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The Complete Guide to Campervan Solar Systems

Did you know that the amount of sunlight that strikes the earth's surface in an hour and a half is enough to handle the entire world's energy consumption for a full year! Solar power for van conversions is totally essential. In the Roaming Home 2023 study we found that 78% of people install a campervan solar system.

In this we will learn how solar panels work and how to choose the right solar panel kit. We will also look at campervan solar panel installation.

I’m Shane, a van conversion professional dedicated to helping people transform ordinary vans into homes on wheels. I've authored Roaming Home, and teach The Van Conversion Course, guiding many people through their van builds. I also write The Van Conversion Newsletter, where I share practical tips and insights. After completing two van builds and living on the road full-time since 2020, I’m excited to share my expertise with you.

Now let's jump in and have a look at campervan solar setups!

Index

 

Note: Before we hop in, you will definitely want to grab yourself a wiring diagram which you can get for free by signing up to The Van Conversion Newsletter


This post contains affiliate links, which means that if you click a product link and buy anything from the merchant (Amazon, eBay, etc.) we will receive a commission fee. The price you pay remains the same, affiliate link or not. By using these links, you are helping me to continue writing free educational content! To understand our policies on content, affiliate commissions, and liability, please review our Terms of Use.

 

Supplies list 🛒

Bluetooth monitor

​Bluetooth monitor

Monitor your Renogy solar charge controller with your phone


Adhesive cable clips

Adhesive cable clips

Securing the solar cables on the roof


10awg solar panel cable

10AWG solar cable

Connecting solar panels & solar charge controller


Solar cable entry

Solar cable entry

Passing solar cables through the roof


40a inline breaker

40a inline breaker

Protect the Solar Charge Controller from surge


40a inline breaker

50a inline breaker

Protect the rest of the electrical system from surge

Isolator switch

​Isolator switch

Leisure battery kill switch


200a ANL fuse

​200a ANL fuse

Protects the leisure battery in case of surge

Leisure battery terminal connector

Leisure battery terminal connector

For connecting cable to your leisure battery


250a bus bar

​2X 300a heavy duty bus bars

Common connection point for positive and negative cables

Leisure battery

12v fuse box

​12v fuse box

To protect all your 12v appliances

Heavy duty lugs

​Heavy duty lugs

For connecting cables to the bus bars

Victron battery montior

​Victron battery monitor

For monitoring the levels of your batteries


The anatomy of a campervan solar system

To install a campervan solar system, you need three components:

  1. Solar panel(s)

  2. A solar charge controller

  3. Leisure batteries

How do solar panels work?

Photovoltaic panels (PV), also known as solar panels convert energy from the sun (photons) into electricity which you can use to power your campervan.

When the sun shines onto a panel, the energy is absorbed by the PV cells. The photons knock electrons free from atoms, generating a flow of electricity.

The solar cells form an electrical circuit in the panel, thus allowing the flow of electrons through the circuit, creating electricity.

What size solar panels for a campervan?

In the Roaming Home 2023 study, we found that most people install a 300W campervan solar setup, followed closely by a 400W solar system. Though the results were quite distributed.

What size solar should I install on my campervan?

When sizing solar panels for off-grid living, it's essential to balance your energy consumption with the solar panel output and battery storage. Start by calculating your daily energy usage using an energy consumption calculator. Then, ensure your solar panels can generate enough energy to cover that demand, even on less sunny days.


Steps to Size Solar Panels

  1. Estimate Daily Load: Add up the watt-hours (Wh) of all appliances and devices you'll use daily.

  2. Factor in Solar Efficiency: Account for system losses (inverters, wiring), and local solar irradiance data (hours of sunlight per day).

  3. Choose Appropriate Battery Storage: Ensure you have enough storage to handle several cloudy days.


For full-time off-grid living, a 300-400W solar setup is common, but higher capacities may be needed depending on your consumption and location.


To help you figure out what size solar panels you will require for your van conversion, we have built a solar panel calculator. First you will need to figure out your expected daily electrical load which you can calculate using our Energy consumption calculator.

solar panel calculator

How Much Energy Can Solar Panels Generate in Different Conditions?

Solar panels perform differently depending on a variety of factors, including geographical location, time of year, weather, and tilt angle. Understanding how these conditions impact solar energy production can help you optimize your campervan's solar system and set realistic expectations for how much power you'll generate.


