Everything you need to know about flexible solar panels
If you’re a boater, camper, or anybody who needs portable off-grid power, flexible solar panels are a great way to keep your devices powered with clean energy.
All of us are packing more and more energy-hungry devices with us all the time. Smartphones, tablets, cameras - indispensible little things that we need to keep charged all the time.
If you’re into outdoor activities or anything that takes you off the grid, keeping your devices charged starts to be a challenge if you’re away from a power outlet for a day or more.
If you only need a little power, portable batteries are good for a few charges of small devices. If you have bigger power needs and vehicle to carry it, you can even fire up a generator. But do you really want that kind of noise while you’re out in the woods, trying to enjoy a little quiet?
If you plan to be off the grid for days or even weeks, but don’t want the noise and maintenance issues of a generator, go with solar panels. Solar electricity is the ticket if you need a lot of power with little weight and zero noise.
The kind of solar panel we’re talking about is not the type you’d put on a house - too bulky, heavy, and not exactly portable. You want something lightweight. This is what flexible solar panels are for.
Types of flexible solar panels
There are two types of flexible solar panels that you’ll come across: thin film and crystalline silicon.
Thin-film solar panels
Thin-film is a type of solar cell where the photovoltaic material is essentially printed onto a surface. This is very different from the more common crystalline silicon solar cells that are used in most solar panels.
Flexibility is one of the main advantages of thin-film solar cells. Thin-film cells can be bent and even rolled. They can be placed on many different materials including glass, metal, and even fabrics. Because of this property, thin-film is sometimes used to make highly flexible, small solar panels for portable applications.
While thin-film solar has a lot of promise, crystalline silicon has a much larger global market, making it cheaper than thin-film. It also is less efficient than crystalline silicon, and many of the materials used, such as cadmium telluride or copper indium gallium selenide, are toxic.
Because of these disadvantages, thin-film isn’t very widely used. Still, this could change. For example, First Solar makes innovative thin-film based solar panels with high output. It’s also one of the larger US solar manufacturers.
Crystalline silicon solar panels
Most solar panels used today are made with silicon, which is the primary element in beach sand. The two types of solar cells on the market are polycrystalline and monocrystalline.
With both, the cells are made by cutting wafers of silicon out of a block. The cells are wired together, usually in groups of 60 or 72 cells, to make a panel.
The individual wafers are thick enough that they aren’t flexible. But it turns out that if you cut the wafers thin enough, they become fairly flexible while retaining their photovoltaic properties.
The result is a solar cell that can bend at about 30 degree angle. While this is less flexible than thin-film solar, it’s well suited for a lot of applications where you want the solar panel to conform to a curved surface, such as the roof of an RV.
Plus, these cells can be made of the same silicon as conventional panels, including high efficiency monocrystalline, gaining the benefit of economies of scale. For example, SunPower uses their Maxeon cells in both conventional rigid solar panels as well as their line of flexible panels.
Disadvantages of flexible solar panels
Given the benefits, you might wonder why all solar panels aren’t made to be flexible. Well, there are some tradeoffs.
Because of the thinner silicon, flexible solar cells are less durable over the long run. Also, instead of being protected by a thick layer of glass and a rigid alumimum frame, they are attached to flexible sheets subjecting them to more stress over their lifetime. Eventually, wiring can fail or cells can crack.
Because of this, flexible solar panels have shorter warranties. For example, conventional SunPower solar panels with Maxeon cells come with a 25 year warranty on both materials and power production, but a SunPower flexible panel (also with Maxeon cells) has only a 2 year materials and 5 year power warranty.
Best overall: Renogy 12 Volt Flexible Monocrystalline Solar Panel
Why we like it:
- Long warranty (25 year power, 5 year product)
- High efficiency (21%) monocrystalline
- ISO-9001 certification
- Reputable US-based company
Available in 50, 100, and 160 watt sizes.
Amazon rating: 4.3 stars$175 on Amazon (100 watt)
The Renogy series of flexible monocrystalline solar panels is your best overall value if you’re needing a well-made flexible solar panel. Constructed with 21% efficient monocrystalline silion, this panel will produce a lot of power with a relatively small footprint.
The Renogy panel comes with a remarkable 25 year power and 5 year product warranty, which is far longer than warranties offer by other companies, including SunPower.
At $175 for a 100 watt panel, this Renogy product is $24 less than the SunPower series.
