure you have a bit extra, to make sure you don’t run out of power when you use more energy than expected.

TIP: You can connect two smaller batteries together, to let them function as one big battery.

We bought two 105A batteries. By connecting them parallel to each other they act as one big battery of 210A. On a daily base, we use the energy to run the fridge 24h, charge both of our laptops at least one time with the inverter. And we charge different smaller devices like phones and action cams.

Suitable solar panels for off-grid solar systems

Now you know how big of a battery you need, your solar panels need to provide enough energy to charge the batteries to keep your off-grid solar system up and running. There are many different types of solar panels available. We’ll explain the 3 most common ones below.

Poly Crystalline panels

Poly Crystalline Solar Panel
Poly Crystalline Solar Panel

The Poly Crystalline panels are the most popular around the world. The pros of these panels include:

  • They are cost-effective
  • They have a high-temperature co-efficiency.

The cons of these panels include:

  • Not real high energy conversion
  • The panels are quite large, so they tend to take up more space.

Thin-Film panels

Thin Film Solar Panel
Thin Film Solar Panel

The Thin-Film panels have versatility in usage but are probably not the best panels for on your car. The pros of these panels are:

  • Low costs
  • They also function well in shaded areas

The cons of those panels include:

  • They are very big- They have a low energy output
  • They have a faster rate of degradation

Monocrystalline solar panels

Monocrystalline Solar Panel
Monocrystalline Solar Panel

Monocrystalline Solar Panels are one of the oldest and most reliable panels. The pros of these panels are:

  • Long-lasting
  • Resistant for high temperatures
  • They have a high electricity conversion.

The cons include:

  • High start-up costs
  • They are quite fragile

NOTE: We bought a flexible monocrystalline solar panel. It wasn’t very expensive and the flexible ones seem to be less fragile. So, both of these cons can be revised after our experiences.

How many Watts should your solar panel be?

How many Watts your Solar Panel should be, depends on your power needs. The more power you use, the more power you should generate. If we go back to the batteries we have (210 A), we need a solar panel that is able to provide at least 210A a day.

We have a 250W, 18V flexible monocrystalline solar panel. This solar panel is able to provide 14A an hour.

NOTE: There do not exist 12V solar panels! It might be promoted as a 12V Solar Panel, but always check the output voltage, to calculate the Amperes.

We have a 210 A battery. 210 A / 14 A = 15 hours. This means it will take up to 15 very sunny hours, to fully charge the batteries. This will approximately be 2 to 2,5 days. It will even take longer if we use energy from the batteries in the meantime.

You might already get it. Our solar panel does not provide enough energy to meet our energy needs. Though, we are barely ever running out of energy. How is that possible?

Solar Panel for on the Van

Multiple charging options for your battery

Instead of only using a solar panel to charge our batteries, we also installed a dual battery kit in our car. This means that the generated energy from a driving car is stored in our deep cycle batteries as well.

The solar panel and the dual battery kit provide more than enough energy to meet our energy needs. And if we don’t drive for a couple of days, our batteries have enough storage.

On average we only use 136,2 Amps a day, while our batteries contain 210 Amps. The solar panel provides us about 100 Amps a day. So we can camp around 4 to 5 days before we are running out of energy. For us, this is normally more than enough.

TIP: It might be more efficient to invest in a dual battery kit than in an extra solar panel that you have to place somewhere.

Dual battery kit

A dual battery kit is an extra option for an off-grid solar system. You don’t need to have this, to make your system work, it just helps your batteries to charge when you are driving.

Dual Battery Kit for off-grid solar system
Dual Battery Kit

It won’t take any energy from your car battery. It only charges the deep cycle batteries when the car battery is fully charged. So, you don’t have to be afraid that you ruin your car battery with the dual battery kit.

And when you switch off the car engine, the dual battery kit will stop charging the deep cycle battery. So, your car battery won’t run flat.

