How Do You Size Solar For Your Off-Grid Vehicle?

Whether you’re looking to make the most out of your weekend getaways or you’re planning to turn your van into your permanent home, adding solar panels to your set-up is the perfect way to take your vehicle off-grid.

Adding an auxiliary battery is essential for off-grid travel, so integrating solar panels into your set-up is a cost-effective and efficient way to ensure your batteries stay charged on your adventures. However, ensuring that you have enough solar to keep you powered is an important consideration before purchasing panels. Follow our easy steps below to calculate how much solar power you will need for your caravan, camper or 4WD.

Read More: Calculating Battery Size for Your Caravan or 4WD 

Solar Size Calculator

Figuring out how much solar you will need for your set-up is fairly simple. The following equation can be used to calculate the watts you need:

 In this blog, we will be explaining in further detail how to use the equation.

Work Out Your Daily Load

Firstly, you’ll need to have a look through your set-up and make note of the power that you will need while you’re travelling.

You’ll need to make a list of everything that needs to be powered, and its load draw. The load draw for an appliance or device is expressed in either Amps or Watts, and this can usually be found on the label, packaging or website listing for the product.

If the device has a load draw shown in Watts, you can simply divide the Watts by the device’s voltage to convert the load to Amps.

If the device has a load draw shown in Amps, or you’ve converted the load draw to Amps, you can multiply the device’s Amps rating by the number of hours it will be used each day.

The resulting figure will give you the Amp-hour (Ah) requirement for that device. Repeat this for all your appliances and devices. Then, simply add up all the daily Ah requirements to determine your total daily energy load.

Determine Your Battery Voltage

This step is pretty simple. You’ll need to look at your auxiliary battery and confirm if it’s a 12V or 24V battery. Note down the battery’s voltage.

Calculate the Watts Required for Battery Charging

Next, you’ll need to figure out how many Watts are required to charge your battery and cover your daily load. 

To do this, you’ll need to multiply your daily load by your battery voltage. For example, if your daily load is 200Ah and your battery voltage is 12V, you can multiply them together to determine your required Watts is 2400, as shown in the example below:

Divide Your Required Watts by Average Sunlight Hours

Once you’ve worked out the Watts needed for your battery and load, we recommend you divide this by the peak sunlight hours you’ll receive. In Queensland, we receive 4.2 hours per day of peak sunlight, but when calculating your solar size, we recommend averaging the peak sunlight to 3.5hrs.

This is a somewhat conservative figure, but it’s important to remember that it’s quite likely your caravan, camper or 4WD will be parked in a shaded area, so you might not be utilising the full 4.2 hours of peak sunlight every day. If you’re planning to travel to other Australian states, it’s also worth considering that the peak sunlight hours could be different.

So, once you have divided your Watts by 3.5 hours, you’ll be left with the ideal solar size for your setup:

Better to be Safe, Than Sorry

When it comes to sizing your solar for your set-up, our biggest recommendation is that it’s better to oversize than undersize.

We recommend installing the biggest system you can fit on your roof, within your budget, as it will never hurt to have more solar… but it can leave you stranded if you don’t have enough. 

Without adequate solar on your off-grid vehicle, you could be left with no way to charge your batteries sufficiently. Efficiently charging your batteries regularly with solar also benefits the batteries, prolonging the longevity of your auxiliary battery. 

Including solar panels in your set-up can completely change the way you travel, allowing you to go off-grid for longer and travel further - but only if you do it right. It’s important to properly calculate how much solar you will need before you purchase panels, so you can get it right the first time.

Read More: Benefits of a caravan solar system

Springers Solar | Your Trusted 12V/24V Components & Accessories Supplier

We only stock the best brands in the extra-low voltage industry for the best prices - you can trust that when you buy gear from Springers, you are setting up your system to perform long-term. We don't waste our time or your time with low-quality products. 

With an in-house team of 12V/24V experts, we can offer advice and support as you set up your off-grid, off-road, or DIY battery system. We are Queensland-based and house our stock, so check out our online store here or visit us at Lawnton or Capalaba for in-store help.