Solar panels are the perfect compliment for camper van conversions. They make you energy independent and allow you to live off-grid. But installing a solar system is a daunting task; there’s lots of different components, wires, and (admittedly) some calculations involved to properly size your system. So it can feel overwhelming when building a camper solar system from scratch.
In this solar guide, we take a step-by-step, methodical approach to get you from ‘zero to solar’ in the quickest, least confusing way possible. And as we mentioned in our comprehensive electrical system guide, you don’t need to be an electrical engineer to build a functioning solar system. (We’re social science and art history majors, and we did just fine, thank you!)
In this post, we include actionable guidance, wiring diagrams, and high-quality product recommendations. Our goal is to not only help you build your van’s solar system but to teach you how all the parts and components come together to charge your camper’s batteries.
If you’re ready for the challenge, we’re here to help. So let’s get to it!
Introduction
The 8 Parts To A Successful Camper Van Solar System
A successful solar ‘PV’ system can be broken down into eight parts. In each section, we provide the necessary information you need to help you plan your system. In summary, the eight parts are:
There are several different types of solar panels on the market today, such as rigid, flexible, and foldable panels. In this section, we go over the pros and cons of each type of panel and give our recommendation based on our experience and from other van lifers we’ve met.
The more power a camper electric system requires, the larger a solar array needs to be to fully recharge a battery bank during the day. In this section, we provide a simple approach to calculating your ideal solar array wattage to ensure you have adequate power to last you throughout the night.
How you connect multiple solar panels together impacts the entire system in several critical ways. In this section, we provide the pros and cons of series and parallel panel wiring and give our recommendation on which connection style we prefer.
The size of your solar charge controller depends on the total wattage of your solar array. In this section, we go over what charge controllers do, why they’re important, and how to calculate the ideal charge controller size for your solar array system.
Your ideal solar wire thickness (AWG) depends on the total wattage of the solar array and whether the array is wired in series or parallel. In this section, we show you how to determine the ideal solar wire size to keep your system safe from overheating and catching fire.
Fuses help keep your solar system safe from overcurrent situations. In this section, we identify the three areas of a solar system that you’ll need to fuse and teach you how to properly size the fuse for each area.
How will you attach the solar panels to your camper’s roof? And will you mount them vertically or horizontally? In this section, we discuss key layout and mounting considerations to make before hoisting the solar panels on top of your vehicle.
Once you have an understanding of the previous seven steps, we provide a step-by-step installation guide to connect your solar panels to the batteries. We include detailed wiring diagrams and key product recommendations so that you can start charging your batteries ASAP.
Chapter 1:
Selecting The Right Solar Panels
In this first chapter, we go over the three different types of solar panels available on the market today and discuss the pros and cons of each type, especially as they pertain to camper vans.
1.1 - Rigid Panels
Rigid solar panels are the most common types of panels and are often found installed on house roofs and in solar power plants. They are also popular among the camper van community because of their sturdy design, which includes a rigid aluminum frame and a top layer of tempered glass to protect the photovoltaic cells. The tempered glass is a critical feature for mobile homes because they protect the cells from scratches and scuffs from low-hanging branches, dust, and sand.
Pros
- High durability
- Longer lifespan (20+ years)
- Cheaper per watt
- More size options
Cons
- Less stealthy
- Invasive installation
Most Popular: Rigid panels are the most popular type of solar panels for camper vans because of their durability and longer lifespan. This is what we use for our van conversion.
1.2 - Flexible Panels
These panels are flexible because they do away with the traditional aluminum frame and tempered glass top layer. Instead, the solar cells are sandwiched in-between plastic and rubber-like material layers that allow the entire panel to flex and bend. This is great when mounting on curved surfaces. Doing away with the rigid frame also means that these panels are thinner and more stealth-friendly.
But the loss of the tempered glass top layer and aluminum frame means that these flexible panels have significantly shorter lifespans compared to rigid panels. It is not uncommon to see permanent scuff marks, sun burns, and a decrease in solar efficiency after just a few months. (Source)
Pros
- Thin profile
- Easy to install
- Mount on curved surfaces
Cons
- Wear & tear easier
- More expensive per watt
Our Opinion: We personally know a camper van traveler who has gone through six flexible solar panels in three years. He’s told us his panels tend to last 6-8 months before needing to be replaced. We would not get flexible panels for our camper van if we can avoid it.
