As those of you who’ve followed us for a while know, we’ve got an extensive solar system on our motorhome consisting of a combination of both types of solar panels: rigid and flexible. When we originally installed the flexible solar panels for our RV, we weren’t entirely sure how they’d perform from day to day, but we’d done a fair amount of research and we were hopeful that they’d become an integral part of a successful solar array… harvesting the solar energy we need to stay off-grid for extended periods.
Our rigid solar panels are capable of being tilted, and that’s a real bonus for power-hungry full-timers like us. But flexible solar panels can do things rigid panels can’t. So, today we’re looking at flexible solar panels for your RV – the benefits, the drawbacks, some important notes, and some of the best flexible panels available on the market today.
- 1) What Are Flexible Solar Panels?
- 2) What is the Difference Between Monocrystalline and Polycrystalline Solar Panels?
- 3) What Are the Benefits of Flexible Solar Panels for an RV?
- 4) What Are the Downsides of Flexible Solar Panels for an RV?
- 5) Can Flexible RV Solar Panels Overheat and What Happens if They Do?
- 6) Can You Walk On Flexible RV Solar Panels?
- 7) How Do You Install Flexible Solar Panels on an RV?
- 8) What Are Some of the Best Flexible Solar Panels for an RV?
- 9) Are Flexible Solar Panels for RVs Worth It?
What Are Flexible Solar Panels?
Flexible solar panels are encased in flexible, slightly bendable plastic. In this way, they differ from rigid solar panels that have their solar cells encased in glass.
The top of a flexible solar panel is clear, allowing the sun to penetrate it, reaching the solar cells and enabling them to produce electricity.
Inside a flexible solar panel, thin electrical wires connect the solar cells to an MC4 or similar connector on one end of the panel. This allows the panel to be connected to another panel (either in series or in parallel) or to the solar controller that sits between the panel and the RV’s battery bank.
What is the Difference Between Monocrystalline and Polycrystalline Solar Panels?
The difference between monocrystalline and polycrystalline solar panels is in the solar cells themselves.
Polycrystalline solar panels contain cells that are made of multiple silicon crystals. They’re less efficient than monocrystalline panels, and also less expensive. If you’ve ever seen a solar panel with blue cells – meaning the top of the panel is blue – you were looking at a polycrystalline solar panel.
Monocrystalline panels have black cells that are made of single crystals. These panels cost more initially, but they’re more efficient than polycrystalline panels at generating solar power. Because a monocrystalline solar cell is composed of a single crystal, the electrons have greater mobility, allowing them to generate a greater flow of electricity.
So, while you’ll pay more for monocrystalline solar panels, you’ll also be getting more efficiency for your money… or getting the same power output in a smaller footprint.
What Are the Benefits of Flexible Solar Panels for an RV?
Solar panels offer a number of benefits in an RV application. Let’s take a look at some of the advantages of flexible solar panels over traditional solar panels for your RV.
First is their flexibility (it is, after all, in their name!). This is actually a very important consideration depending on where you want to locate your solar panels. For example, RV flexible solar panels can bend to follow the curve of an Airstream or other RVs with curved roofs.
Some RVs have limited rooftop space for solar panels, and flexible panels can be easier to maneuver around space constraints. Even folks with very large rigs who want to maximize their ability to install solar panels at various angles benefit from the flexibility of RV flexible solar panels.
For example, our dear friends Tom and Caitlin Morton (of Mortons on the Move) installed 10 flexible solar panels on the roof of their fifth wheel, and 2 additional flexible panels on the front cap of the RV. You can read all about their off-grid solar panel installation, but they’ve found that in the shorter days of winter (when the sun is low in the sky), the panels on the front cap are particularly helpful. The flexibility of their stick-on flexible solar panels is the reason they were able to install panels in that location at all.
We installed our flexible solar panels on the roof of our motorhome because, with everything else we’ve got mounted up there, we needed some thin, light, flexible solar panels to share the space.
