Building and installing a van life solar setup is not terribly difficult or expensive. If you’re looking for information on how to build a solar system for your campervan you’ll find everything you need in this post!
In van life, there is nothing like complete independence from any utility you would find in a brick and mortar home. After all, much of the reason why many of us choose van life is to escape the confines (and bills) that come with a house, condo or apartment.
This is called living “off-grid” and can be achieved relatively easily and affordably with considerations for your campervan water system, propane system and electrical system. Part of your electrical system may involve the addition of a solar system.
When solar technology was first being developed it was expensive, inefficient and complicated to install and setup. But twenty years into the twenty-first century solar components are affordable, efficient and mostly plug and play.
We’ve installed and upgraded numerous solar systems in over four years on the road and we’re excited to help you understand the basics of what you need to consider when planning for solar in your van.
Like the other core systems, proper planning will save loads of time and money when it comes to the installation of your solar system on your van conversion.
DISCLAIMER: Building a solar system in your campervan can be intimidating. We definitely recommend that you consult professionals for anything you do not fully understand or need help with on the installation. This post is intended to give you the outline and basic guidelines for how your solar system works, what components you need to consider including in your setup and the basics of how to install these components. It is not intended to be an actual guide or installation manual as we are NOT electricians.
AFFILIATE DISCLAIMER: This post contains affiliate links for products and services we recommend. For more information, read our full affiliate disclosure here.
Solar Power Options on a Budget
We’ll go into more detail in the post below to describe each of these components that you need to consider when designing and installing your van’s solar system.
But we want to give you a few ideas of different versions you could use as the framework for your van’s solar power needs based on your budget.
Bare Bones Van Solar System (Under $1,000)
You likely won’t want to leave on a road trip of any duration without adding solar power to your van. So at the bare minimum, we’d recommend you consider this as the basis for a bare-bones approach to solar power in your van.
CHECK DISCOUNTED PRICE
- 100W fixed rigid panels or flexible solar panels
- + 20 amp PWM charge controller
- 140 Amp Battery Isolator
This will give you the ability to slowly recharge your battery bank – whether you consume only a little power or if you have alternative ways to charge your battery (alternator, shore power, generator).
You could also opt for a portable suitcase panel option if you did not want to mount solar panels on your van. But while these offer some advantages, they are less efficient and you have to lug them in and out every time you want to use them.
Middle of the Road Campervan Solar System (Under $1,500)
If you’re looking for a middle option to upgrade your solar to something more reasonable without blowing out your budget, this is a setup that we’d recommend you consider investing in.
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- 200W fixed rigid panels or flexible solar panels
- 40 Amp MPPT charge controller
- 140 Amp Battery Isolator
- Connected in parallel
This leaves plenty of room to be able to add solar panels later if you decide you need more power delivered back into your batteries.
The Ultimate Van Life Solar System (Around $3,000+)
Now we’re outlining what we think would be a pretty awesome solar setup for van life if you have high energy consumption and/or if you don’t want to ever think about how much electricity you need (or having to plug into shore power) again.
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- 300-400+ watts fixed panels (rigid monocrystalline panels)
- 30-40 amp MPPT charge controller
- 40 amp DC-DC Charger
- Connected in series-parallel
- With the ability to add a portable solar input to your system so you can have the option of adding additional solar potential later.
Note that with this system you could go even bigger from the base. We’ve seen vans with solar panels mounted both on top and on either/or/both sides of their van. And we’ve seen others with their entire roof covered to the brim with tilt-mounted solar panels.
Knowing our above-average power consumption and our desire to always have enough power without having to worry about it ever again, we wouldn’t plan to hit the road with less than this 400W/40 amp MPPT controller option.
An Overview of A Van Life Solar Setup
There are a few things to understand about solar power and your van’s electrical systems. We’ll cover the basics below before we get into the details of how to build your perfect solar setup for van life.
How does a van solar system work?
In its simplest explanation, a solar system works by collecting sunlight and transferring it to your battery or battery bank. While it seems simple, the process is a little complex and involves several key components in order to operate safely and efficiently.
Solar Panels – Solar panels are typically rectangular in shape and made up of a combination of glass and metal. As sunlight reaches the solar panel it absorbs the radiation and converts it to usable energy that can be transported into your van.