1.3 - Foldable Panels
Foldable solar panels provide the ultimate solution for stealth camping. When not needed, these panels fold away neatly into the van and are unseen by the outside public. And when you need to charge the batteries, take the panel out and point it directly at the sun.
The downsides are you won’t be able to charge your batteries when you are out in a public area and these panels take up valuable storage space inside the van.
Pros
- Great for stealth
Cons
- Most expensive per watt
- Takes up internal storage
- Minimal sun exposure time
- Not great for multiple panels
To learn more about solar panels for campers, read our more thorough van life solar panel comparison.
Our Opinion: Forget about being stealthy. We recommend choosing rigid solar panels to due to the rough nature of van life. Rigid panels last longer, are more durable, and better withstand scruffs from low branches and dirt.
1.4 - High-Efficiency '9BB' Panels
Whichever style of solar panel you do select, we recommend getting the newest, highly efficient ‘9BB’ solar panels. Not only are they more efficient at converting sunlight to usable power, but they also have a smaller area footprint and are more resistant to micro-cracks compared to older technology panels.
To learn more about these specific types of panels, check out our 9BB solar panel post.
Chapter 2:
Calculating Solar Array Size (Watts)
Spending time to calculate the minimum solar array wattage that is suitable for your camper van is a critical step. If the solar array wattage is too small, the panels cannot fully charge your batteries throughout the day. This can lead to an insufficient battery charge during the evening and potentially running out of battery power at night.
We recommend the following 3 steps to calculate the ideal solar array size for your camper.
- Calculate your daily power usage (DPU)
- Determine battery bank size (Amp-hours) from DPU
- Match solar array size to battery bank size
To accomplish steps 1 & 2, check out our post “How To Calculate Your Battery Size”.
Once you have a properly sized battery bank, follow the information and table below to get your ideal solar array wattage.
2.1 - Match Solar Array Size (W) To Battery Bank Size (Ah)
If you have a 12V battery bank, use the below ratios to determine your solar array wattage size.
- If you are using LITHIUM batteries, use a 1:1 ratio of battery bank Ah to solar array watts.
- If you are using AGM batteries, use a 2:1 ratio of battery bank Ah to solar array watts.
Have A 24V System? Use a 1:2 ratio for lithium batteries and a 1:1 ratio for AGM batteries.
Refer to the table below to locate your ideal solar array size (based on 12V battery Ah size AND chemistry). But remember, you should only reference the below table if you followed our battery sizing post first.
Battery Size (Ah) | Solar Array Size (W) (With AGM) | Solar Array Size (With Lithium) |
100Ah | 50W | 100W |
150Ah | 75W | 150W |
200Ah | 100W | 200W |
250Ah | 125W | 250W |
300Ah | 150W | 300W |
350Ah | 175W | 350W |
400Ah | 200W | 400W |
450Ah | 225W | 450W |
500Ah | 250W | 500W |
Our Opinion: The table above only suggests the minimum solar array size that would meet your power needs. If you have extra available space on your roof, feel free to add more panels to your array. We have 300Ah of lithium batteries and have a 360W solar array.
To learn more, read our post on how to calculate your ideal solar array wattage
Building a camper van? Download our free e-Books with intuitive electrical, solar, and plumbing diagrams.
Chapter 3:
Series Vs. Parallel Solar Panel Wiring
Like wiring multiple batteries together, you can also connect multiple solar panels together in either series or parallel. By choosing which way to wire your panels together, you can manipulate the volts and amps that are sent to the solar charge controller from the solar panels. In the below diagram, you can see how the two styles differ when wiring two solar panels together.
What you can initially see is that wiring panels in series is relatively simpler and parallel wiring involves additional components (branch connectors). [Amazon]
There are pros and cons for both wiring styles, which we discuss below, and it will be up to you to decide how you want to connect your panels together.
3.1 - Wiring Solar Panels In Series
Wiring panels in series is the most common approach in camper vans because it is simpler to do and involves less components than wiring in parallel.