Key Factors Affecting Solar Output

  1. Geographical Location

    • Solar energy is more abundant in some parts of the world than others due to varying solar irradiance (the amount of sunlight reaching the earth). For example, places closer to the equator receive more consistent sunlight throughout the year compared to higher latitudes.

    • Example: In southern Spain, solar panels can produce up to 40% more energy annually than in northern Germany, due to the difference in sunlight hours and intensity.

  2. Time of Year

    • Solar panel output fluctuates significantly with the seasons. In the summer, longer daylight hours and a higher sun angle increase energy production. In the winter, shorter days and lower sun angles result in reduced energy output.

    • Example: A 300W solar panel system in London might generate around 1.2 kWh/day in summer but only 0.3 kWh/day in winter.

  3. Weather Conditions

    • Cloud cover: On cloudy days, solar panel output can drop by 50-90% depending on cloud density.

    • Rain: While rainy conditions reduce sunlight, rain can actually improve solar panel efficiency by cleaning off dirt and debris that could otherwise block sunlight.

    • Temperature: Contrary to popular belief, solar panels work more efficiently in cooler temperatures. While panels are most effective under direct sunlight, cooler temperatures can increase their efficiency due to lower thermal losses. Heat increases the electrical resistance in solar cells, reducing their efficiency. Panels operating in cooler climates can sometimes outperform those in hot, sunny regions despite receiving less sunlight. For every 1°C drop below 25°C, solar panel efficiency can improve by 0.3-0.5%, depending on the panel type.

  4. Solar Panel Tilt Angle and Orientation

    • Solar panels perform best when they are angled directly towards the sun. The optimal tilt angle changes depending on your latitude and the season. Panels mounted flat on your van roof will produce less energy than those with an adjustable tilt, especially in winter.

    • Tip: Use a tilting mount to adjust the panel angle based on your location. If you're in the northern hemisphere, tilt panels at an angle equal to your latitude for optimal year-round performance.


Real-World Energy Production Examples

  • 300W Solar Panel System in California (Good Sunlight):This system can produce approximately 1.2-1.5 kWh/day on average in summer and 0.6-0.8 kWh/day in winter.

  • 300W Solar Panel System in Scotland (Less Sunlight):In summer, it might produce 0.8-1.0 kWh/day, while in winter, output could drop to 0.2-0.4 kWh/day due to the lower sun angle and shorter days.


Tools to Calculate Solar Potential

To estimate the energy your solar panels will generate given your specific conditions, use a tool like the Global Solar Atlas. These tools allow you to input your location and system specifications to get a detailed estimate of solar energy production under different conditions.


Optimal solar panel angle

The ideal angle for a solar panel installation is roughly equal to the latitude you are currently residing (not accounting for seasons). If your panels are perpendicular to the sun, and pointing directly at it, you will have a big increase in efficiency.

Renogy sell excellent solar panel tilting kits. Or if you felt up to the task, you could build your own instead!

4waysolar.com
Optimal solar panel tilt

For this reason, it is quite common (and extremely useful) to install a tilting solar panel rack on a campervan.

Hench tilting solar panels by @vandmvanlife
Hench tilting solar panels by @vandmvanlife

Regulatory Guidelines for Solar Installations in Campervans (BS 7671 & NEC)

When installing a solar system in your campervan, it's critical to follow both the BS 7671: IET Wiring Regulations (UK) and the NEC 690: Solar Photovoltaic (PV) Systems (USA) for safe and compliant installations. Below are the specific articles from each standard that are relevant to your campervan solar setup.


BS 7671 - UK Wiring Regulations

Article 712.411.3.2 – Earthing and Grounding: All exposed metal parts of the solar PV system, including the solar panel frames and the charge controller, must be earthed to prevent electrical hazards. Ensure grounding through the van chassis for safe operation.


Article 712.434 – Overcurrent Protection: All circuits connected to solar panels must include overcurrent protection (MCBs or fuses). For example, a 40A DC MCB should be installed between the solar panels and the charge controller to protect against faults or short circuits.


Article 712.521.2 – Cable Management: Solar cables should be protected from mechanical damage, UV radiation, and temperature changes. Use appropriate cable conduits or clips to secure cables to the van roof and route them safely inside the vehicle.


National Electrical Code (NEC) - United States

Article 690.13 – Disconnect Requirements: A solar disconnect switch must be installed between the solar panels and the charge controller, allowing for easy isolation of the solar system during maintenance or emergencies.