As with all power, this transmission contains the energy of a particular voltage and amperage. You can manipulate how much voltage and amperage reaches your battery through the use of a charge controller.
Charge Controller – A charge controller is connected both to the solar panels and the battery bank. As such, it acts as a “middleman” in the process.
It accepts the energy transferred through wires from the solar panels and delivers this to the batteries in an amount and force that protects the battery’s health. And it also acts as a barrier to prevent energy stored in the battery from flowing to the solar panels at night.
You will need to have these 2 components in order to safely and effectively harness energy directly from the sun. But you will also need various wires, fuses and wire terminals to connect the system.
You will find information about all of these components in the section below.
Solar systems work as follows:
First, energy from the sun comes in contact with a solar panel. The solar panel absorbs the radiant energy and converts it into 12-volt electricity.
Next, this electricity flows through wires to the charge controller. The controller evaluates the battery state of charge and determines how much solar energy is required and at what force. It will then change either the voltage and/or the amperage of the solar energy to feed the battery accordingly.
Finally, the usable amount of solar energy is delivered to the battery from the charge controller. Excess energy not needed in the battery is redirected back to the solar panels to be returned to the atmosphere as heat.
Components Required In A Solar Panel System
Before we cover the basics of a campervan solar power system we want to go through what the most robust solar setup may look like for a van. From there you can determine which components you may or may not want to include.
Although we will cover each of these components in more detail below, these are the different appliances that you will want to consider when planning your campervan solar electrical system.
- Solar panel(s)
- Solar charge controller
- Mounting brackets
- Cable entry gland
- Fuses / Breakers (optional)
- Branch connectors (optional)
When it comes to mounting and installing these components the job will be divided between work done on the roof and work done inside the van.
Work on the roof will entail mounting the solar panel(s), connecting them (if necessary), adding a fuse and installing a cable entry gland to run the wires inside your van.
Work done inside the van will include both properly fusing and connecting the wires on both ends of the solar charge controller.
When it comes to having the best solar panels you can fit on your van and into your budget, you’re going to want to consider three sets of decisions.
Buying solar panels can be a bit overwhelming. But if you keep these decisions in mind, you are sure to end up with the right van solar panels for your setup.
Polycrystalline Solar Panels vs Monocrystalline Solar Panel
When it comes to the decision between a polycrystalline solar panel and a monocrystalline solar panel, we believe that you will want to look exclusively at monocrystalline panels.
A monocrystalline solar panel is more efficient and has become the industry standard when it comes to traditional solar panels in a van solar power setup. They have a black color (as opposed to a darker blue) and can typically collect a larger amount of solar energy in a much smaller space than polycrystalline solar panels.
Fixed vs. Portable Solar Panels
You’ll also want to decide between fixed versus portable solar panels. Fixed panels are most common and you will see numerous vans with solar panels permanently mounted on their roofs. But portable solar panels offer advantages too.
A fixed solar panel setup is efficient, sturdy and can endure brutal weather conditions making them a popular choice. But they do require some additional steps in the installation. And if you ever want to swap them out later it may be more difficult depending on the dimensions and how you have mounted them.
On the other hand, portable panels typically come in solar kits where they fold out and can be propped up within a certain wiring radius of your van. The solar panels collect direct sunlight and then transfer it into your van in such a way that you could park your van in the shade and still have access to great solar power.
However, portable solar panels are usually not as efficient as fixed solar panels and it can become tedious to have to pull them out every time you want to use them. Plus you are only benefitting from solar power if you have the portable solar panels out.
On the other hand, fixed panels will always be generating solar power for you as long as the sun is shining.
Rigid Solar Panels vs. Flexible Solar Panels
One final decision to make about solar panels is whether you want rigid solar panels or flexible solar panels. Rigid solar panels are as they seem. They are firm, sturdy and typically constructed with a thick aluminum frame.
On the other hand, flexible solar panels are thinner and more lightweight. Flexible solar panels are often more affordable and they can fit the curve you may have on the roof of your van a little better than rigid solar panels.
But most people in van life opt for more durable and efficient rigid solar panels. They are a little bulkier. But their higher efficiencies and the fact you don’t have to worry about whether or not they can survive adverse weather make up for it in the long run.
READ MORE: For more information on understanding how solar panels work and what to look for when choosing the best solar panels be sure to check out this post.