To wire panels in series, take the negative line of the first panel and connect to the positive line of the second panel. Then take the negative line of the second panel and connect to the positive line of the third panel. And so on. In the end, you will have one available positive line (from the first panel) and one available negative line (from the last panel) to connect to the solar charge controller.
If you have three solar panels, the final result will look like the series wiring diagram below.
The result of wiring multiple solar panels in series is that the overall solar array voltage (V) is equal to the sum of the output voltage of each individual panel. Essentially, the voltage increases. But the total current (A) stays equal to the current output of a single panel.
- Voltage (V): Adds up
- Current (A): Stays the same
Series Wiring Benefits
For smaller camper van solar setups, the primary benefit for connecting panels in series is that it is a simpler wiring process. There’s less components involved and you don’t have to worry about getting MC4 in-line fuses (we talk more about those later).
Saving Money? Some sites claim you can save money because series wiring allows you to use thinner solar wires since less current (amps) are being produced by the solar array. But the savings is negligible because wire runs are short in a camper van and you would still need to buy thicker wire to connect the charge controller to the batteries. We talk more about solar wiring in chapter 5)
The downside of series wiring is that the total solar array is less efficient when the panels are exposed to partial shading. This is because shading reduces the overall current of the solar array. And arrays wired in series already create less current than parallel arrays. (Source)
Pros
- Simpler to wire
- Less components
- No need for in-line fuses
- Thinner wire (maybe)
Cons
- Less efficient in partial shading
- One faulty panel stops charging
3.2 - Wiring Solar Panels In Parallel
To wire multiple solar panels in parallel, connect all the positive lines together and all the negative lines together using branch connectors.
If you have three solar panels, the final result will look like the parallel wiring diagram below.
The result of wiring multiple solar panels in parallel is that the total current (A) produced by the solar array is equal to the sum of the output current of each individual panel. Essentially, the current increases. But the total voltage (V) stays equal to the voltage output of a single panel.
- Voltage (V): Stays the same
- Current (A): Adds up
Parallel Wiring Benefits
The biggest benefit to wiring solar panels in parallel is that the array is more resistant to the negative effects of partial shade. This is a very real benefit because your camper van will always be parked in partially shaded environments. Whether it’s shade from trees, mountains, buildings, or electrical poles, your solar array will experience lots of shade. So wiring the array in parallel to be more efficient in shaded situations is a smart.
Pros
- More efficient in shade
- One faulty panel does not stop charging
Cons
- More components required
- Solar fuses (maybe)
- Thicker wire (maybe)
3.3 - Series vs. Parallel: Which Solar Panel Wiring Is Best?
Because of their higher efficiency in partial shade, we prefer wiring panels in parallel. However, parallel wiring gets more complex if you have more than two panels. That’s why we recommend the following guidelines.
2 Panels Only --> Wire In Parallel
If you only have two panels, wiring in parallel is the best choice. Not only will these panels preform better in partial shade, but having only 2 panels ensures that you do not need MC4 in-line fuses and that you won’t require needlessly thick wires to connect them to your charge controller.
If you require a larger solar array wattage, consider getting two bigger solar panels instead of three smaller panels.
In Our Van: We installed two 180w solar panels and wired them in parallel
3+ Panels Only --> Wire In Series
For three, or more, solar panels, consider wiring the array in series. Not only will the wiring process be simpler and with less components, but you can use thinner wires since the array is producing fewer amps.
Have A 24V System? You will likely need to wire your panels in series to create voltage high enough to charge your batteries.
To learn more, check out our series vs. parallel solar panel wiring post.
Chapter 4:
Solar Charge Controllers
Solar charge controllers are a vital component to every camper van’s solar system. These controllers take the power produced by the solar array and regulate its voltage so that the power can be accepted by the batteries for proper charging. Without a charge controller, the solar panels would quickly overcharge and destroy the batteries.
To get more details about what a solar charge controller is and why you need one, check out our post.
4.1 - How To Size Your Charge Controller
The first question you’ll need to know is what size charge controller you need.
Charge controllers come in different sizes and are sorted by their amp ratings. For example:
PWM vs. MPPT: These are the two types of controllers on the market today. Unless you are on an extremely tight budget, go for a MPPT controller. They are more expensive, but are more efficient at charging batteries from solar panels.