So, the flexibility of flexible solar panels makes them incredibly versatile.
We should note that flexibility can be a drawback as well. Overbending a flexible solar panel can damage the solar cells dramatically, so care needs to be taken when handling them prior to, and during, installation.
Flexible solar panels weigh considerably less than rigid solar panels, another significant advantage.
All RVers work to keep the weight carried by their rig down in any way possible. Flexible solar panels can weigh as much as 80% less than rigid solar panels, which is a very significant weight difference. And that difference can allow you to install a larger solar array on a smaller RV that doesn’t have the weight carrying capacity of, say, our large Class A diesel pusher.
Easy to Install
Flexible solar panels are very easy to install. Many actually come with an adhesive backing, but either way, the installation of flexible solar panels is a breeze. You simply clean the area where the panel will lay, stick the panel down (avoiding any uneven surface that could affect the adhesive’s ability to stick), and surround the edges with a good sealant tape like Eternabond. That’s it!
There’s no easier way to install solar panels on your RV.
Fewer Holes Drilled/No Mounting Brackets Necessary
Another advantage to flexible solar panels for your RV is the fact that fewer holes need to be drilled into the roof because no mounting brackets are necessary for the installation. And the fewer holes we put in an RV, the better.
In general, an array of flexible solar panels will probably require a single hole drilled, for at least one pair of wires to enter the interior of the RV and connect to the solar charge controller. This of course depends on your particular installation. There are RVers out there (particularly those with self-built camper vans) who’ve installed flexible solar panels without drilling a hole at all. And many other RVers take advantage of the roof vent for their RV refrigerator to run the solar wires into the RV without drilling any new holes.
But generally speaking, most installations will find a single hole drilled for wiring, and that’s all. This is a significant advantage over multiple mounting bracket holes being drilled for rigid panel installation.
What Are the Downsides of Flexible Solar Panels for an RV?
As with anything else, there are downsides to using flexible solar panels, and it’s up to the individual RVer to determine whether the upsides outweigh the downsides or vice versa, based on their particular application.
Let’s take a look at the disadvantages of flexible solar panels for your RV.
In general, flexible solar panels are slightly less efficient than rigid solar panels. This is because flexible panels are so thin that they contain far less material for sunlight interaction/absorption. Due to the thin design of a flexible solar panel, the silicon wafers are pared down to a width of just a few micrometers.
Flexible solar panels also tend to use less efficient semiconductor materials, so they’re not as efficient at turning sunlight into electricity. While rigid solar panels have roughly 16-20% efficiency, flexible panels by comparison have anywhere between 7 and 15% efficiency. This of course depends on the panels, their placement, and other factors, but it also means that each flexible panel gives you less energy than a similarly sized rigid panel, so you’ll need more/larger flexible panels to get the same amount of energy you’d get from a rigid panel.
Due to the fact that there’s no airflow under flexible panels that are stuck directly to the roof, there’s less heat dissipation. So the solar panels themselves get very hot. Solar panels can get as hot as 150 degrees during the summer, depending on your location. And because hot solar cells don’t perform as well, this impacts the solar efficiency of flexible panels even further.
Our Xantrex Flex Max 165W flexible solar panels are electrically almost identical to the Xantrex 160W rigid panels we installed alongside them. Under identical conditions (lighting, temperature, wind, sun exposure, etc… including tilt angle, since we have the ability to tilt our rigid panels), the flexible panels output approximately 5-10% less power than the rigid panels do because of the heat buildup on the flexible (even when not tilted, the rigid panels sit about 1-2″ above the roof surface, allowing air to flow beneath them).
Additionally, that accumulation of heat can, over time, reduce the lifespan of the panels themselves. So flexible solar panels may not last as long as a traditional glass panel would in the same situation/conditions.
Heat retention can also be an issue on the surface where the dark flexible panels are mounted, creating a situation where heat is pulled into the RV on hot summer days (some people worry about the potential for that heat to damage the underlying roof material, but we haven’t heard of any instances where that’s been the case).