Solar Charge Controller
The next component you need in your solar power setup is a solar charge controller. The charge controller acts as a “middleman” between your battery bank and your solar panels. As the middleman, a charge controller performs two primary functions.
First, they ensure that energy from your solar panels is delivered to your battery bank at an acceptable voltage and amperage to maintain consistently healthy battery life. Any additional energy collected from your solar panels but not needed in the battery bank is redirected by the charge controller to be released into the atmosphere from the solar panels in the form of heat.
The second important thing that a charge controller does is to ensure that power stored in your battery bank does not flow “backward” to the solar panels during the night.
If you connect your solar panels to your batteries directly without this charge controller acting as the middleman then you can count on catastrophically damaging your batteries through both overcharging and draining them overnight.
When it comes to charge controllers you have two decisions to make.
PWM vs MPPT Solar Controller
PWM or “pulse width modulation” controllers are primitive and less efficient than their more contemporary counterparts. As such, we don’t really advise shopping for a PWM controller. While they are more affordable, they are far less efficient and only work well in a simple solar power system.
On the other hand, MPPT charge controllers are highly efficient, with as much as 99.5% of the solar energy collected by the panels being transferred to your batteries. They are more expensive than PW controllers.
But their efficiency alone makes up for the cost in the long run. Plus they also work well with more advanced batteries such as AGM and lithium.
Charge Controller Size
You will see that almost all charge controllers have a number in front of their name rating the amperage of that controller. For example, one of our favorite charge controllers is the 40 amp MPPT controller offered by Renogy.
What this means is that the charge controller is able to transfer energy from your solar panels up to a 40 amp flow. In other words, if your panels were capable of transferring energy at 50 amps into your controller, the controller would regulate the amperage and drop it to 40 amps delivered to your battery bank.
Since vans have limited roof space it is likely that most solar setups will only need a 30 amp controller at maximum. But you will want to assess this based on which solar panels you select and the current they generate combined when connected in parallel and/or series.
READ MORE: For more information on understanding how solar charge controllers work and what to look for when choosing the best charge controller be sure to check out THIS POST.
The next consideration for your campervan solar setup is the hardware you will use to mount the solar panels. The most common mounting method is to use “z-brackets” like these to connect your solar panels to your roof.
This creates a flat surface when installing solar panels parallel to your roof and is common because it is simple. Some people will mount aluminum utility railings to their roof and then mount the solar panels to the railings using the Z brackets.
But the simplest installation option is to just screw the Z brackets directly into the roof. To do this you simply place some butyl tape beneath the bracket, drill self-tapping screws into the Z-brackets and then add some self-leveling lap sealant to cover up the screw holes and make the roof watertight.
Some people will opt for more complicated tilt-mounting solar panel installation that will allow them to prop their solar panels at an angle to collect more direct sunlight when the sun is shining at lower angles, such as in the morning and evening hours.
There is special hardware for tilt-mounting that you will want to use if you opt for this route. Generally speaking, the amount of energy gained from tilt-mounting is not so much that it is worth going through the additional effort.
But this option does allow you to collect more solar energy from conventional solar panels if you are a big power consumer in your electrical system.
Cable Entry Gland
While not necessary, we recommend using a cable entry gland as a protective barrier between the wiring on the roof and that inside the van.
It is a simple cover that allows you to bring wires from the solar panel junction box into the cable entry gland from your solar panel array through a watertight connection, then through the hole in your roof where you run the wires into the van.
Cable entry glands are very affordable and are designed to be aerodynamic when installed on your roof. The alternative option is to simply cover the hole you drilled to run the solar panel wiring into your van with enough lap sealant that you feel comfortable knowing that water will not enter.
Personally, we prefer the peace of mind that the cable entry gland provides and use it on every one of our solar installs.
Fuses / Breakers
There are several types of fuses you will want to consider depending on how complex your solar setup is and how much power you draw through your electrical system. The purpose of a fuse is to “break” in the event too much current passes through it. With solar power in your van, you are working with 12 volt DC power, which flows in a loop.
If a fuse receives too much power in this loop then it will break the loop and energy will not flow. The purpose of a fuse is to protect all components, devices or appliances connected to the power source. You always install fuses on the positive wire in the circuit.
So if you have multiple solar panels, you will want to install an in-line fuse like this on the positive connection between the two panels you are connecting. This creates a protective barrier to the charge controller.