Article 690.31 – Wiring Methods: All PV wiring must be protected from physical damage and must be UV-rated if exposed to sunlight. Additionally, PV cables should be secured every 4.5 feet to prevent movement and wear.


Article 690.35 – Ungrounded PV Systems: If you're installing an ungrounded solar system (common in modern setups), make sure to use PV modules that meet the latest IEC 61730 standards and include appropriate overcurrent protection.


Article 690.8 – Circuit Sizing and Current: This article emphasizes proper sizing of conductors based on the maximum output current of the solar panels. For instance, if your panels can produce 30A, you'll need 10 AWG wire to handle the current safely.


General Guidelines for Solar Installations (Cross-regulation)

Overcurrent Protection: Both BS 7671 (712.434) and NEC (690.8) mandate overcurrent protection. An appropriately sized DC MCB (typically 40A) should be installed between the panels and charge controller, as well as between the charge controller and leisure battery.


Grounding: BS 7671 (712.411) and NEC (690.43) require proper grounding for all solar PV systems. For campervans, the solar panels and electrical components should be grounded to the chassis to prevent electrical faults and ensure safety.


Cable Size: Ensure correct cable sizing to handle the current produced by the solar panels, as specified by NEC (690.8) and BS 7671 (712.521). For example, if your solar array produces 40A, you may need 10 mm² or 10 AWG cables to ensure minimal voltage drop and prevent overheating.


Voltage Drop: Both standards stress minimizing voltage drop, especially in solar systems with long cable runs. Use thicker cables and keep the length between the panels, charge controller, and batteries as short as possible to maximize efficiency.


Double Pole Disconnect: NEC 690.13 (E) and BS 7671 (712.411) specify that both the positive and negative cables should be disconnected in case of isolation, making double-pole MCBs the recommended choice.


By adhering to these guidelines, your campervan solar system will be safe, efficient, and compliant with both UK and US standards, ensuring optimal performance and durability.



Monocrystalline vs Polycrystalline vs. Thin film solar panels


There are three types of solar panels you can use for your campervan:

  • Monocrystalline

  • Polycrystalline

  • Thin film

Monocrystalline and polycrystalline are both rigid, while thin film is flexible.

Thin film vs monocrystalline vs polycrystalline solar panels for van conversions

Monocrystalline solar panels

Pros: Most efficient campervan solar panel, long life, long warranty (20 years on average)

Cons: Heavier, bulkier, don't bend, less rugged

van conversion electrics course

Polycrystalline solar panels

Pros: long life, long warranty (20 years on average), cheaper than monocrystalline

Cons: Heavier, bulkier, don't bend, less rugged, not as efficient as monocrystalline

Flexible solar panels (thin film)

Pros: Very light, super-slim (stealthy), bendy, more rugged

Cons: Less efficient, shorter warranty (5 years on average)

Campervan Solar Panel Kit

The most popular campervan solar panel kit comes from Renogy. They supply either 2X 100w monocrystalline campervan solar panel kit OR a 4X 100w monocrystalline campervan solar panel kit . Each campervan solar setup comes with an MPPT solar charge controller.

Campervan Solar Panel Kit

Portable Solar Panels

Portable solar panels are a versatile option for vanlifers, offering flexibility in power generation. Unlike fixed roof-mounted panels, portable panels can be set up wherever sunlight is optimal, making them ideal for shaded parking spots or for users who want to move their panels throughout the day to follow the sun.


Advantages of Portable Solar Panels

  1. Positioning Flexibility: You can position portable panels to maximize sun exposure, even if your van is parked in the shade.

  2. Easy Setup and Scalability: Many systems are plug-and-play, and you can easily add additional panels if your power needs increase. They’re available in various wattages, typically ranging from 100W to 200W per panel, with higher-end systems reaching up to 300W.

  3. Efficiency Gains: Portable panels can often be manually adjusted to the optimal tilt angle (equal to your latitude) for maximum efficiency, unlike fixed panels that might be stuck at a suboptimal flat or semi-flat position. This results in a 10-25% efficiency improvement depending on conditions.

  4. Backup Power Source: Portable panels serve as excellent backups or supplements to roof-mounted systems, providing additional power during high-demand situations or when roof-mounted panels underperform due to shading.


Disadvantages of Portable Solar Panels

  • Setup Time: Portable panels require manual setup and takedown each time you move locations, which can be inconvenient for users looking for simplicity.

