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How To Install An Off-Grid Solar System In Your Car Successfully?


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Having your own tiny house on wheels is freedom. If you also have your own off-grid solar system in there, it makes the feeling of freedom even more so!

In this blog, we will explain what you need for solar energy and how to install it. This blog will be a bit technical, but we’ll try to explain it as clear as possible in easy language, so it is understandable for everyone.

It is just amazing to have an independent power source on a campsite or whatever you are traveling with. With a solar panel, you can charge your phone, laptop, and camera anywhere you want!

So, if you bought your car in Australia and want to install solar energy, keep on reading!

It’s all about the Amperes

Before you start looking for solar panels, batteries and inverters, you should know what kind of solar panel and batteries you need, as there are many different types available. To get to know what kind you need, you should figure out how many Amperes you need. An Ampere, often shortened as Amp, is the base unit of electric current. 

On every electric device, the Amps are mentioned. Most of the time directly, sometimes only Watts and Volts are mentioned. We’ll give you an example:

On the charger of Kelly’s laptop are mentioned 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 current (A). The current (A) is equal to the power (W) divided by the voltage (V): A=W/V

How to calculate the amount of amperes you need

Step 1: Figure out how many amperes you need

Figure out how many Amps your devices use when you charge them. Most of the time it is mentioned on the charger of your device.

For example:

  • Laptop (2x): 1,5A + 1A = 2,5A
  • Phone (2x): 0,5A + 1A = 1,5A
  • Canon EOS 750D (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 want to use/charge your devices per day.

Check for yourself how long each device takes to fully charge or how long you want to use it per day.

For example:

  • Laptop (2x): see inverter
  • Phone (2x): 1,5h + 1,5h = 3 hours
  • Canon EOS 750D (2 batteries charger): 15 minutes
  • GoPro Hero 5 Black: 30 minutes
  • GPS Smart Watch: 10 minutes
  • Rechargeable battery charger: 30 minutes 
  • Camping fridge: 24h
  • Inverter: 3 hours

Step 3: Check how many amps you need in an average 24 hours

Multiply the amount of Amperes with the time you want to charge or use the device.

For example:

  • Laptop (2x): see inverter
  • Phone (2x): 1,5A x 3 hours = 4,5A
  • Canon EOS 750D (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

Step 4: Make sure you have enough electricity

You now know you are going to use about 136,2A per day. Sometimes it may be a bit more and other days a bit less.

To make sure you have enough electricity you can use, check out one of the many online available solar energy calculators. If you fill in your needs, the calculator will do the rest. It shows you how big your solar panel should be and how big the capacity of your batteries should be.

Batteries for an off-grid solar system


There are different types of batteries available. For an off-grid 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 easily over and over again.

You can’t do this with a normal car battery. A car battery is used to giving peak power when you start up and charge right after. It is just not good to flatten the 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 easily.

How big your battery should depend on your power needs. If you just want to charge some phones and camera’s, you only need a small one. We have our fridge running 24/7, charge our laptops via the inverter daily, sometimes even multiple times a day, and also charge some smaller devices. For this, we bought two 105A batteries. By connecting them to each other they act like one big battery of 210A.

Solar panels for off-grid solar systems

Left: Thin-Film panels | Middle: Poly Crystalline panels | Right: mono crystalline solar panel

There are different types of solar panels available, we’ll explain the 3 most common ones below:

Mono Crystalline panels

These solar panels are one of the oldest and most reliable solar panels to turn the power of the sun into energy that works for you. Their pros are that they include longevity, heat resistance and more electricity production.

The cons include high starting costs and the fragility of the panels. Although both these cons can be revised after our experiences. We bought a flexible mono crystalline solar panel on It wasn’t very expensive and the flexible ones seem to be less fragile, as they are flexible.

Poly Crystalline panels

These solar panels are the most popular around the world. The pros of these panels include costs-effectiveness and a high temperature co-efficiency.

The cons of these panels include less energy conversion and larger panels, which tend to take up more space.

Thin-Film panels

These panels have a versatility in usage but are probably not the best for panels on your camper van. The pros of these panels are the low costs and the function in shaded areas. 

The cons include that they require large amounts of space, a faster rate of degradation, and a low energy output.

How many Watts should your solar panel be?

This all depends on your power needs. The more power you use, the more power you should generate, the bigger your solar panel should be. You can check your needs with a solar energy calculator

We have a 250W flexible mono crystalline solar panel, which provides us enough energy for our needs.

What else do you need?

To connect the solar panel to your batteries, to provide power, you need a little bit more than just a solar panel and batteries. We’ll explain it a bit more with a diagram of how it is all connected with each other. Then we will explain all you need.

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

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 of power.