Some RVers try to mitigate the heat issue to some degree by installing their flexible panels using various techniques (velcro, PVC piping, etc) in an effort to allow the panels to dissipate some heat while still holding the panel securely to the surface. But all of that additional work/effort is undoing much of the benefit of the ease-of-installation of flexible panels.
The durability/lifespan of flexible solar panels tends to be decreased as compared with rigid panels, which means that you may be more likely to have to replace the flexible panels before you’d need to replace rigid ones.
This may or may not be an issue for you, and most RVers who install flexible panels probably don’t worry much about the lifespan issue. In general, rigid solar panels are projected to last anywhere from 25-40 years, while flexible panels might last 15-25 years by comparison, (although flexible panels are relatively new to the market, so we don’t have as much real-world data to know for sure how long they’ll last).
Flexible solar panels are more costly to buy than their rigid counterparts, mainly because the technology used to produce flexible panels is newer. You could, in fact, pay 2-3 times as much for a flexible solar panel as you would for a rigid solar panel of the same power output.
With that said, the installation of flexible solar panels is likely to be less costly than the installation of rigid solar panels unless you contribute all of the labor yourself either way.
Can Flexible RV Solar Panels Overheat and What Happens if They Do?
Flexible RV solar panels can indeed overheat. Generally speaking, however, they’re tested to withstand very high temperatures and should be perfectly fine in virtually all situations. But it IS possible for a flexible panel to overheat to the degree that the plastic laminate can burn.
This is in addition to the loss of power and the reduction in voltage values that will result from overheating.
Can You Walk On Flexible RV Solar Panels?
It is not recommended to walk on flexible RV solar panels, regardless of what the manufacturer may say. Scratching/scuffing of the surface will reduce the efficiency of the panel by reducing the amount of light that reaches the cells. And the stress of your weight can crack the solar cells themselves, potentially significantly reducing the output of the entire panel, or causing it to fail altogether.
How Do You Install Flexible Solar Panels on an RV?
There are several different ways to install flexible solar panels on your RV. Generally speaking, most people use one of the following methods of installation.
As we mentioned above, many flexible solar panels for RVs come with an adhesive backing already installed (ours did). This makes installation a breeze.
With this method, a commercial-grade/industrial strength Velcro is used to adhere the panels to the surface. This method can allow a bit of airflow under the panels as it lifts part of the surface of the panel off the roof to the degree of the thickness of the Velcro. But it also means that water and dirt/debris can get underneath the panels as well, leading to the potential for mold/mildew to grow.
The edges of some flexible solar panels have rivets that allow for the panels to be screwed into the roof. Some people may prefer this method of installation, while others would prefer to avoid making any unnecessary holes in the roof.
3M VHB Adhesive Tape
Once the surface has been cleaned and prepared for installation, VHB tape is laid in place and pressure applied to create a good seal (fair warning – removing the VHB tape is not for the faint of heart!). VHB tape comes in various widths and lengths.
Eternabond is another very strong tape used by many people who install flexible solar panels on RVs. This tape forms a very strong bond and can be laid around the perimeter of the flexible panel for a solid seal. (Removing Eternabond also requires heat and some fairly heavy-duty elbow grease to remove, so plan accordingly.)
Once the panels have been successfully installed on the surface, you’ll need to connect them (if you’re installing more than one) and create an entry for the wires to be directed into the bay or area where your solar charge controller is located. You may or may not need to drill a hole for this purpose, because you may have an inlet nearby through which you can feed the wires (like your RV’s refrigerator vent).
Finally, you’ll connect the wires to a solar controller which will then be connected to your battery bank.
This process is made more or less complicated depending on how many solar panels you intend to install, but we’ve got a pretty hefty 1,300-Watt solar system, and we did our own installation with the help of our friend Brian of RV with Tito who has some great solar installation videos on his site.