  • Storage Space: Since the panels aren’t fixed, you’ll need to find a safe, dry storage space inside the van when they’re not in use.

  • Security: Unlike roof-mounted panels, portable panels can be more susceptible to theft if left unattended while in use.


Campervan solar panel wiring diagram

You can wire up campervan solar panels either in series or in parallel.

Wiring solar panels in series

In order to wire solar panels in series, we daisy chain them together. The positive from one panel runs into the negative of the next panel. We then run the last remaining positive and negative cables (on each end of the system) down to our solar charge controller.

When we wire campervan solar panels in series, the amperage (current) remains the same, but both the voltage and wattage increase. For example, Each solar panel in the diagram below is a Renogy 100W monocrystalline panel. Each panel has a max voltage of 18.6V, giving us a max of 5.38A per panel. When we wire the four campervan solar panels in series, the voltage increases to 74.4V and the wattage increases to 400W.

How to wire solar panels in series

In a nutshell, when we wire campervan solar panels (or any device) in series, they act as a single unit - like one huge solar panel.

Advantages Of wiring solar panels in series:

  • Can use smaller wire size due to lower current

  • Wiring is more simple, requiring less connectors and equipment

  • Normally output higher power

  • Distance is less important to efficiency

Wiring solar panels in parallel

In order to wire solar panels in parallel, we connect all the positives together and all the negatives together. The combined positive and negative cables run down to our solar charge controller.

When we wire campervan solar panels in parallel, the voltage remains the same, but both the amperage and wattage increase. For example, Each solar panel in the diagram below is a Renogy 100W monocrystalline panel. Each panel has a max voltage of 18.6V, giving us a max of 5.38A per panel. When we wire the four solar panels in series, the voltage remains at 18.6V but amperage increases to 21.52A and the wattage increases to 400W.

How to wire solar panels in parallel

The BIG advantage to wiring in parallel is that the panels are not inter-reliant on each other; if one of the solar panels is dirty or in the shade or broken, the others are not affected. In contrast, when wiring in series, if you are parked partially under the shade, your campervan solar system efficiency will be greatly reduced.

This is an important advantage, as in my experience I have found it very common that I am parked partially in the shade.

However this advantage comes with more technical wiring and the necessity to use thicker cabling.

To connect parallel solar panels together, we have two options: MC4 connectors or a combiner box.

MC4 connectors

One method of connecting multiple panels on your roof is to use a device called an MC4 connector. An MC4 connector routes many wires into one. If you have 2 panels, you will need a 2-to-1 MC4 connector, or if you have 4 panels, you will need a 4-to-1 MC4 connector.


How to wire MC4 connectors

Combiner box

Another way to marry the solar cables together is to use a solar combiner box, a consumer unit specifically for solar panels. This both combines and fuses (breaks) the solar cables.

A combiner box is generally only needed in larger systems with a lot of solar panels. Van conversions can generally do with just a set of MC4 connectors.

How to wire a solar combiner box

Effect of Shading on Solar Panels

Shading can have a significant impact on the performance of your solar panels. Even a small amount of shading—whether from trees, buildings, or even dirt—can dramatically reduce the amount of energy your solar panels produce. Understanding how shading affects different solar panel configurations is crucial for optimizing the performance of your campervan’s solar system.


How Shading Impacts Solar Panel Output

When part of a solar panel is shaded, the energy output of the entire panel decreases because the shaded cells produce less electricity. In some cases, shading a small portion of a panel can reduce its output by 25-40%. This is particularly true when solar panels are wired in series, where the performance of the entire string of panels is reduced by the weakest link.


Example: If you have four panels wired in series and one is partially shaded, the total power output of all four panels could drop dramatically, as all the panels are forced to operate at the reduced output of the shaded panel.


Shading Impact in Series vs. Parallel Wiring

Series Wiring: When solar panels are wired in series, they form a chain where the same current flows through each panel. If one panel is shaded, it reduces the current, affecting the output of the entire string. This means that even if only one panel is partially shaded, the energy production of the entire array can plummet.


Parallel Wiring: In a parallel setup, each panel operates independently, so if one panel is shaded, the others continue to generate power at their full capacity. This wiring method is more resistant to shading issues but requires thicker cables and more components to handle the increased current.

The Importance of Panel Placement

Given how shading impacts solar panel performance, proper placement of your panels is essential. Consider the following when installing panels on your campervan:

  • Avoid shaded areas: Even partial shading can severely limit energy production. Plan your parking or mounting locations to avoid trees, buildings, or roof racks that may cast shadows.

