The things that go into making a solar panel are vital for its performance and efficiency. One of the crucial components of a solar panel is the material used for coating the surface.
ETFE is the most commonly used coating material for flexible solar panels. Being a highly flexible material, its mechanical attributes come in handy in these solar panels. Besides its pliant nature, ETFE is thin, lightweight, and visually appealing, making it a perfect fit in flexible solar panels.
Previously, solar panels used to come with PET coating. Though more expensive, ETFE coating is a big leap in technology and a marked improvement in all aspects in comparison with its predecessor.
ETFE solar panels come with a non-adhesive finish. Dust, dirt, and debris have less tendency to remain on the panel surface, with most of it getting washed away in rain. This means less effort in maintenance.
Hassle-free ETFE solar panels are available in flexible, partially flexible, and even foldable designs. The ease of use and simple installation make these panels suitable for a variety of applications, unlike the more rigid conventional solar panels.
This article explores the topic of ETFE solar panels and has compiled all information about it for easy reference. Here, you will find all your questions about these solar panels answered in detail and with clarity.
What does ETFE mean?
Ethylene Tetrafluoroethylene or ETFE is a fluorine-based plastic polymer similar to the more popular Teflon. It is made from polymer resin and extruded into a thin film. Its high solar transmittance makes it ideal as a protective coating material for solar panels.
ETFE is now commonly used for coating the front and back panels of flexible solar panels. Its superior light transmission, resistance to fire, and non-adhesive properties have helped in its popularity.
One of the most vital elements of ETFE is ethane. An ethane molecule is highly stable with the ability to withstand high temperatures and chemical reactions.
The chlorine atoms present in the ETFE polymer help in preventing discoloration of solar panels, even after prolonged exposure to ultraviolet radiations.
As ETFE is completely UV-permeable, more solar energy falls on the solar cells, leading to more power generation.
These properties of the ETFE coating result in added efficiency for these flexible solar panels.
What is the relevance of ETFE in flexible solar panels?
The primary function of ETFE coating is to protect the components of the solar panel including the solar cell from:
- Extreme weather conditions
- Dust, dirt, debris
- Physical force and stress
- Extreme temperature variations
- UV radiation
Moreover, solar panels with ETFE fabric lamination get extra protection from electric conduction between solar cells and the environment. ETFE acts as an insulating layer in flexible solar panels. This is essential for solar panels used in outdoor settings.
Though the primary role of ETFE in solar panels is boosting energy generation, its application goes much beyond this. All these additional benefits don’t come at an extra cost to the environment either.
ETFE is a polymer that is both sustainable and recyclable. It’s compact and lightweight, translating into a lower carbon footprint for solar panels, especially during transportation.
ETFE is a big leap forward from PET coating for solar panels. Until something better is developed, ETFE remains the best choice in coating material for solar panels.
Components of the ETFE solar panels
ETFE film: This is a thin film of protective coating installed on a solar panel. Earlier solar panels used to be coated with more rigid PET material.
Ethyl Vinyl Acetate (EVA): This is used to encase the solar panels, offering them additional physical support and protection from environmental variations. The advantage of EVA is that it allows sunlight but prevents the degradation of panels.
Heat-resistant rubber strip: This offers protection for the solar panels’ edges from breakage and delamination. As the panels are kept outdoors, the ability to withstand temperature variations is vital.
Backer board: Typically made from aluminum or fiberglass, the primary function of the backer board is to afford solar panels flexibility. Though aluminum is more commonly used as it is cost-effective, fiberglass is the better choice.
Photovoltaic connectors: Most solar panels have MC4 connectors for interconnectivity. Some solar panels available in the market don’t provide connectors as part of the package. You have to purchase them separately.
Photovoltaic grommets: These are eyelets placed in the holes cut into the corner of solar panels. Most panels come with 4 grommets for easy mounting.
Photovoltaic cells: Last but not least among the ETFE solar panel components are solar cells. These PV cells may be monocrystalline silicon, polycrystalline silicon, or thin film.