It does work the other way around as well. If your car battery runs flat because you forgot to switch off your lights, you can charge your car battery with the deep cycle battery.

For us, this is a very helpful tool, as we are using quite a lot of energy. Sometimes the solar panel doesn’t provide enough power to keep the batteries charged. We are driving anyway, so then we can charge the deep cycle batteries as well.

What else do you need for your off-grid solar system?

I’ve explained everything about the battery, solar panel, and dual battery kit. But you need a couple of more things to make it all happen.

Solar Charge Controller for off-grid solar system
Solar Charge Controller

Solar Charge Controller

A solar charge controller is a little device that regulates the power from the solar panel into the batteries. An important function is giving the batteries as long as a life as possible. You need this device to protect your batteries from overcharging.

If you buy a Solar Charge Controller with a screen, you are able to check your off-grid solar system. You can see how much energy you use and how much energy the solar panel is providing.

12V adapter

12V socket with battery clamps
12V socket with battery clamps

The batteries provide 12V, which is the same Voltage that comes from the cigarette lighter in your car. You can use this to plug in USB ports to charge most of your smaller devices. If you use a camping fridge, this device is also able to run on 12V.

But, you can’t put a USB into your battery, so you need a little hub. This is a 12V adapter with clamps on the end of the positive and negative wire. You can clamp these onto the battery and put a USB adapter in it.

The big advantage of using the 12V as a power source is that you only use the Amps of the device you are charging. If you need 240V, you need an inverter, which normally uses a lot more power.


To charge or use some devices you need 240V. For example a laptop or television. As your batteries only provide 12V, you need an inverter to convert this power into 240V.

An inverter is not necessary for your system to let it work. It is just an extra option if you want to generate 240V.

It costs a lot of power to convert this energy. So, always turn your inverter off when you don’t use it. Even if you don’t plug in anything to your inverter, it will still use energy to convert the power.

Different types of inverters

There are two different types of inverters:

  • Pure Sine Wave: Provides clean energy and it allows you to run devices safely, even when they are sensitive. Like laptops.
  • Modified Sine Wave: The older ones provided quite bad energy, but the newer ones aren’t too bad anymore. You can use this kind of inverter for devices that don’t have sensitive electronics, like fridges and televisions.
Pure Sine Inverter 600W with battery clamps for off-grid solar system
Pure Sine Inverter 600 W with battery clamps

So, if you need an inverter, and if so, the type of inverter you need in your off-grid solar system depends on the type of device you want to run on it. Do you want to charge your laptop or other sensitive electronics? Go for a Pure Sine Wave inverter. This type of inverter is a bit more expensive than a Modified Sine Wave inverter, but it will protect your devices for overcharging.

How big your inverter should be, depends on the Watts. So, instead of looking at the amperes, we are going to look at the Watts now.

As an example we take Kelly’s laptop again, these were the details:

  • Input: 100-240V-1,5A
  • Output: 20V-2,25A

This time you have to check the output. Her laptop is using 20V x 2,25A = 45W. So, if we want to charge Kelly’s laptop, we need an inverter of at least 45 Watts.

TIP: Make sure you know what kind of devices you want to run on the inverter, before deciding on what kind of inverter you need and how big it should be.

A blender uses about 500 Watts and a hairdryer between 800 and 2400 Watts. You can always find this information on the product itself.

Small versus big inverters

150W can inverter with 12V plug
150W can inverter with 12V plug

The smaller inverters (up to 150W) have a 12V plug. So you can plug this inverter into a cigarette lighter or the 12V adapter we spoke earlier about.

The bigger inverters need to be attached directly to the battery. The positive pole of the inverter goes to the positive pole of the battery. Same for the negative sides.

The bigger the inverter, the more Watts it can handle, the more energy it will use to convert power. So, get an inverter that suits your needs, but not bigger. It will only take your valuable energy away.

OUR EXPERIENCE: We have two inverters. One is a smaller one, of 150 Watts. It uses about 15 Amps an hour and we are able to plug into the 12V adapter. We can charge both our laptops at the same time with this inverter.