On the other side of the charge controller, between it and the battery bank, you will also want to install a properly sized in-line fuse to protect both the battery bank and the charge controller from any power surge.
We prefer to use breakers instead of fuses, as they do exactly the same thing. However, a breaker has a switch that you can open (to stop power flow) or close (to start power flow) with the press of a button.
These are bulkier, but far more convenient. Instead of having to check the fuse and go through the effort to replace it, you simply close the breaker to reset the solar power system. Be sure that these are properly sized as well to match your solar panels and charge controller.
Note, you may also opt for a breaker between your battery bank and your inverter for the same reason.
Branch connectors (optional, depending on number of panels)
Branch connectors are simple devices that allow you to connect multiple solar panels together. You can have your multiple van solar panels wired in either series, parallel or series-parallel depending on your goals and needs. Read more on this kind of connection here.
But anytime you need to bring two wires from two different solar panels together, you can connect them using a branch connector. There are branch connectors that accommodate anywhere from 2 to 4 solar panels.
So if you are only installing one solar panel you will not need to consider a branch connector.
Best Practices For Designing Your Van’s Solar System
When it comes to designing your van’s solar setup and electrical system, you’ll want to consider some best practices that will make your setup safer and more efficient.
As an optional sub-system of your electric system, you will want to put the same effort into proper wiring and installation with your solar setup as with another wiring inside your van.
These are the top things we’d recommend that you consider when designing your solar.
Have an idea how much power will you reasonably need.
One of the most common issues with campervan solar setups is not knowing how much solar power you need. We’ve seen too many van dwellers put way too many solar panels on the roof for either the battery bank and/or overall power consumption in the van.
For example, having 600 watts of solar panels for a battery with 100 amp-hours of usable battery capacity with a 2000 Watt inverter is not ideal.
On the other hand, having too few watts of solar power for your power needs means that you may damage your batteries if you cannot recharge them fast enough to keep up with your power usage.
If this is your first step into van life and you have no idea how much power you will use, consider this resource to help you understand how much power different devices require.
Then think about your design and how often you’ll use selected devices. A common recommendation we make as a starting point is to plan for lithium batteries with 200 amp hours of usable capacity 300-400 watts of solar panels.
But this will vary more or less on your personal power needs, but presently and any you foresee in the future.
Consider series vs parallel vs series-parallel wiring.
There are advantages and disadvantages to each, which is covered in more detail here. Essentially you have options when connecting 2 or more solar panels together.
Wiring your solar panels in series will double the output voltage but keep the amperage the same. This will allow you to use thinner wires as the flow of power between your solar panels and the charge controller remains at a lower overall amperage.
On the other hand, wiring your solar panels in parallel will double the amperage but keep the voltage the same. You have to keep an eye on how many solar panels you connect in parallel because the extra power from the solar output may have too much amperage for thinner wires.
A series-parallel connection is a perfect combination of both, particularly if you plan to have 4 or more solar panels on your van (not entirely common in van life).
Most van solar power setups will use parallel connections (collecting all the positive wires in one branch connector and all the negative wires in another branch connector) because they will only involve 2-3 solar panels.
But if you have the roof space to consider 4 or more traditional solar panels then you will want to study the advantage of series-parallel connections as a way to reduce both the thickness of the wire you should use and the distance you can run the wire between the solar panels and the charge controller.
Aim for the shortest wire runs possible.
Energy is lost in transfer the longer distance it has to travel. And while in small spaces like a campervan, this loss is likely negligible. However, you still don’t want to design an electrical system where your solar panel wiring enters your van in the front and then has to have wiring travel the length of the van to your charge controller in the back.
Try to design your solar set up such that you can drop the wires from the solar panel to the charge controller as directly as possible. Likewise, make the wire run between the charge controller and the battery bank as short as possible as well.
This keeps your electrical systems safe as well as efficient.
Don’t skimp on heavy gauge wire where necessary.
You’re likely going to spend tens of thousands of dollars on a legitimate van build. So when it comes to wiring safety, don’t skimp out on the cost of heavier gauged wire for your campervan solar power setup. You won’t have to go with anything too crazy.
Most wires between solar panels and controllers are 10 AWG, which suffices for most setups. But between the controller and the batteries you may want to invest in either 6 or 8 AWG gauge wires depending on the size of your solar panel array and charge controller.