Here’s our ultimate 8-panel, 1,300-Watt solar system explained, but remember – we’re full-timers who live and work off the grid regularly, so we need a robust system.
What Are Some of the Best Flexible Solar Panels for an RV?
Xantrex Flex Max 165W Solar Kit
These are the flex panels we have. While they definitely come at a premium cost, they’re extremely well-made, efficient, and durable. They’re more robust, thicker, and sturdier than any other flexible solar panels we’ve ever seen, by far.
These panels have peel-and-stick adhesive nearly to the edges and don’t require any additional taping with Eternabond, VHB tape, or any other adhesive.
We’ve experienced no issues with water, nor have the panels experienced any loss of adhesion in the thousands of miles we’ve driven, and the numerous rainstorms we’ve experienced, since installing them.
We’ve been very pleased with these panels and their output. They’re working very well for us and, after several years of full-time exposure to the sun and elements, show no signs of aging or degrading.
Xantrex offers a 5-year product warranty.
Renogy 100 Watt 12 Volt Extremely Flexible Monocrystalline Solar Panel
This is an ultra-lightweight, ultra-thin, highly flexible 100-Watt panel that is particularly good for curved surfaces due to its flexibility. The panel is textured to better capture sunlight instead of reflecting it.
Renogy has a very good reputation in the industry, and reviewers regularly comment on the excellence of their customer service.
Of note, Renogy offers a 5-year material and workmanship warranty along with a 25-year 80% power output warranty.
- [Extremely Flexible] This flexible solar panel is capable of meeting a wide range of applications where standard panels can be inconvenient to mount,...
- [Ultra Lightweigh] Thanks to advanced polymer materials, these flexible solar panels weighs 70% less than conventional solar panels, making...
SunPower 110 Watt Flexible Solar Panel
This is a 110-Watt flexible solar panel from Sunpower that weighs a little over 4 pounds and has a 5.9 amperage capacity. Cost includes the junction box and MC4 connectors, and the panel has a 2-year product warranty and a 5-year power warranty.
Sunpower solar panels generally get very good reviews and are the solar panels our friend Brian (RV with Tito) has installed on his rig. And HE seems to be quite happy with them.
- Dimensions: 45.9"(L) x 21.9"(W) x 0.1"(H) (0.8" including J-Box)
- Weight: 4.4lbs - Lightweight, Portable, and Easy to Stow
Renogy 175-Watt 12-Volt Flexible Monocrystalline Solar Panel, 175W
This is another of Renogy’s well-reputed flexible solar panels, with a higher 175-Watt output. Reviews for these panels are excellent, and while a single 175W panel is sufficient for many campers, these panels can be joined in series or in parallel to create a larger solar array.
Weighing in at 6.2 pounds, this 175-Watt flexible solar panel carries Renogy’s industry-leading 5-year material and workmanship warranty and 25-year 80% output warranty.
- Extremely Flexible: This flexible panel is capable of meeting a wide range of applications where standard panels can be inconvenient to mount, such as...
- Ultra Lightweigh: Thanks to advanced polymer materials, this product weighs 70% less than conventional solar panels, making transportation and...
Are Flexible Solar Panels for RVs Worth It?
For certain applications, flexible solar panels are absolutely worth the investment. Their flexibility allows application on the many curved surfaces of a multitude of RVs including Class Bs with smaller roofs, teardrop campers and Airstreams with curved roofs, self-built vans, and yes – large Class A motorhomes like ours.
In weighing the pros and cons of flexible solar panels, we decided to give them a shot, and we’re unquestionably satisfied with our experience with our Xantrex Flex Max panels.
While they may not be right for every RVer or every application, flexible solar panels have filled a niche in the RV industry that travelers will appreciate for years to come.
Geek Out with Us Every Week
Join our newsletter to learn about all things RV-related. Every week we offer free tips, tricks, product reviews, and more to our online community of RVers. So, whether this is your first time on the road or you’re a seasoned expert, we’d love for you to geek out with us!