The other inverter we have is a bigger one of 600 Watts and uses 40 Amps an hour! This is quite a lot of energy, so we only turn it on for a couple of minutes when we want to use the blender or mixer.

Installing the off-grid solar system

Everything you use has a negative and a positive pole. The negative pole is black and the positive one is red.

Like in the image below, this is which devices you should connect to each other in your off-grid solar system:

  • Solar Panel with Solar Charge Controller
  • Solar Charge controller with Deep Cycle Battery
  • Deep Cycle Battery with Car Battery (only do this if you have a dual battery kit!)
  • Deep Cycle Battery with the inverter
  • Deep Cycle Battery with the 12V adapter


Once it is all connected, you are totally ready to go camping! So, let’s go!

camping australia

How much does it cost to install an off-grid solar system in your car?

It is not possible to give you the exact amount you need to install an off-grid solar system in your car. This is because it all depends on how much energy you need and how extended you would like to have your system.

It also depends on where you would like to install it. We bought and converted our Camper Van in Australia, but the prices might be totally different in the United States.

Still, we would like to give you a little bit of an idea. The list below is everything we bought for our solar energy system with the costs we spent on it. Prices are in Australian Dollars.

  • 250W, 12V Flexible, super thin, Solar Panel: $229
  • 12V, 125A Dual Battery Kit: $129
  • Solar Charge Controller 12V/24V 15A: $149
  • Pure Sine Inverter 600W (1500W Surge) 12VDC/230VAC: $80
  • 12V, 150W Can inverter: $60
  • 2x Deep Cycle Battery 12V, 105A: $458
  • 12V socket with battery clamps: $9
  • 12V splitter 4-way: $20
  • Extra cables: $20
  • Iron screws (to mount the solar panel to the roof): $10
  • Duct tape (to extra mount the solar panel to the roof): $15
  • Little bits and pieces (small accessories): $50
  • Total: $1229 (€760 / US$865)

Solar Panel on top of our Van


Using solar energy for an off-grid solar system is a beautiful solution to generate electricity when you make a road trip. It is good for the environment, doesn’t make noise and it is easy to use.

Check how much amperes your devices are using and for how long you want to use or charge them. This information will help you to decide how big your battery and solar panel need to be.

Collect all the items you need and connect them with each other. Here is one more time on a row what you need to install a solar energy system in your car:

  • Solar Panel(s)
  • Deep cycle battery (or more)
  • 12V plug with battery clamps
  • Solar Charge controller
  • 12V splitter
  • Extra wires
  • 12V USB plug/splitter
  • Possibly an inverter
  • Possibly a dual battery kit

Useful tips

In the beginning, we made some mistakes with our energy. As a result, we ran out of energy and we burnt several fuses. This is what can happen if you use a limited power source.

To use the energy the sun provides you as optimal as possible, here are some handy tips:

  • Only plug-in devices that really need energy. As soon as you don’t use your devices or if they are fully charged, unplug them.
  • Only turn on your inverter when you need to use 240V
  • Park your car in the sun, so the solar panels can charge the batteries as much as possible.
  • Switch devices off when you don’t need them to save their energy and charge less.

If you want to get the most out of your solar panel, check out our blog post Best time to travel Australia: An overview per region, where we explain how to travel around Australia while only having summer and lots of sunshine!

We love to hear from you!

Hopefully, this blog post was useful to you, so you are able to install your own solar electricity system in your car. Did you also install solar energy on the roof of your car? Or do you have any further questions? Leave a comment below! If you are totally ready to rock and roll your road trip, check out what to explore in Australia!

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Kelly Kap
Living the dream is my motto! I like outdoor adventure, volunteering, nature, exploring new cultures! I'm always seeking new challenges and new places to discover. Travelling was always my biggest passion since I was a kid! I like to inspire people to stop dreaming and start living their dreams!



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