  • Clean regularly: Dirt, bird droppings, and debris can also block sunlight, acting like shade. Regular cleaning can help maintain maximum output.


How to Minimize Shading Issues

  1. Use Bypass Diodes: Bypass diodes are installed in many solar panels to minimize the impact of shading. These diodes reroute electricity around shaded cells, preventing the entire panel's performance from being affected. Look for panels with built-in bypass diodes for better performance in partially shaded environments.

  2. Opt for Parallel Wiring: While parallel wiring requires thicker cables and more components, it can significantly reduce the impact of shading, making your system more efficient in less-than-perfect conditions.

  3. Install Adjustable Mounts: Use tilting or adjustable mounts to reposition your panels and avoid shade. Adjusting the angle of your panels can also help optimize solar energy collection, particularly in areas where shadows move throughout the day.


Real-World Example of Shading Impact

Research by the National Renewable Energy Laboratory (NREL) shows that even light shading—such as a shadow from a nearby tree branch—can reduce panel output by 20-30%, depending on the size of the shadow and the wiring configuration of the solar system​. In urban or shaded environments, parallel wiring or flexible portable panels can help mitigate these losses.


Solar panel fusing

It is essential that we add a circuit breaker between the solar panels and the solar charge controller. Specifically, we must install a double pole DC MCB; 32A is generally used, though you should do your own sizing. The MCB should have a minimum rating of 250V. It can be installed on a DIN rail inside a small garage consumer unit. A solar-specific MCB like the one shown below can easily be purchased online.

32A DC double pole MCB inside a mini consumer unit
32A DC double pole MCB inside a mini consumer unit

We must use an MCB for two reasons:

  1. Inline breakers (like those from BlueSea or Eaton-Bussmann) are generally rated up to 48V max. This may cause problems if you are wiring your panels in series, where the voltage increases as panels are added.

  2. Inline breakers do not satisfy the “Must disconnect both the positive and negative wire” requirement set by NEC 2020 Article 690.13 section (E).


Solar charge controllers

A solar charge controller is a device which keeps our leisure batteries from overcharging by regulating the voltage and current coming from the campervan solar panels. It converts the powerful electricity from our solar panels into electricity our leisure batteries can use.

A solar charge controller ensures that the voltage and amperage matches the expecting charge stage of the battery. It is paramount that it does its job correctly. For example, if we had a campervan solar panel installation with four panels wired in series (74.4V) wired directly to our leisure batteries, the sulphuric acid would begin to boil and we could be in for a very, very dangerous time indeed.


What is the difference between a PWM and a MPPT solar charge controller?

There are two types of solar charge controllers: MPPTs (Maximum Power Point Tracking) and PWMs (Pulse Width Modulation).

PWMs

A PWM is a relatively simple device that is essentially a smart switch. It pulsates on and off, recognising when it needs to send power to the batteries (per the charge profile). It is about half the price of an MPPT, but about 30% less efficient per day (big difference!).

PWMs draw current from the campervan solar system just above the voltage of your leisure batteries.

MPPT

A MPPT is a solar charge controller which digitally tracks the charge profile of the leisure batteries in order to be as precise as possible with its energy delivery. They are a lot more efficient than PWMs

MPPTs are a little more expensive, but accelerate solar charging of the battery up to 30% per day. MPPTs are slowly but surely taking over from PWMs entirely.

MPPTs draw current from the campervan solar panels at the max voltage possible.


renogy

What size solar charge controller do you need?

Sizing your MPPT correctly turns out to require some fairly complicated maths. To simplify things we have built an MPPT sizing calculator which figures out exactly what MPPT you will need.

mppt sizing calculator

To simplify the math and give you a simplified overview of how to size an MPPT; let's say we have four 100W solar panels wired in series flowing to our 12V batteries.

We must figure out how many amps at 12V our solar panel set will actually produce. We can see that our solar charge controller must be able to handle 400W ÷ 12V = 33.7A. So we should buy a solar charge controller that is slightly bigger, for example a 40A solar charge controller.

Campervan solar panel installation (Step-by-step)

In this step by step guide, I will be showing you how to install solar panels on the roof of your campervan. First we will look at how to install flexible (thin film) solar panels, then we will look at how to install rigid mono/polycrystalline solar panels. I have flexible solar panels on my campervan because they are more discreet than solid.