The inverter can be connected straight to the battery. If you turn this device on it will start using power, even if you don’t charge anything with it. So, make sure you only turn your inverter on if you actually need it. You probably need 240V if you want to charge your laptop or any other AC devices, like a television or blender. 

What kind of inverter you need for your off-grid solar system depends on the Watts your devices are using. As an example we can take Kelly’s laptop again, here are 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 just want to charge Kelly’s laptop, we need an inverter of at least 45 Watts.

A blender normally uses about 500Watts and a hairdryer between 800 and 2400 Watts. Make sure you know what kind of devices you want to run on the inverter, before deciding on what kind of inverter you need.

There are also inverters available that you can plug into a cigarette lighter. These normally aren’t that big (about 50W-150W), but you should be able to charge your laptop with it. Of course you also have to take care, as the more Watts your inverter is, the more power it uses.

We have two inverters. One we are able to plug into the cigarette lighter of 150 Watts and uses about 15A an hour. We can charge both of our laptops at the same time with this inverter.

If we want to use the blender or the mixer we use our big inverter of 600Watts. This one is connected straight to the battery and uses 40Amps an hour! This is quite a lot of energy, so we really only turn it on when it is necessary. 

Solar charge controller


A Solar Charge controller is a small device that guides the power from the solar panel into the batteries. An important function of this device is to make the batteries last as long as possible. You need this device to protect your batteries against overload.

If you buy a solar charge controller with a screen, you can also check your system. This way you can see how much energy is coming in and how much is being used.

12V adapter


The batteries provide 12V, which is the same voltage that comes from the cigarette lighter in your car. You can use a 12V adapter to install USB ports from your battery. This allows you to charge small devices, such as your phone and action cameras. If you use a camping refrigerator, this device can also run on 12V.

You cannot plug USB plugs directly into your battery and therefore you need a hub. This is a 12V adapter with terminals on the ends of the positive and negative wires. You put these clamps on the battery and you can plug in a USB adapter in the 12V output.

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

Dual battery kit


A dual battery kit is an extra option. You don’t need to have this, to make your system work, it just helps your batteries to charge quicker. A dual battery kit makes it possible to charge your deep cycle batteries with your car battery when you are driving. 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’ll ruin your car battery with the dual battery kit.

You simply connect a negative wire from the negative pole of your car battery to the negative pole of your deep cycle battery. The same you do with a positive wire from and to the positive poles. 

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

Installation of the off-grid Solar system


Time needed: 1 day.

Now you have everything you need to make the off grid solar panel work, it’s time to install it. Follow the next steps to make it work.

  1. Step 1

    Connect the wires of the solar panel to the solar charge controller

  2. Step 2

    Connect the solar charge controller to the battery

  3. Step 3

    Clamp the 12V adapter to the battery and possibly use a 12V splitter with USB ports

  4. Step 4

    Connect the inverter to the battery. Only switch the inverter on when you really need it, as it uses a lot of energy to convert 12V to 240V

  5. Step 5

    If you want to make use of the dual battery kit, connect the device to your car battery. Then connect the device to the deep cycle battery of your off-grid solar system.

  6. Step 6

    Enjoy the freedom!


So, one more time on a row what you need to install an off-grid solar system on your camper Van:

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

Useful tips for using your off-grid solar system

In the beginning, we made some mistakes with our energy, so we ended up running out of energy and we burnt several fuses. This is just what needs to happen to understand that you are using a limited power source.

You can avoid this by imlpementing the following tips:

  1. Only plug in devices in that really need energy. As soon as your devices are charged, unplug them.
  2. Only turn your inverter on when you need it.
  3. Park your car in the sun, so the solar panels can charge the batteries as much as possible.
  4. Switch devices off when you don’t need them to save their energy and charge less.

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6 thoughts on “How To Install An Off-Grid Solar System In Your Car Successfully?”

  1. To be honest your article is informative . I saw your site and I read it. I got some new information from here.
    It is beneficial for many more like me. Thank you so very much for such informative and useful content.

  2. It’s a great point that you should do research ahead of time to find out what solar panels and batteries you need. My sister is trying to get some new solar panels installed on her property this month because she likes the idea of being more eco-friendly. I think it’s a great idea to get panels on her camper as well so that she has her own water supply.

  3. hello, great stuff, thanks
    I like to know if somethings was done already
    like to buy a electric pickup truck and install an on board
    solar charging system so it charge all the time ( Island or Belize situation)
    some one as any idea?

  4. WOW!!! You saved my sanity! Thank you! I was not told that the inverter used energy even when there is no appliances connected, so I left it on 1all the time. I was going mad running out of energy all the time. God bless you

  5. So of I’m reading this right, if I have a refrigerator plugged into the solar panels, if the solar runs out of energy, it will start draining the car battery as well. Is that correct?

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