But a solar charge controller with which amp rating do you need?
The controller size you need is dependent on the total wattage of your solar array. The greater number of watts produced by your solar panels, the more current (A) that will be sent to your batteries for charging. No matter how many watts your solar array can produce, if your charge controller is only rated for 10A, then only 10A will be fed to the batteries. The rest is wasted.
You can reference the below table to find your ideal charge controller size based on the wattage of your solar array.
Have A 24V System? Divide your solar array size by two and use the below table.
Solar Array Size (Watts) | Charge Controller (Amp Rating) | Buy Now |
0-130W | 10A | |
131-200W | 15A | |
201-270W | 20A | |
271W-400W | 30A | |
401W-540W | 40A | |
541W-680W | 50A | |
681W-800W | 60A |
4.2 - Our Recommended Charge Controller
Although pricier, Victron charge controllers are the best option for camper vans. This is because they are one of the only brands that manufacture Bluetooth enabled charge controllers. And with their Victron connect app, you can easily view vital solar statistics, via the Victron app, and keep an eye on your daily solar production.
Through our smartphones, we can also update the controller’s settings, switch the device off for maintenance, and even view a 30-day history of solar harvesting data.
To learn more, check out our Victron solar charge controller review.
Chapter 5:
Solar Panel Wire Size
Getting the correct size wires for your solar system is critical because if the wires are too thin, you run the risk of pushing more current (A) than the wires can handle. This overheats the wires and can eventually be a fire hazard.
And solar systems can produce a lot current for extended periods of time, meaning that even properly sized wires will be quite warm during the day.
In most solar systems, there are two sections of wires that you will need to size independently.
- Solar panels to charge controller
- Charge controller to batteries
We discuss each of these two sections in more detail below.
5.1 - Solar Panels To Charge Controller
To calculate the ideal wire size to connect the solar panels to the charge controller, you will need to know the maximum amps (current) produced by your solar array. Remember:
- Panels wired in series DO NOT add the amps produced by each individual panel.
- Panels wired in parallel DO add the amps produced by each individual panel.
Once you know the solar array’s maximum amps produced, round this number up to the nearest 10. For example:
- If the array can produce 5.5 amps, round up to 10A.
- If the array can produce 13.4 amps, round up to 20A.
In Our Van: Our two 180W panels, wired in parallel, produce a maximum current of 22.4A. Therefore, we round up to get 30A.
Next, take your rounded up number and use the table below to find your ideal wire size (AWG) to connect your solar panels to the charge controller.
Rounded Up Amps | AWG Wire Size | Buy Wire Size |
10 | 12AWG* | |
20 | 12AWG* | |
30 | 10AWG | |
40 | 8AWG | |
55 | 6AWG |
* Though you can use 12AWG wires, we always recommend getting a minimum of 10AWG wires for solar systems.
Marine Grade Wires: For all wires in solar installations, we always recommend 'marine grade' wires. Not only are the wire jackets more resistant to the outside elements (e.g. rain, salt, UV light), but they also have superior insulation. This allows them to handle slightly more amps than conventional, cheaper wires.
5.2 - Charge Controller To Batteries
In this step, you will calculate the wire size required to connect the solar charge controller to the batteries.
Actually...Not Directly To The Batteries: If you've followed our electrical system guide, then you know that we do not wire the charge controller directly to the batteries. We will wire the controller to the bus bars, which are already wired to the batteries.
The wire size you need is dependent on the amp rating of the solar charge controller you selected in Chapter 4. Refer to the table below to locate your ideal wire thickness based on the charge controller amp rating.
Charge Controller (Amp Rating) | Wire Size (AWG) | Buy Wire |
15A | 12AWG* | |
20A | 12AWG* | |
30A | 10AWG | |
40A | 8AWG | |
50A | 6AWG | |
60A | 4AWG |
* Though you can use 12AWG wires, we always recommend getting a minimum of 10AWG wires for solar systems.
5.3 - Summary
In summary, to determine the best size for your solar system, follow the below graphic.
Chapter 6:
Solar Fuses & Breakers
When installing fuses and breakers into a solar system, there are three areas to be aware of.