If there is a connection between a power source and an appliance (especially an expensive appliance), you’ll want to add a fuse. With your solar power setup, you’ll want to fuse between the solar panels and the charge controller and between the charge controller and the battery bank.
Additionally, if you have any appliances or devices running directly off your battery that may bypass your DC power distribution center (with its own fuses for each associated device) then add a fuse. This is most practical with an inverter connected to your battery.
But if you run an appliance on alligator clips to your battery (such as an air compressor or lighting) you should have a fuse between the appliance and the battery. Remember, a fuse (or breaker) goes on the positive wire.
Leave option for additions later (or suitcase addition).
Nobody gets van life right on the first try. In fact, we’re constantly studying other vans and RVs and looking for ways to improve our setup. One of the best things you can do with your solar setup leaves room to expand your electrical system.
So you may start out with a smaller 20 amp PWM controller and 100-watt solar panel because it is very affordable. But if you upgrade your system to multiple solar panels you’ll want a larger amperage MPPT controller.
So in this case we’d suggest you start out with the larger controller, say 30 or 40 amp MPPT, and then your system can grow with the charge controller.
The same principle applies to solar panels. You may only start with 1 monocrystalline solar panel and that find you really need 2 or 3. Ensure that where you place the panel(s) on your roof allows you to quickly and easily add additional panels and the necessary wiring, without tearing your roof and electrical system apart.
Tools, Materials and Process for Solar System Installation
We learned how to install our first solar system from watching YouTube videos. But there are definitely things that we did not do as correctly as we could have if we had the right tools and knowledge beforehand.
So hopefully we’ve given you quite a bit of knowledge about the fundamentals of your solar system. Now when it comes to installation, these are the tools you’ll want to invest in to make your installation as easy and watertight as possible.
- 3/4” #10 self-tapping screws
- Drill & Screw Gun
- Butyl tape
- Dicor Lap Sealant
- Heavy duty wire cutters
- Heavy duty wire crimpers
- Solar tray extension cable
- Appropriate gage wire
- Appropriately sized battery lugs
We can’t cover all of the details of solar panel installation in this post as your van setup may vary depending on a wide number of options we’ve presented. However, the basics are the same:
First, disconnect your battery when working on the solar panel installation. You want to prevent any energy from flowing through your electrical system (and into you!) while you are working on it. Do note that 12-volt shock is typically not dangerous. But it will definitely startle you!
Next, cover the solar panels when they are on the roof before you connect the wires to run into the van. Typically you can just use the cardboard box they were shipped in. If the solar panels are not covered and are in direct sunlight during the installation process they will generate energy and want to send it somewhere. So keep them from collecting power until you are ready to test them.
Anything you screw into the roof should have a strip of butyl tape beneath it. This creates a firm seal that will not allow water between the roof and the item you are screwing into the roof. Whether you mount an aluminum bracket or simply screw the Z-brackets into the roof, butyl creates an essential watertight seal.
Any screws or holes into the roof should have an adequate amount of self-leveling lap sealant to ensure water does not enter the van through the roof. You can also consider adding a strip of Eternabond tape over the screws before applying lap sealant around the edges of the Eternabond.
Measure twice, drill once when it comes to bringing the wires from the solar panel junction box into your van. Try and find a place that keeps the wire run as short as possible from the solar panels and that enters the van in an unobtrusive manner (such as into a cabinet or specific part of the wall).
Once you pop a hole in your roof you don’t want to realize that you put it in the wrong place and need to make another hole. You’ll want to only have the 2 solar wires and a dab of lap sealant in the hole. And you don’t want to make the hole too wide. It only needs to be wide enough to bring those 2 solar wires into the van.
Consider using breakers, which you can leave in the “open” position, instead of fuses as an additional safety precaution when installing your solar components.
Connect all positive wires to the charge controller first. This order does not matter, whether the battery or solar wire is connected first.
Then connect the negative wire from the negative battery terminal (or busbar) to the controller first. This ensures a proper connection between the charge controller and the battery prior to any solar input.
After that, connect the negative solar panel wire to the controller second. This ensures that solar energy is not coming into a controller that has nowhere to send the energy, thus causing it to overheat.
If you have used breakers, close the CONTROLLER→BATTERY breaker first to establish the connection between the battery and the charge controller. Then close the SOLAR → CONTROLLER breaker second to allow energy from the solar panels to flow into the charge controller and from there to the battery bank.
