When installing a camper solar system, one of the first questions we must ourselves is, “How much solar do I need for my camper van? 100 watts? 300 watts? More?” This is a difficult question to answer accurately because everyone’s needs are different. What is the best solar size for one person may not be the best for you.
In truth, your ideal solar power size depends on your power requirements. The more power you intend to use in your camper van, the more solar you will need. The good news is that you don’t have to do any difficult calculations to identify how many watts of solar you need to install.
In this post, you can download our solar array size calculator. It’s a free resource that will help you identify the following pieces of information:
- Minimum solar wattage size
- Fuse & circuit breaker sizes
- Ideal solar wire sizes
- Solar charge controller size
Let our solar size calculator do all the work for you.
So if you’re ready, let’s dive into it!
Size Your Battery Bank
The calculations in our solar spreadsheet assumes you have a properly sized battery bank. If you just randomly bought a battery without taking into account the electrical devices in your camper van, the solar size calculator will not work for you.
Therefore, we strongly recommend download our leisure battery calculator first and taking the time to properly size your battery bank. To get started, read our leisure battery size calculator post.
1. Download Solar Calculator Spreadsheet
Download the free solar calculator to get started. The document is available in both Google Docs and Microsoft Excel file formats. (But the Google Docs version is better.)
To start calculating your ideal solar wattage, download our free spreadsheet. The document is available in both Google Docs and Microsoft Excel file formats. (The Google Docs version has a better user interface)
2. Read Pink Information Box & Delete
When you open the document, you will be met with an interface similar to the image below. Follow the directions in the pink text box and delete the box when you’re ready to begin.
If you opened the Google Docs version you need to make a copy of the document and save the file into your own Google Drive directory. If you don’t do this you won’t be able to edit the document.
If you opened the Microsoft Excel version you can start making edits right after opening.
3. Battery Bank Size (in Amp-hours)
In Step 1, you will need to fill in the two boxes shaded in green. They are:
- Battery bank size (Ah) – Here you will enter the size of your battery bank.
- Battery Type – Here you pick from the drop-down menu whether you are using AGM or lithium batteries.
It is worth repeating that it’s important to correctly size your battery bank before using our solar calculator. If you haven’t done so already, we provide a link in the document for you to click to download the battery spreadsheet.
4. Identify Minimum Recommended Solar Size
Once you have entered the information in Step 1, the solar calculator will determine, under Step 2, the MINIMUM solar wattage size that is appropriate for your van. If you haven’t completed the first step, there will be no value here.
Refer to the red box below, which outlines Step 2.
Essentially, solar calculator derives the minimum wattage recommendation based on the below information.
- If using lithium batteries: Recommended solar watts is a 1:1 ratio to Ah battery bank.
- If using AGM batteries: Recommended solar watts is a 1:2 ratio of Ah battery bank.
5. Finalize Your Own Solar Array Wattage Size
Next, based on the minimum wattage recommendation from Step 2, you will need to decide, in Step 3, how much solar you will actually install on your camper van. This is entirely up to you. However, we strongly recommend that you choose a total wattage that is equal to, or greater than, the minimum recommendation.
Refer to the red box below, which outlines Step 3.
To make the process easier, we recommend choosing a total solar wattage that is a multiple of 100, 160, 180, or 200. This is because these four sizes are the most widely available solar panels sizes on the market.
Lastly, it is perfectly OK to install more than the recommended minimum. A larger solar array means your batteries will recharge faster, which can be beneficial when parked for extended periods of time in shaded areas.
For more: Unbound Solar has a short, informative post on the effects of shade on solar panels.
6. Decide Number Of Solar Panels
In Step 4, you must enter how many solar panels you plan to install on your camper van. This is why, in Step 3, we recommend finalizing a solar array wattage that is a multiple of 100, 160, 180, or 200.
Refer to the red box below, which outlines Step 4.
Tip: Go for fewer but larger panels, if possible. And if possible, keep the total number of solar panels to not more than two. This will help to keep your wire size small and eliminate your need for solar in-line fuses.
7. Choose & Buy Solar Panels
Now that you know the amount of solar watts you will install AND how many solar panels you’ll have you are ready to purchase your panels.
In Step 5 we give our four recommended panels. All our recommended panels are manufactured with the newest ‘9BB’ technology, meaning that these are the panels with the highest efficiency when converting sunlight to power.
Refer to the red box below, which outlines Step 5.
Below we also list each of the four panels that we recommend in the solar calculator spreadsheet.
Though you might be ready to celebrate at this point the solar calculator isn’t done yet!
This powerful calculator can also help you identify all the correctly sized parts and components you’ll need to complete your DIY solar project. Keep going below to see how this works.
8. Enter Solar Panel Imp(A) and Max Series Fuse Rating
In Step 6 you will see two green-shaded boxes. Here you will need to enter the “Imp(A)” and “Maximum Series Fuse Rating” of only one of your solar panels. You can easily find this information on the backside of the solar panel or if you view the panel’s only sales page.
Refer to the red box below, which outlines Step 6.
Every single solar panel on the market today has slightly different information. So you need to know the information of your exact panels.
If you bought one of our four recommended panels, we include the Imp(A) and Max Series Fuse Rating information in the Blue-shaded box to the right, which is titled “Step 6 Recommendation”.
Otherwise, you can find your panel’s technical information sticker, which should look similar to the image below.
9. Decide Series Or Parallel Solar Panel Wiring
In Part 7, the last piece of information you need to decide is, if you have more than one solar panel, how you will be wiring the panels together. You can wiring the panels together either in series or in parallel. If you are unsure, check out our series vs. parallel post to learn more.
If you only have one solar panel, select “Series”.
Refer to the red box below, which outlines Step 7.
Tip: If you have only two solar panels to connect, select “Parallel”. If you have three or more panels, select “Series”. This is because although parallel wiring is more beneficial, it because much more complicated and risky (higher amperage) to do parallel wiring with 3+ panels.
10. View Calculator Summary Table
This is the best part of the camper van solar calculator.
Once you have filled out all the green-shaded cells, the summary table at the bottom will help you to select all the tiny parts and components that you’ll need to complete the solar wiring project. This includes:
- Fuses & circuit breakers
- Charge Controllers
- Branch connectors
All recommended products will be appropriately sized for your unique solar system.
Refer to the red box below.
In the “Parts Size” column, you can click each of the individual products to purchase them on Amazon.
11. Download Solar Wiring eBook
Lastly, each item listed in the summary table has a part #. To make use of these part numbers, download our solar wiring eBook. The eBook has informative solar wiring diagrams.
The part numbers in this table correspond to the part numbers in the wiring diagrams so that you can see where each part needs to be installed so that you can complete your solar project.
Refer to the red boxes and arrows below.
Every solar component in the calculator summary table has a “Part #”, listed in Column D. For example, the solar charge controller is part #16.
To identify where to install each component, download our solar wiring eBook and locate each product number in the solar wiring diagrams.
Interested In The MOST Efficient (9BB) Solar Panels?
“9BB” solar panels are becoming the next big thing in the solar panel industry. Read our 9BB solar panel post to learn why these panels are more efficient AND have a longer usable life than traditional solar panels.
Final Thoughts: Calculating How Much Solar You Need Is Just The Beginning
Figuring out how much solar power your campervan needs is an important first step to building your campervan solar system. But it’s just that, the first step.
If you found this article helpful, check out our DIY solar system build series, where we teach you how to construct your own camper van solar system from scratch.
And if you have any questions or comments, please let us know in the comments section below.