- MC4 in-line fuses before branch connectors (parallel wiring only)
- Solar DC breaker after solar panels
- DC breaker after charge controller
Refer to the below graphic to locate each of the three areas.
We take a look at each of the three sections below.
6.1 - MC4 In-Line Fuses
Solar fuses [Amazon] only need to be used when three, or more, solar panels are wired in parallel. You do not need a solar fuse if your array is wired in series.
The size of the MC4 solar fuse required is equal to the ‘maximum series fuse rating’ listed on your solar panel.
For Example: This 200W BougeRV panel [Amazon] has a maximum series fuse rating of 15A. So a 15A in-line fuse must be used.
6.2 - Solar DC Breaker After Solar Panels
Not only does this DC breaker [Amazon] protect your wires and connected devices from unforseen surges, but you can also flip the breaker and disconnect the solar system to conduct maintenance on the system.
To select the ideal breaker for your system, identify the total short circuit current (Isc) produced by the array, then multiply by 1.25 (NEC safety factor) and multiply by 1.25 again (for continuous current). Then round up the result to the next available breaker size.
For Example: Two 200W Newpowa panels [Amazon] wired in parallel has an Isc of 22.94A (11.47 x 2). Then, 22.94A * 1.25 * 1.25 = 35.8A. Rounding up means a 40A breaker is appropriate to use.
6.3 - DC Breaker After Charge Controller
The size of the DC breaker [Amazon] after the charge controller is related to the amp-rating of the charge controller itself.
To calculate the breaker size, take the amp rating of the controller and multiply by 1.25. Then round up the result to the next breaker size.
For Example: If you have a 30A charger controller, multiply 30A * 1.25 to get 37.5A. Rounding up means a 40A breaker is appropriate to use.
6.4 - Fuse Summary
By installing the three different fuses discuss above, your wiring system may look similar to the diagram below.
Check out our solar fuse guidelines post to learn more.
Building a camper van? Download our free e-Books with intuitive electrical, solar, and plumbing diagrams.
Chapter 7:
Mounting Solar Panels To Camper Roof
Before installing any solar panels on your camper’s roof, it’s important to think about the following two issues.
- Solar panel layout – How will you arrange the solar panels on your roof? Horizontally or vertically?
- Direct mount vs. roof rack – Will you install the panels directly to the camper’s roof? Or install the panels onto a roof rack instead?
We discuss each of these two sections below.
7.1 - Solar Panel Layout Planning
There are two ways to orient your solar panels on the roof; horizontally (left to right) and vertically (back to front). The two main factors determining your panel’s orientation will be the dimensions of your vehicle’s roof and the individual dimensions of each panel.
Refer to the diagram below for two solar panel layout examples.
Creating an accurate solar panel layout plan that is to scale isn’t difficult. But you will need the exact dimensions of your camper van’s roof and the dimensions of the solar panels. Once you have that, you can use any paid or free drawing software to see how the solar panels look on the roof. For more information on how to do this, we recommend reading the following posts.
7.2 - Direct Mount vs. Roof Racks
The second important question to answer is ‘how’ you will attach the solar panels to your camper van’s roof. The most common choices are to either mount the panels directly to the vehicle’s roof or by attaching the panels to a roof rack.
Direct Mount
Involves screwing the solar panels directly onto the roof. This method gives the panels the lowest profile and attracts the least attention, which is beneficial for stealth campers. But the downsides are that you may have potential water leaks in the future and that removing the panels for maintenance is a hassle.
Roof Rack
If done right, roof racks can be installed without drilling any new holes in your camper’s roof. Then simply attach the solar panels to the roof rack. No potential for roof leaks and you can easily remove the panels when needed. The downsides are that the panels will be elevated slightly more off the roof, bringing more public awareness. Not all roof racks are the same, and these ones from Flatline Van Co look pretty slick!
Our Opinion: We installed solar panels directly to our van’s roof. They’ve worked great, look streamlined, and we haven’t had any leaks (yet). But we if could do our build again, we’d spend the money on a low profile roof rack instead.
We used a combination of 3M VHB tape and Butyl tape to ensure that our solar panel installation is not only secure but also waterproof. To learn more, check out our solar panel mounting post.