Renogy is a US-based company that makes a wide variety of solar products.
Good deal: Rich Solar 12 Volt ETFE Flexible Monocrystalline Solar Panel
Why we like it:
- Long warranty (25 year power, 5 year product)
- High efficiency monocrystalline
- US-based company
Available in 80 and 100 watt sizes.
Amazon rating: 4.3 stars$140 on Amazon (100 watt)
If you’re shopping for a cheap flexible solar panel online, you’ll probably come across a lot of overseas brands that have minimal product specifications listed and perhaps even no warranty information.
That’s not the case with Rich Solar, which is a small company headquartered in Montclair, California. Their flexible solar panels use monocrystalline cells, have a great warranty, and seem to be well-constructed with an IP68 waterproof rating. Unlike those no-name overseas brands, with Rich Solar there are multiple support options by phone, email, chat, and social media.
These flexible solar panels come in 80 watt and 100 watt sizes and have a great price. The only reason they aren’t rated higher than the Renogy panels is because the documentation isn’t as good. For example, while it says this panel uses monocrystalline cells, the efficiency rating isn’t listed.
Note of caution: Rich Solar also makes a more expensive SunPower-based panel, but those are currently sold out. If you were reading about Rich Solar elsewhere and learned that they use SunPower, read the product description carefully before buying. The links for this item are for the product that uses generic monocrystalline.
Highest performance: SunPower Flexible Monocrystalline High Efficiency Solar Panel
Why we like it:
- High efficiency (23-25%) monocrystalline
- Good performance in high temperatures
- Decent warranty (5 year power, 2 year product)
- ISO9001 certification
- Reputable US-based company
Available in 50, 100, and 110 watt sizes.
Amazon rating: 4.5 stars$215 on Amazon (110 watt)
If you absolutely need maximum power performance from your photovoltaic system, then we recommend the SunPower series of flexible solar panels. These panels are made with Maxeon silicon, the same type used in their conventional solar panels. These monocrystalline cells are up to 25% efficiency, which are the best in the industry.
In addition, they have an excellent power temperature coefficient of -0.30 to -0.35% per one degree Celsius, which means that these panels will perform better than other panels when it’s hot. In comparison, the Renogy panel has a power temperature coefficiency of -0.42%, which means that the Renogy panel will lose more efficiency as the temperature increases. This matters if, for example, these panels are mounted on your RV and you’re driving around in the desert heat.
The SunPower panel comes with a 5 power and 2 year materials warranty. This isn’t nearly as good as Renogy’s, but better than other competitors.
SunPower is a very well known and established US-based company.
Other panels to consider
The panels below aren’t the best products in their category, but could be good choices for some people.
Winnewsun Bifacial 100 Watt Flexible Solar Panel
Why we like it:
- Unique bifacial design harvests sunlight from front and back of panel
- Smaller footprint than other flexible 100 Watt panels
- 5 year product warranty
What we don’t like:
- Taking full advantage of the bifacial cells requires special mounting
- Couldn’t find any information about the manufacturer
Available in 100 watts only.
Amazon rating: 4.4 stars$160 on Amazon (100 watt)
This flexible solar panel by Winnewsun is unique among all the panels listed on this page because it is a bifacial panel.
A bifacial solar panel has a transparent backsheet that allows the solar cells to capture sunlight from both the front and back of the panel. This makes the panel more efficient in terms of electricity generated per square inch because it can capture sunlight reflected from the ground, or whatever surface is behind the panel.
Don’t expect a doubling of efficiency: depending on how reflective the surface behind the panel is, you can expect an average power increase of 6-9%, although if you correctly install this above the bright white roof of an RV, you can probably expect to exceed a 9% gain.
The result is a smaller footprint solar panel. This panel 908 square inches in area, compared to 1,005 square inches for the Renogy panel.
Keep in mind that it doesn’t make sense it buy this panel if you intend to velcro or glue the panel to the roof of your RV. Instead, you want to use this panel with some type of tilted frame so that it can benefit from reflected sunlight that hits the back of the panel. One option could be to mount the panel to a sheet of plexiglas.
This product comes with a five year warranty, which is better than many other flexible solar panels.
One cautionary note: I couldn’t find any information the manufacturer, except for what is listed on their Amazon page. That said, the product manages a respectible 4.4 stars on Amazon.