Finally, uncover the solar panels to allow them to begin to operate. Head back inside and monitor the charge controller to ensure that power is flowing into the batteries (assuming this is done during daylight).
Frequently Asked Questions About Van Life Solar
Although we hope that we have explained how a solar setup will look for your campervan, there are still some solar frequently asked questions we’ll address below.
Do I need Solar Power for my van?
You need water, food and shelter. But you don’t need solar. However, solar panels, charge controllers and other tools and equipment for installing solar is so reasonably affordable that you will find very few van dwellers who do not have at least one panel on their roof.
There are alternative ways to keep your batteries topped off. In van life, the most common method is to use your vehicle’s alternator to provide additional energy to your house batteries while you are driving.
You could also install a shore power connection as part of your van’s electrical system and plan to plug it in every so often. This could be at a campground (where you may also find a hot shower and maybe laundry facilities) or at a friend’s house.
The less common option for van life, but common among other RVers, is to have a generator that acts as your portable shore power.
But back to whether or not you need solar for your van. The absolute answer is “no.” But we’d recommend that you at least consider the idea of leaving roof space for later addition if you find that you do need solar to keep up with your power consumption on the road.
An even better option would be to opt for a middle-of-the-road solar kit that has everything you need for a quick installation.
This kit is our top recommendation for a simple, affordable solution for solar. With 200W of potential power, this would pair well with 100Ah of usable battery capacity (100 Ah lithium battery or 200 Ah gel of AGM battery).
And the 40 Amp MPPT controller is more than enough to be able to add more panels later and not need to upgrade your charge controller.
The panels are sized to fit in pretty much any orientation you would need them to be installed on your roof. And the installation is pretty straightforward with such a basic kit.
But, if you are on the fence about whether you need to add solar panels to your van, and you are coming down to the “last dollar” in your van build budget, we would recommend that you spend that last dollar on your battery bank rather than on solar.
Having a larger, particularly lithium, battery bank will serve you better in the long run. You will likely be able to keep the batteries topped off through frequent driving. And with a large lithium battery bank, it is not likely you’ll ever risk using up all of the battery capacity before you find some way to top it off.
READ MORE: If you’re looking to spend that last dollar in building a better battery bank be sure to read this post on what to look for and our best recommendations for campervan batteries.
How much does it cost to set up solar on a van?
The cost of a solar power system for a van varies from a few hundred dollars to a few thousand depending on a variety of factors. The major factors include what kind of solar panels you choose, how many you want to install and the quality of your charge controller.
Each of the required individual components varies in cost by their own factors, which we’ll explain in more detail.
You should expect to spend between $500 – $1,000 for a reasonable solar setup for your van. Of course, you can go higher or lower if your budget requires or permits.
Decent solar panels will likely range around $1 per watt. So expect a range in prices for a 100W solar panel to be around $100. Most vans equip themselves with at least 2 solar panels.
Charge controllers will vary in price as well. You can expect to spend anywhere between $75 – $300 for a decent charge controller for your solar power system.
And then there is some hardware and wiring in between that will cost between $50 – $100 or more.
You can often find solar kits that will bundle a wide range of solar panel wattages with all of the other required components. Solar kits will run between $500 – $1,000 or more depending on the brand, kind and size of the solar power system.
Which solar panel is best for van life?
The best answer to this question, from our perspective, is any monocrystalline solar panel that is properly connected to a working charge controller. Several years ago there were only a handful of manufacturers in the solar panel space.
This meant your options were fewer both in panel sizes and brand. In 2022, there are dozens of brands with many different kinds, styles and sizes of solar panels.
We put together a great post on our top recommended solar panels. You can read that post HERE.
In short, we’re big fans of this 100-watt monocrystalline panel from Renogy. We’ve used them on every RV we’ve owned or worked on since we began living nomadically in early 2018.
And if you read on to the section below about how much solar do I need for van life you will find we use it as our example because it is a solid choice to rely on for your campervan solar setup.
But there are other great options as well if you want to shop around. Be sure to check out our post on the best solar panels or stick with our top recommendation.
How much solar do I need for van life?
You can’t really have too much solar power for your van. But you can have too little. Actually, you don’t actually NEED solar in the first place. While it is a very common addition to most campervans, it is a luxury and there are plenty of ways to get around adding solar to your van.