Chapter 8:
Solar Panel Wiring Installation (Step-by-Step)
In this last chapter, we show you how to wire a solar panel system in a camper van. We also discuss all the different devices, components, and wires you will need to complete the installation. When completed, your solar system should look similar to the diagram below.
By the way…for more solar wiring variations, download our custom solar diagrams eBook. It’s completely free. And no pesky email sign-ups.
Solar Panels
With so many types and sizes of solar panels on the market, it can be paralyzing to know which panels to choose.
Whichever you do select, make sure you’re getting the highest efficiency solar panels with ‘9BB’ technology, like these panels from BougeRV [Amazon].
Learn more: What are 9BB solar panels?
Stranded Copper Wire (Red & Black)
We discussed how to select the best size solar wire in Chapter 5.
Whichever size wires you need, make sure they’re ‘marine grade’. That’s because a portion of these wires will be located outside, on your camper’s roof. Marine grade wires offer the best protection against the outside elements.
10 AWG wire is what most camper vans will need, but check out our solar wire calculator post to help you choose the best wires for your solar system.
MC4 Connectors
MC4 connectors are the standardized connection type for solar systems.
Although solar panels come with two pre-attached MC4 connectors, you will need at least one additional pair to complete your system.
MC4 Branch Connectors
If you will be connecting multiple solar panels together in parallel, you will need branch connectors to complete the wiring process.
- For two solar panels, use these 2-1 connectors.
- For three solar panels, use these 3-1 connectors
MC4 In-Line Fuse
If you are wiring 3 (or more) solar panels in parallel, you will need to install these MC4 in-line fuses onto the branch connectors. These fuses protect each individual solar panel from short circuit situations and prevent potential fires.
The size of the in-line fuse you need is depend on the ‘maximum series fuse rating’ of your solar panels. Read our solar fuse guidelines post for more information.
Solar Entry Gland
This entry gland attaches to the roof of your van and protects the solar wires as they enter the vehicle from the outside.
Silicone sealant comes included with this product.
Solar DC Breaker
Not only does a DC breaker [Amazon] protect your wires and connected devices from unforseen surges, but you can also flip the breaker to disconnect your solar system so that you can conduct maintenance on the system.
We teach you how to size the correct solar DC breaker for your system in Chapter 6.
Solar Charge Controllers
Charge controllers regulate the voltage from the solar panels to the batteries and is a critical device for any solar system. We show you how to calculate the ideal charge controller size for your solar system in Chapter 4.
Check out our additional charge controller resources to learn more:
Circuit Breaker
The circuit breaker protects the solar wire from overheating and all downstream electrical components from any unforeseen surges in power.
We show you how to size this circuit breaker in Chapter 6.
Connect your solar wire to the circuit breaker with appropriately sized ring connectors. If using 10 AWG solar wire, these M6 ring connectors [Amazon] will work.
Ring Connectors (To Bus Bars)
Use ring connectors to connect the solar wire to the bus bars. If you use our recommended bus bars [Amazon], get size M10 ring connectors.
You must also size your solar wires before selecting your ring connectors. If, like us, you are using 10 AWG solar wires, these exact M10 ring connectors [Amazon] will be what you need.
Miscellaneous
FAQ
Surprisingly, you do not need a huge garage full of random tools to build your own camper solar system. You should be able to complete most of the installation process with the below 3 tools:
- Wire crimper [Amazon]
- MC4 assembly tool [Amazon]
- Electrical drill [Amazon]
If you value being energy-independent and getting off-grid, solar panels are absolutely worth the investment. If you are on a tight budget, we provide a solar solution that costs less than $450.
If you follow our solar sizing guide, we don't think tilt panels are worth the money and trouble. Our solar panels do not tilt and we are getting PLENTY of solar power into our batteries each day.
Conclusion
We hope this camper van solar installation guide was useful for your van conversion project. Although building a solar system can appear daunting, we’re confident that you can install your own DIY system by going slow and doing your homework ahead of time.
If you have any questions, please don’t hesitate to ask by sending us an email through the contact page.
Lastly, be sure to check out our eBooks with useful wiring diagrams. They are a valuable resource and are all completely free to use.
Happy building!
Go Back: DIY Camper Van Conversion Guide
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