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Last Updated on April 26, 2022 by Jessica Lauren Vine
Do you wonder how to install solar panels on an RV?
Installing solar panels, or a solar system, on an RV can be a simple DIY task involving some basic tools and common construction skills. Installations can range from exceptionally simple to fairly complicated depending on the complexity of the system you are installing and the internal structure of your specific RV.
The most important part of the installation process is formulating an installation plan. In this article, we’ll take a look at how to do that. Because of the broad range of solar options and RVs to put them on I can’t really produce a step by step or bolt by bolt guide.
However, I can cover the basic knowledge you’ll need to put together an installation plan for the most common types of RV solar systems. This will include a look at some specific components to get the job done right.
Before getting into the specifics of a solar installation there are a few basic concepts that you’ll need to become familiar with. You will basically be attaching an electrical power station to your RV.
In doing that it’s critical that you understand that these systems can generate a lot of energy which can be excessively dangerous if not handled properly. Even small systems or individual parts of larger systems can cause serious injuries or start fires. Unfortunately, covering all elements of safe handling and safe design are outside the scope of this article. However, here are some key points you’ll need to know.
Basic Safety for RV Solar Panel Installation:
- Always cover the solar cells of a solar panel with a light-blocking material like cardboard when you are handling or working with them. Any light reaching the solar cells will result in power generation which can lead to shock or sparks.
- Always properly fuse your wires. If a wire is not properly fused then the wire becomes the fuse and that can lead to various dangerous situations.
- Never mix power systems. RVs have AC power and DC power. Solar systems generate DC power which should never be directly connected to the AC system. To bridge the two systems only use components like inverters specifically designed for that task. Always follow the manufacturer’s instructions on how to properly wire those connections.
- Always read and follow the manufacturer’s instructions for any component, part, or product you use in your install.
- If you’re unsure about something, get help from a qualified professional.
Basic Electrical Concepts
There are two basic electrical concepts you’ll need to understand. First is what amps, volts, and watts are, how they are related to each other, and how you use them to select parts that will go in your system. These are the most common electrical terms you’ll come across, and they each play an important role in your system design.
Volts are a measurement of the electrical potential between two poles, usually positive and ground in an RV solar system. As a measurement of potential energy, the higher the number, the greater the potential energy stored between the two poles. Volts are critical because electrical components are designed to operate at specific voltages. Attaching a 12 volt RV refrigerator to a 24-volt battery would likely cause very expensive damage to the refrigerator.
Amps are a measurement of current or the flow of energy between the two poles of an electrical system. The important thing to remember about amps is that they are typically used to size the components in your system. You’ll need to know how many amps will be flowing through your components like wires and fuses so you can choose appropriate sizes for your application.
Watts is a measurement of work which is calculated by watts = amps * volts. In an electrical system, the “load” is the part of the system that is doing work and that load is usually given in watts. For example, a typical RV ceiling light will be a 4-watt load on your electrical system. The relationship between watts, amps, and volts is critical. In this case, a 4-watt load on a 12V system takes 0.33 amps of power (amps = watts/volts). Knowing this, we can wire the light with wire capable of safely handling 0.33 amps of current.
Resistance. One last item to consider is resistance. In DC electrical systems, resistance can play an important role in choosing things like proper wire size. DC current traveling through a wire will always experience resistance. That resistance increases as the wires get longer and/or thinner. Wire runs in an RV solar system can be long enough that it should be considered in selecting proper wire sizes between components. There are a number of resources online which can help you choose your wire sizes like this one for 12V DC systems.
Series Vs. Parallel Wiring
The second important concept is the difference between wiring components in series vs. parallel. This is important for your battery bank, as well as the solar panels themselves. Each method has very specific effects on the overall system as well as specific pros and cons for the overall operation of your system.
Batteries in Series. Batteries wired in series should always be of the same volt and amp-hour ratings. Mixing batteries in a series configuration with different properties will lead to imbalances which will eventually damage your batteries. When wired in series you add the voltages of each battery in the series to get a total series voltage. So two 6 volt batteries wired in series will output 12 volts. The amp hours are not additive. So two 6 volt 200 amp hour batteries wired in series will output 12 volts with 200 amp-hours of capacity.
Solar Panels in Series. Solar panels wired in series behave like batteries wired in series, but you don’t have to worry about balancing issues with mixed panel arrays. Like batteries, the voltages of panels in series are additive, but the current is not. So two 12 volt solar panels that produce an operating current of 8 amps wired in series will output 24 volts with an operating current of 8 amps.