Note: Before we hop in, go grab yourself a wiring diagram which you can get for free by signing up to The Van Conversion Newsletter (the wiring for the campervan solar system is included in the diagram 🙂 - wiring diagram gets sent out to you straight away).


How to install flexible solar panels on a campervan



Step 1: Clean the roof

Not much to say here... Get up on your van roof with some warm soapy water and get to work!

Step 2: Remove rust from the top of the campervan

Whether or not you're installing solar panels on your campervan, removing rust is always a good thing! If you need a refresher on how to do this, read this guide on how to remove from from a van.

Remove rust from roof of campervan

Step 3: Stick strips of 3M VHB (Very High Bondage) tape on the van

Place strips of the double-sided 3M VHB tape on the roof of your van. This stuff alone will stick the campervan solar panels down for life.

Strips of VHB tape to connect solar panels to roof

Step 4: Stick the flexible solar panels onto the roof of the campervan

Carefully place the flexible solar panels on top of the 3M VHB strips and gently press them down.

Solar panel temperature: Cooler solar panels are more efficient. Flexible solar panels can get quite hot if there is no air gap underneath them. Luckily on the Ford Transit, there are ridges that run down the length of the van, providing an air gap of about an inch, through which air can flow. If your van does not have ridges, you can still install flexible panels, though they might not be as efficient. Alternatively, you could raise the panels up using metal risers.

Air tightness: Some people use high bondage glue (like sikaflex) instead of VHB tape. This is fine too. However, if you are using glue, make sure you pour it in strips, just like the VHB tape. DO NOT make an airtight seal with the glue - water can get trapped in there, expand, and do damage to the panels. It will also reduce the efficiency of the panels due to higher heat.

Stick solar panels to roof of van

Some people choose to secure the panels to their van even more by using well nuts in each of the four corners of each solar panel. A well nut is like a rivnut / plusnut; it is used to fasten something to a surface and to seal the bolt hole. As the bolt is screwed in, the well nut expands on the inside, thus locking it in place.

I can tell you that after years of living in my van full-time, using only VHB tape, I have never had a single problem with my solar panels coming loose. In my opinion, nuts are not really needed.

well nut for attaching solar panel to van conversion

How to secure solar panels with well nuts:

  1. Drill a hole through the van to match the corner of the solar panel. The hole size should match the size of the well nut (M8 - M10 preferable for a solar panel)

  2. Place the well nut through the panel and into the hole

  3. Screw an appropriate bolt into the well nut and the well nut will gradually expand and seal the hole.

  4. For extra waterproofing, I would highly recommend using some sealant on top of the well nut to be super-duper sure you won't get a leak.

Step 5: Stick down loose wiring on the roof using adhesive cable clips

Next, we want to get all that messy wiring out of the way and make it look nice! Use cable ties to bunch everything together and stick it to the roof with adhesive cable clips. I would advise using the 3M VHB tape to stick the cables down.

Step 6: Wire up the campervan solar panels and bring the cables inside the van

Wire up the campervan solar panels either in series or parallel, as discussed before. Most people use 10 mm² solar cable for this job.

how to wire flexible solar panels

Then bring the positive and negative wires inside the van. The wires enter into the van through a solar cable entry gland. You can learn how to install the solar cable entry gland in this guide.

Solar cable entry gland

Step 7: Add an MCB to the solar wiring before the solar charge controller

Add an appropriately sized DC double-pole MCB to the positive wire running to your solar charge controller. I used a 40A inline breaker (because I can expect 33.3A maximum to be delivered). We want to place the breaker as close to the panels as we can get it (to protect as much of the wire as we can).

solar breaker installation

SAFETY NOTE: DO NOT HOOK THE SOLAR CHARGE CONTROLLER TO THE SOLAR PANELS UNTIL THE LEISURE BATTERIES ARE CONNECTED.

It can fry your solar charge controller. Beware.

Step 8: Connect the solar charge controller to your bus bars

The next part of the solar panel installation is to wire the solar charge controller to your positive and negative bus bars. The bus bars run down to your batteries. We add a 50A inline breaker (Bluesea or Bussmann only) to the positive line running to the bus bars. I used two 300A heavy duty bus bars and 10 mm² cable.

Heavy duty bus bars
Heavy duty bus bars

Note: All cable that runs into the solar charge controller should be connected with ferrules to ensure a solid and safe connection.