A comparison of ETFE solar panels with non-ETFE solar panels
This table offers you a comparative analysis of various features of ETFE and non-ETFE solar panels.
|Features||ETFE PV Panel||Non-ETFE PV panel|
|Performance in dim light||Flexibility makes it easier to capture maximum sunlight||Lower performance due to its more rigid nature|
|Efficiency||Medium efficiency||Higher efficiency|
|Durability||Highly durable due to the tough nature of the coating||Average durability. May develop microcracks|
|Life expectancy||5-15 years||20-30 years|
|Weight||4-10 lbs||15-50 lbs|
|Application||Very versatile due to its flexibility||Can be installed only on flat surfaces|
|Maintenance||Less maintenance and is easy to clean as it is non-adhesive||Needs to be cleaned more frequently|
Note: Both ETFE and non-ETFE solar panels have their own advantages and disadvantages and hence have distinct applications. If you want a solar panel for a specific purpose, one may be better than the other.
ETFE solar panels are better suited for outdoor applications and on curved surfaces. Since they are thin and lightweight, ETFE solar panels are ideal as portable energy sources.
However, conventional solar panels are preferred for rooftop and ground-level solar installations because they need not be moved and have higher efficiency levels.
How does an ETFE flexible solar panel compare with a PET panel?
Before the invention of ETFE coating in the 1970s, solar panels used to have PET coating. Polyethylene Terephthalate or PET is transparent, rigid, sturdy, and durable plastic. Though PET coating comes with many advantages, ETFE coating is better suited for solar panels on many counts. Because of its superior features, ETFE is fast replacing PET as the coating material for solar panels.
Here is a comparative analysis of ETFE and PET coating for solar panels.
|Features||ETFE coating||PET coating|
|Durability||More durable||Less durable|
|Temperature tolerance||Can function in a wide range of temperatures||Deteriorates in extreme temperatures|
|Resistance to dust and corrosion||Better resistance to deterioration||Average resistance to wear and tear|
|Heat resistance||Can withstand high heat for long durations||Can tolerate high heat for a shorter duration|
|Chemical resistance||High resistance to chemical reaction||Less resistance to chemical reaction|
|Reflect/absorb sunlight||No reflection. Absorbs sunlight completely||Reflects some sunlight, bringing down efficiency|
|Appearance||Aesthetically appealing||Average looking|
|Fit for marine application||High resistance to saltwater corrosion. Ideal for marine use||Gets easily corroded by alkali and acid. Not good for marine use|
|Cost factor||More expensive||More affordable|
Note: In every way, ETFE coating is superior to PET coating, except that it is more expensive. For this same reason, ETFE coating has taken over the solar scene by storm, almost wiping out the use of PET coating.
How durable are the ETFE solar panels?
Solar panels coated with ETFE can withstand extreme weather conditions such as high wind, hail, and snow besides stresses induced by other physical factors.
Unlike its predecessor PET modules, ETFE solar panels don’t develop fissures and cracks as easily or often. In fact, ETFE solar panels can bear the weight of a person without damaging the solar cells or the connectors within.
Due to their durability and ability to withstand extreme conditions, ETFE solar panels are used in portable solar chargers meant for outdoor activities like hiking and camping.
Besides their high levels of physical endurance, ETFE solar panels also display high resistance to dirt and dust. They continue to be equally efficient in extreme temperatures.
Let’s check out these properties in more detail.
As the ETFE coating ensures a non-adhesive surface for the solar panels, dust and dirt don’t easily stick to the surface.
Dust and dirt can form a layer on the surface of solar panels and reduce their ability to absorb sunlight, thus, reducing their efficiency. ETFE coating helps solar panels avoid this inherent problem in solar panels. This ensures that solar panels function with utmost efficiency.
As solar panels are kept outdoors, they are exposed to environmental elements including moisture, bird droppings, and pollutants. As ETFE has high resistance to chemical reactions, it protects the solar cells inside from damage and deterioration.
High cold/heat resistance
The ETFE coating material can function in the temperature range of -40℉ to 302℉. This means ETFE solar panels can function efficiently anywhere from Fairbanks, Alaska to Death Valley, California.
What is the temperature at which ETFE solar panels function the best?
Being a device working on solar energy, the efficiency of solar panels goes up as the temperature rises. However, for ETFE solar panels, the peak efficiency is when the temperature is 77℉.
