9 Common Solar Installation Mistakes for Van Conversions

Of all the different sections in a camper van electrical system, the most complicated part is the solar system. That’s because this section requires the most calculations, correct product sizing, waterproofing considerations, and more. Unlike other areas of the electrical system, directly copying what you see in a solar diagram might not necessarily be appropriate for your needs.

Therefore, in this post, we discuss the nine most common solar installation mistakes we see in camper van conversions. This is an important post to read BEFORE building your solar system so that you can avoid many of the same errors we’ve seen with other camper vans.

If you’re ready, let’s get to it.

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1. Not Enough Solar Wattage

One of the biggest mistakes van converters make when building a solar system is not installing a large enough solar system to meet their energy demands adequately. In other words, not enough WATTS.

Frequently, we see camper vans with only one or two 100W panels on their roofs. But in many cases, only having 100-200W of solar isn’t enough. This is especially true if you travel outside the summer months or use power-hungry electrical devices like an induction cooktop or water heater.

Solution: That’s why we recommend readers to use our solar calculator. When used with our battery calculator, these services will help you arrive at a solar wattage size suitable for your energy demands.

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2. Wrong Solar Wire Size (AWG)

One of the dangers of strictly copying a solar wiring diagram ‘product for product’ is that it potentially leads you to have undersized wires. This can be a serious fire hazard if a large solar array pushes too much current (Amps) through too thin of a wire.

Solution: That’s why we recommend visitors to read our solar wire size guide. But read this only after you know how many solar watts you will install. Only then can we help recommend 12 AWG, 10 AWG, or even 8 AWG wires for your solar system.

Ancor | 10 AWG Wire (Red)

We love Ancor's 'marine grade' wires for solar installations. The insulation jackets are UV & salt water resistant (good for rooftop installations).

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3. Wrong Solar Charge Controller Size

Just like with the wires, the size of the solar charge controller depends on how many watts your solar array can generate. The larger the wattage, the greater the charge controller’s amp rating needs to be.

For example, Victron Energy sells charge controllers in the following sizes:

  • 10A / 75V
  • 20A / 100V
  • 30A / 100V
  • 50A / 100V

But how do you know which charge controller you need?

Solution: That’s why we recommend that readers read our solar charge controller size guide. Just know how many watts your solar array will have first.

4. Wrong Size Circuit Breakers

Circuit breakers are critical components that protect your solar wires from overheating and catching on fire. But installing just some random breaker isn’t good enough and may not necessarily make your van safer.

T Tocas | 40A Circuit Breaker

This circuit breaker protects the solar wire from overheating and is installed between the solar charge controller and the positive bus bar.

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To calculate the correct circuit breaker amperage, you need to know what size solar wire you will use. Once you know the wire gauge (AWG), you can determine your correct breaker size.

For more information on how to do this, refer to our solar calculator. Once you input all the standard information relevant to your unique build, the calculator will recommend the correct sizes of all the various components you will need to build your solar system.

5. Not Using Marine Grade Solar Wires

For electrical wires inside a camper van, upgrading to high-quality ‘marine grade’ wires isn’t critical. But because some of the solar cables will be outside on the roof and exposed to mother nature’s elements, we recommend going with marine-grade cables.

What are “Marine Grade” wires? These are tinned pure copper wires encased in resilient insulation that resists corrosion when exposed to UV light, salt water, oil, and more. “Marine grade” means these wires meet specific quality standards and can withstand the harsh open ocean environment.

Once you know what size solar wires you need, we recommend using “Ancor” branded wires. We use these wires in our own van and trust their quality.

6. Not Waterproofing the Solar Mounting Brackets

Surprisingly, we still encounter van conversions that do not do enough to waterproof the edges of the solar panel mounting brackets. Whether solar panels are screwed directly onto the roof or attached via a roof rack, there will still be some areas on the roof where water can penetrate through to the inside of the van.

That’s why we recommend thoroughly waterproofing the connection points to the roof. Because once you discover a water leak, there’s likely already too much water damage to fix quickly and easily.

When mounting the solar panels to the vehicle roof, we always recommend a combination of both Butyl Tape and Lap Sealant. This creates a two-layer protection barrier against water entry. For more information, read our solar panel mounting guide.

7. Not Connecting Solar Panels In Parallel

One of the most significant benefits of wiring solar panels in series is its simplicity. However, solar panels wired in parallel are more efficient when partially shaded. And when traveling in a van, the amount of time solar panels are spent partially shaded is longer than you might think.

Two solar panels wired in series and two solar panels wired in parallel
Series vs. parallel solar panel wiring

However, due to the nature of solar wiring and safety, we recommend wiring panels in parallel ONLY IF you have two panels and not more than two. If you have more than two panels, you will need to install in-line fuses, adding additional wiring complexity, cost, and risk.

Therefore, if you originally planned to install three 100W panels, consider getting two 150W panels. Or get two 200W panels instead of four 100W panels. This way, you can still have two solar panels wired in parallel.

For more, read our series vs. parallel solar wiring post.

8. Not Using Rigid Solar Panels

This will probably get us hate mail, but we will say it. We hate flexible solar panels, and we would never consider using them in most van life situations. Compared to rigid solar panels, flexible panels are:

  • More expensive per watt
  • Less efficient at converting sunlight into power
  • More prone to malfunctioning & breaking
  • More prone to overheating

We understand the allure of flexible panels, such as requiring a less invasive installation process and having a thinner profile, which is better for stealth camping. But even after factoring in these benefits, flexible panels still aren’t worth the trouble. In our 4+ years on the road, we’ve met a handful of van lifers who have already had to replace their broken flexible panels or weren’t satisfied with their solar array’s lower power output.

Solution: Get rigid solar panels. Yes, they’re heavier, and yes, they’re more visible. However, having a steady and reliable power production solution is a critical part of any camper van’s build and not something to take risks with.

9. Not Using the Newest & Most Efficient Solar Panels

As of this writing, the newest & most efficient solar panels are assembled with nine bus bars connecting each solar cell. (Legacy panels only have five bus bars linking each cell.) This means electricity can flow more efficiently between the cells with less power loss. Also, the adverse effects of micro-cracks that form in the solar cells over time have a reduced impact because of more bus bars.

Interested to learn more? Read our 9BB solar post.

BougeRV | 200W Solar Panel

We've spoken with BougeRV reps and came away impressed with their customer service. They also make excellent quality, highly efficient '9BB' solar panels. Consider installing a larger 200W panel instead of multiple smaller panels.

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Solar panels assembled with nine bus bars are called 9BB panels, and you can easily find them on Amazon. We recommend the 200W 9BB solar panels from BougeRV. Though this is a Chinese company, they provide high-quality panels and have dedicated English-speaking staff attending all US sales. We know this from experience, and we’re impressed with BougeRV.

Enjoyed reading? For more helpful build content, check out our van conversion guide.

Final Thoughts: Learn From Other’s Mistakes

While building a DIY solar system isn’t rocket science, you do need to be aware of several solar factors before starting the installation process. Staying on top of these issues ensures that you’ll have sufficient power to run all your electronics and that your camper van remains safe from potential fire risks.

If you have any follow-up questions, please comment in the below section.

Happy building!

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