The operating current of a series array of solar panels will actually be limited to the lowest current panel in the series. So if you have a 12V panel running at 8 amps in series with a 24 volt panel running at 4 amps then the series will output 36V at 4 amps. This principle leads us to the major negative of wiring your solar panels in series. If shade falls on one, or for that matter, even on one cell in one panel then the current through the entire panel array will fall accordingly. It is possible to lose power from all your panels with just a single leaf falling on one panel of a series array.
The major advantage of series wiring is that because the current is not additive you can build a larger array with lighter gauge wiring. Lighter gauge wires are cheaper, lighter, and much easier to work with than heavier gauge wires.
Batteries in Parallel. Batteries wired in parallel must all be of the same voltage. While amp hour capacities can be mixed, it is generally considered best practice to have all the batteries in your system have the same amp hour rating too. In a parallel array, the voltages are not additive, but the amp hour rating is. So a battery bank with four 12V batteries with 100 amp hours each wired in parallel will output 400 amp hours at 12V.
Solar Panels in Parallel. For solar panels, the voltage stays the same, but the amps are additive. So four 12V solar panels putting out 8 amps each wired in parallel will output 32 amps at 12V. This is the major disadvantage of wiring your panels in parallel. The higher currents will require larger, heavier, and more expensive wires between your panels and the charge controller. The lengths of those wires can be pretty long on an RV installation, so the costs can add up quickly.
The major advantages of wiring your panels in parallel are that there is a broader range of charge controllers that can work with the lower voltages. Also, shading a single panel will not cut off the current in the entire array.
Mixing and Matching. You can mix parallel and series wired groups together as long as you follow the rules for each type of wiring. So you can have two sets of two 200 amp-hour 6 volt batteries wired in series to give you two 12 volt 200 amp hour sets. Those two 12 volt sets can then be wired in parallel to give you a total 12 volt system with 400 amp hours of capacity.
The larger your system is, the more likely you will have to mix series and parallel wired components, especially on the solar panel side. Putting together a final design will be a balance between keeping voltages low enough that your charge controller can handle them while minimizing current to keep your wiring sizes manageable.
With this basic knowledge, we can take a look at three types of install – basic, intermediate, and advanced.
Wire Choice. Regardless of which type of install you’ll be doing, it is likely that you will do at least some wiring. Choosing the right size of wire is critical, and I provided a link above to help you figure that out. The type of wire you use is also important. It is recommended to always use stranded wire for solar installs in locations where motion or flex may be an issue – like in an RV. Stranded wire is also more flexible than solid wire and will make routing the wire through your RV much easier.
Basic RV Solar Panel Install
For a basic install, we’re going to rely on a solar suitcase to add solar to our RV. Solar suitcases are available from a number of different manufacturers in sizes up to 200 watts. Depending on the size you choose, these can be adequate for powering your RV from a weekend to nearly indefinitely, assuming your power usage is modest. The best part is that you may not need to do too much work or modify your RV.
Most RVs manufactured after 2015 have shipped “solar ready.” This means they have internal wiring already installed that will allow you to simply plug in a solar suitcase to add solar power to your RV. All the wiring from the charging port on the side of the RV to the batteries is already properly sized for the manufacturer-recommended solar suitcases. The solar suitcase has everything you need pre-wired and pre-set to generate solar power. All you have to do is plug it into the RV and set it up per the manufacturer’s instructions, and you’re all set.
If your RV is not “solar ready,” or you want to build your own portable suitcase to save money, you have some options.
Adding a solar charge port to your non-solar-ready RV is pretty simple. It involves installing a solar receptacle on your RV and running the wires back to your battery circuit. The two most popular options are the Furrion Solar Charge Inlet port and the Zamp Solar Sidewall Charge Port. Before choosing one, see which one the solar suitcase you plan to use works with directly. There are adapters for both, but if you can avoid buying an adapter then you’ll be better off.
Once you have the port, you’ll need to find a location for it. DC power fades over distance so locating the port as close to your batteries as possible is generally good practice. Most factory installs are through the sidewall of the RV. If you’re not comfortable cutting holes in the outer skin of your RV then you may consider locating it in a pass-through compartment. The battery wiring usually passes through these compartments and will give you quick and easy access to the circuit.
Make sure all the wiring you add is rated for the amp output of your solar suitcase’s charge controller. Also, be sure to install an inline fuse to protect the wiring between the charge controller and your battery.