ALLPOWERS 12V Flexible Solar Panel with SunPower cells
Why we like it:
- Uses high efficiency (23.5%) SunPower monocrystalline solar cells
- Cheaper than a SunPower solar panel
- 18 month product warranty
What we don’t like:
- Lower quality PTE plastic
Available in 50 or 100 watt sizes.
Amazon rating: 4.0 stars$180 on Amazon (100 watt)
This ALLPOWERS flexible solar panel is manufactured by a Chinese company and uses high efficiency SunPower solar cells.
It comes with fairly short 18 month product warranty, but at least that’s long enough to protect you from near-term product failures.
However, this panel uses cheaper PTE, which is a polyester that will degrade faster in sunlight than ETFE. This is one of reasons why this product based on SunPower cells is sells at a cheaper price.
It’s available in 50 and 100 watt sizes. If you want a high efficiency panel at a low price, this ALLPOWERS product could be right for you.
How to shop for flexible solar panels
If you want to do your own research on flexible solar panels, it can be a little tricky. Finding the best flexible solar panels for your application requires a more careful approach than buying regular panels. Here are some tips:
Tip 1: Check for industry certifications
When you buy a conventional solar panel in the United States, it will almost certainly have some industry quality and safety certifications listed on its product datasheet. These include UL certifications for fire, and manufacturing quality certifications such as IEC 61215 and ISO 9001. These certifications are required by many jurisdictions, such as the California Energy Commission, in order for a solar system to be allowed to connect to the grid or qualify for incentives.
Because flexible solar panels aren’t normally used for stationary applications such as houses, you will often find solar panels with lower quality standards.
Check the product datasheet before buying a flexible solar panel, and look for quality certifications such as ISO 9001 or IEC 61215. While certifications aren’t a product quality guarantee, they do indicate that a minimum manufacturing standard was met.
Tip 2: Check the warranty
A good warranty indicates that the manufacturer has confidence in the quality of their product. Our recommended models here have the best warranties we could find in flexible solar panels.
Tip 3: ETFE is better than PET
Flexible solar panels are constructed by sandwiching the solar cells between layers of a polymer. Cheaper panels will use a polymer called polyethylene terephthalate, while better panels will use ETFE (ethylene tetrafluoroethylene). ETFE has slightly better light transmittance compared to PET, and is also more durable, which is an important consideration when your panel is exposed to the heat and rain on top of your RV’s roof.
Tip 4: Watch out for manufacturers advertising SunPower
SunPower is a well-known US-based manufacturer known for making high-quality, high-efficiency solar cells. SunPower makes flexible panels based on their Maxeon line of solar cells, but they also sell Maxeon cells to third-party manufacturers.
You’ll often find that these manufacturers advertise that they use SunPower cells, but also somehow offer their panels for less than SunPower. How is this possible?
Most likely, that money savings is the result of sacrificing quality, which is something you can estimate by using our tips above.
For example, on Amazon you can find a company called Giaride (I’ve never heard of them either) selling a flexible 100 watt solar panel for about $60 less than SunPower.
But if you examine Giaride’s product specifications for that panel, you’ll see that there are no quality standards listed, and their product warranty is only 18 months, while SunPower offers a 2 year product/5 year power warranty.
Is that possible tradeoff in quality worth saving $60? Think of the hassle of being in the middle of a week-long camping trip and having your solar panel system suddenly conk out. Would it have been better to spend a little more money on a better from a reputable manufacturer? We think so.
Maintenance tips for flexible solar panels
Flexible solar panels are a great product for certain applications, but the tradeoff is poor durability and a generally shorter lifespan. To maximize the life of your product, follow these tips:
- Store them when not in use because UV light and exposure to the elements will degrade your panels over time. If you’re mounting these on a vehicle, consider using velcro to secure them to the roof so that you can easily remove and store them when not needed.
- Even though they’re bendable, avoid bending them as much as possible. These solar panels are flexible within limits, but they will eventually crack if stressed too far. To minimize the risk of damage, handle them carefully and flex them only as much as needed to fit the surface that you’re installing them onto.
- Store them gently. For similar reasons, you want to store these panels gently. Keep them flat and don’t stack anything on top of them.
- Clean them periodically. The maximize power performance, keep these panels clean. Be sure to remove any bird droppings that land on them, which can have a corrosive effect on the plastic. Clean them gently with plain water to avoid scratching the surface.
To learn more, read our complete guide to solar panels for RVs.