However, if you want to calculate the exact amount of solar panel wattage that you need then you will need to do some experimentation with your appliances as well as some basic math.
But before you grab a pen and paper and head out to your van (or use your imagination), there are 2 basic rules of thumb that you could use to estimate how many solar panels you need.
- Assume 100W solar panel provides around 30 Ah per day, or
- Match your battery capacity in solar panel wattage + a little overage (Ex: 200 Ah battery bank = 200W solar + 50W extra = 250W solar)
The first rule of thumb is a little more precise and supported by math, so now lets dig out that pen and paper and head to the van.
Power is stored in your battery in a quantity known as Amp Hours. Flooded lead-acid batteries and lithium batteries alike will be rated in Amp Hour capacity. One amp hour is the equivalent of powering a device that requires 1 amp to run for exactly one hour.
A common battery size is 100 Ah. If you have a flooded lead-acid battery, you should never use more than 50% of this capacity. If it’s AGM, you can use up to 60% and lithium you can use upwards of 80-90%.
Assumption: So let’s assume that you have 100 Ah of usable battery capacity in your battery bank. This could be one 100Ah lithium battery or 2 x 100Ah AGM (note, we don’t recommend flooded lead-acid batteries for van life).
So here’s where the calculations come to play. You will want to know how many amps it takes to run each appliance in your van before you can calculate how much power you use, and would thus need to replenish, with solar power.
If you have a battery monitor, this process will be simple.
- Simply switch on an appliance and see the draw in amps that come off the battery. Do this for every device you would possibly run at any time in your camper. (You can use this cheatsheet from GoPower if you want to try and skip some steps. But note they don’t tell you how many you need, just which product of theirs to buy.)
- Next, estimate the number of hours you would operate the appliance. Multiple its amp usage by this number of hours to get the total number of amp-hours the appliance would consume from your battery during the course of one day.
Assumption: A Fan-Tastic fan may draw 2 amps on its middle setting and you will run it for 10 hours overnight.
2 amp/hr x 10 hrs = 20 amp hours of consumption
- Do this for every appliance to get an idea of the total number of amp hours you would use throughout the course of the day.
Assumption: Let’s assume that your total power consumption is 80 Ah from your usable battery capacity.
To keep your battery bank healthy you will need to offset this use by adding back that same amount of power from other sources. This could be shore power, a generator, your alternator or solar power.
At this point, you will want to look into various solar panel options and determine their maximum solar output in amperage and voltage. Read the “specs” section of the item description.
For example, a single 100-watt Renogy monocrystalline panel can provide approximately 5 amps at 20 volts. Power (in watts) is equal to current (in amps) times voltage (in volts).
So 100W = 5A x 20V checks out.
This means that in perfect conditions, you could recover approximately 5 amps per hour for every hour of sunlight. Unfortunately, we’re never in perfect conditions when it comes to solar panels, so a general principle is to use the amps rating times 6 hours of sunlight.
ASSUMPTION: In this example, a 100W panel can generate 5 amps x 6 hrs = 30 Amp-hours.
So if you calculated that you consume 80 Ah per day using all of your various appliances, you simply divide this number by the 30 Amp-hours you collect through your solar panels.
80Ah / 30Ah = 2.66 solar panels (100W solar panels)
Because conditions are never perfect, we’d recommend that you round up to at least 3 x 100W solar panels in this situation.
Note: A common setup in van life is to have around 200 Ah of lithium batteries with approximately 400 Watts of solar, or a 1 to 2 ratio.
Hopefully, we’ve helped you understand the basics of each component you need and how they function in a basic van solar setup. You can build as large a solar panel array as you can fit on your roof and combine fixed with portable panels to create an even larger solar array.
Or you can keep it simple with just portable solar suitcases as your basic solar setup. How much solar you need depends on how much power you anticipate drawing and what other methods you may plan to recharge your batteries.
But regardless of however much solar you choose, we think you should definitely plan to incorporate a solar setup into your van build.
Christopher Harvey is the founder and primary content creator for Called To Wander and Van Life Movement. He lives and travels full-time in his RV with his wife Lindsay and their two Australian Cattle Dogs. Passions include helping other people understand how to life a nomadic RV lifestyle and studying and planning an epic van build to drive the Pan American Highway in 2023.