Intermediate RV Solar Panel Install
You can take your basic solar-ready install and kick it up by integrating the solar charge controller into your RV’s internal “solar ready” wiring. This retains the benefits of the basic install above while adding a bunch of new benefits. First off, it keeps the install simple. Next, by moving the charge controller inside it is less prone to theft and it becomes directly integrated into your electrical system for easier operation. It also allows you to attach solar panels directly to your exterior solar charge port. Those panels can be free to move around like a solar suitcase or roof-mounted.
As a general rule, this type of install can be significantly cheaper and more efficient than a solar suitcase. Finally, if you decide to go full permanent roof mount later then you’ll just have to drop a wire through the roof and connect it up to your already installed charge controller.
To do this on our travel trailer, I disconnected all the batteries and power to the RV and located the power center. I pulled the power center from the wall and located the wires coming from the exterior solar plug. I disconnected those from the circuits and ran them to the solar in ports of the charge controller that I had mounted right next to the power center. The battery charge port on the solar charge controller was connected to a cutoff switch which was then connected to an empty fuse block on the power center. The cutoff switch allows the solar to be disconnected manually from the battery when the shore power converter is on. To operate the system, we turn off the converter breaker in the power center and turn on the cutoff switch between the battery and charge controller. We then attach the solar panels to the outside port and Viola! – we have solar power. There are a couple of things to note with a system like this.
First, the wiring from our factory charge port and wiring to the charge controller is only designed to handle 20 amps. Your’s may be different, so substitute your value for our 20 amps wherever necessary. To be safe, we make sure the solar panel output that we are attaching to that is less than 20 amps. Each solar panel will show a normal operating current and a “short circuit current.” To keep things under 20 amps we chose panels that have a normal operating current below 20 amps and either use 1 panel, or multiple panels in series. If you recall, when wired in series the voltages will add up, but the amps will be limited to the lowest single panel amp output. When using multiple panels in series, make sure you choose a charge controller that can handle the combined input voltage and do not exceed the acceptable voltage for your wiring or charge port. Also, make sure there is an inline fuse greater than your running amps but less than your wiring rating to protect everything in case of a short. For example, my panels run at 8 amps, and the wiring is rated for 20 amps, so I use a 10amp fuse.
The complete install:
For a complete rooftop install, you’ll need the panels, a charge controller, mounting brackets, wire, fuses, MC4 connectors, a roof port, fasteners, and roof sealant compatible with your roofing system. A couple of things to note about these items:
There are two basic types of panel mounting brackets. Fixed and tilting. Fixed are cheaper but only allow the panels to lay flat above the roof. For optimal solar efficiency, you will want to be able to tilt your panels toward the sun. This is especially true in the winter and/or in higher latitudes where the peak sun will be lower in the sky. If you can afford the difference or plan to rely on your solar system as a primary power source then go with the tilting mounts. To install them, you’ll be putting holes in the roof, so this is a buy once, install once moment, so consider your mounting choice permanent and purchase accordingly.
There are several types of roofs used in the RV industry, and you’ll want to make sure that your fasteners and sealants are compatible with the roofing system you have. To do that, it’s best to contact your RV manufacturer and ask if they have a specific recommendation. Many RV manufacturers now offer pre-installed panels. Your best option will be to use what they use.
The process to install will be to find the easiest path from the roof to your power center. That will allow you to locate where to put the roof access port. Once that spot is located, mark it on the roof and then layout the location of where you want to position your solar panels. From there, it’s simply a matter of installing the brackets, access port, panels, charge controller, and wiring per the manufacturer’s instructions. Make sure all the fasteners are covered with a healthy dose of appropriate sealant to prevent leaks. Dicor tape is typically used to hold down the wiring to the roof between the panels and the roof port.
When doing a complete install like this, do not forget to evaluate your entire electrical system, even if you are not modifying them specifically for the installation. Adding a large solar system can easily overpower your factory wiring and cause serious issues. The most common area will be between your charge controller and batteries, where larger gauge wires may need to be installed. There may be other areas to upgrade as well so make sure you go through your entire RVs systems thoroughly when formulating your plan.
Frequently Asked Questions about How to Install Solar Panels on an RV
Who installs solar panels on RVs?
There are some techs that specialize in it but many people learn to install their RV solar panels on their own.
How hard is it to add solar to an RV?
If you take some time to learn how to add solar to your RV, it’s not as hard as you might think. If you’re not good with these types of upgrades, it might be better to pay a professional.