Bus bar to mppt

The wire from the solar charge controller is connected to the bus bar using a large lug.

Large lug connector
Large lug connector

Step 9: Connect your 12V fuse box to your solar charge controller

Last step! Connect your 12V fuse box to your solar charge controller.

12V fuse box
12V fuse box

This will send power to all your 12V appliances (fan, heater, lights, etc.). I used 10 mm² cable in my van build and added a 40A breaker onto the positive wire (as close as possible to the solar charge controller).

MPPT to fuse box

Connecting the fuse box to your MPPT is technically optional. You could run the fuse box directly from the bus bars. However there are two benefits of running the fuse box from the MPPT:

  • You can power your appliances directly from the solar panels when the sun is out (rather than running through your leisure batteries)

  • You get a bunch of cool monitoring capabilities on the MPPT

Most people will also wire up a 12V switch board after the fuse box before running the wiring out to the individual appliances. This allows you to turn individual appliances on and off. In my opinion it’s a must! We will look at how to wire one in a later chapter.

12V switch panel
12V switch panel

Step 10: Ground it

Many solar charge controllers do not need independent grounding - it is enough that the common negative bus bar in the system is grounded. It is best to check the manufacturer’s guidelines for more information on your model. For instance, only the 20A Victron MPPT needs grounding.

How to mount rigid campervan solar panels

First go grab yourself a campervan solar panel kit, like this awesome 400w kit from Renogy.

  1. First attach metal brackets to the campervan solar panels. The Renogy campervan solar panel kit comes with a Z-bracket mounting system, which allows an Inch of room underneath for airflow to increase the efficiency of the panels.

  2. Bring the bracket-mounted solar panels up onto the roof of your van and mark with a pen where you need to drill into the van.

  3. Drill into the spots you have marked on the roof with a drill bit appropriate to the size of your bolt.

  4. Bolt the campervan solar panels into the roof (place the bolt into the hole from above, and screw the nut on from inside the van).

Note: To get a waterproof seal, I would advise applying a good amount of sealant around the hole you have drilled before tightening down the bolt. Alternatively, you could add a small piece of mastic / butyl tape over the hole. Some people choose to use Loctite Marine Adhesive instead. All three of these options will work.


Here is a great video on how to install rigid solar panels on a campervan.


Solar Panel Lifespan and Maintenance

Solar panels are highly durable, with most monocrystalline and polycrystalline panels lasting 25-30 years. Their performance gradually decreases over time, typically losing around 0.5-1% efficiency per year. This degradation rate is factored into most warranties, which often guarantee 80-85% output after 25 years.

Year

Efficiency (%)

0

100

5

95

10

90

20

80

25

75

*Assuming 1% loss in efficiency per year


Factors Affecting Solar Panel Lifespan

  • Weather: Extreme weather, such as hail or high winds, can cause physical damage, though high-quality panels are designed to withstand these conditions.

  • Temperature: Excessive heat can accelerate wear, particularly in thin-film panels, which are more temperature-sensitive than rigid panels.


Maintenance Tips

  1. Clean Panels Regularly: Dust, bird droppings, and grime can block sunlight, reducing efficiency. Use soft water and a non-abrasive cloth to gently clean the panels every 6-12 months.

  2. Inspect for Damage: Regularly inspect panels for cracks, broken glass, or loose connections. Damage can result in further degradation and performance loss.

  3. Ensure Proper Ventilation: Panels can overheat if not properly ventilated. Ensure an air gap under rigid panels, especially in hot climates, to maintain efficiency.

  4. Check Electrical Connections: Ensure that MC4 connectors and wiring are secure and protected from water ingress to avoid corrosion or short circuits.


Long-Term Performance

Even after 25 years, well-maintained solar panels can still operate at 75-85% capacity, continuing to power your campervan. Brands like Renogy and Victron Energy offer warranties covering performance over decades, making them reliable long-term investments​​.


Conclusion

And there we have it! What an adventure that was... I truly hope you found this article to campervan solar panel installation useful!


Don't forget to subscribe to The Van Conversion Newsletter for everything you need to get started with your own van conversion (I'll send you a free wiring diagram when you join).


If you're looking for some guidance with your van conversion, you might be interested in our book Roaming Home, or in our online course The Van Conversion Mastery Course. You'll learn directly from me how to convert a van into your dream home - no prior experience needed!

van conversion electrics course

Until next time,

Shane ✌️


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