Together with a wide spectrum of favorable characteristics, ETFE is the best coating material invented so far. It is its presence that makes flexible solar panels an attractive proposition. The same positive traits of ETFE polymer are immensely helpful in other industries as well like mechanical and chemical industries.
Flexible, semi-flexible, or foldable – Which makes the best use of ETFE coating?
A solar panel that can be bent is considered flexible. An ETFE flexible solar panel doesn’t come with an aluminum frame or protective glass cover. All the features in a standard solar panel that adds to its rigidity are not present in ETFE flexible solar panels.
Semi-flexible, as the name indicates, can be bent better than rigid solar panels but not as much as flexible solar panels. They lie somewhere in the middle of both. Typically, semi-flexible solar panels can be bent to an angle between 10°-30°, not more and not less. If forcibly bent more, these solar panels will break.
Solar panels can be folded when their flexibility is very high. Like a piece of cloth, you can fold them up, place them in a bag, and carry them around. Foldable solar panels find their application as wraps and drapes. They can be swathed around light poles to capture sunlight and generate electricity.
Specification of an ETFE flexible solar panel
As the basic physical properties of ETFE solar panels vary vastly from the standard rigid panels, it is important to have a better idea of their physical description as well as capacity and performance.
Size of the panel
Being thinner and more compact than standard rigid solar panels, ETFE solar panels are smaller in size. When it comes to thickness, it averages about 0.1”. However, you will find ETFE solar panels as thin as 0.04” or even thinner. A quick search for product specifications will give you exact figures.
This figure represents the amount of power the solar panels are capable of generating. As the wattage of the solar panel goes up, the more power it can produce.
For the convenience of users, solar panels are available in the market in a wide range of wattages. The most commonly available wattages are 2W, 5W, 18W, 20W, 55W, 75W, 100W, 150W, 200W, and so on.
Voltage is the potential difference of a system, in this case, the solar panel. The common voltage rating for ETFE solar panels is 12V, 24V, 36V, 48V, and so on.
Compared to standard solar panels, ETFE solar panels are much lighter. While regular solar panels weigh around 40-50 lbs, the average weight of ETFE solar panels is 5 lbs. Those who are used to handling standard solar panels will find ETFE solar panels unbelievably lightweight.
Just to help you understand the specifications of ETFE solar panels, here are a few examples.
1. Topsolar Flexible Monocrystalline Solar Panel 100W 12V
Dimension: 20.47 x 42.71 x 0.1 in (520 x 1085 x 2.5mm)
Weight: 3.97 lbs (1.8 kg)
2. Renogy 100 Watt 12 Volt Flexible Monocrystalline Solar Panel
Dimension: 48.0 x 21.6 x 0.08 in (1219 x 546 x 2 mm)
Weight: 4.2 lbs (1.9 kg)
3. SunPower 110 Watt 18.8 Volt Flexible Solar Panel
Dimension: 45.9 x 21.9 x 0.1 in (1166 x 556 x 2.5 mm)
Weight: 4.4 lbs (2.0 kg)
How much do the ETFE solar panels cost?
Two main factors influence the cost of ETFE solar panels. They are:
- Power rating
- Backer board
To help you understand this, here are a few examples.
- One of the most popular power ratings for an ETFE solar panel is 12V 100W. This is typically priced around $200.
- Among portable ETFE solar panels, 12V 20W is in high demand. With an aluminum backer board, the cost is around $60-$70.
- An 18V 50W ETFE module with a fiberglass backer board is typically priced in the range of $135-$150.
- A flexible 300W monocrystalline PV module costs around $450.
Is the ETFE solar panel an affordable choice?
Price-wise, ETFE solar panels cost more than PET solar panels and standard rigid panels. However, its superior features make them worth the extra money spent. Less effort and lower maintenance costs are definite attractions of ETFE solar panels.
Where to shop for ETFE solar panels?
Direct purchase from manufacturers is always recommended to ensure authentic products and lower margins. Here is a list of the top manufacturers of ETFE solar panels.
Renogy, WindyNation, Tesla, Sunpower, Lensun, LG, AllPowers, RichSolar, Chanve, Giaride, GC, Sunbeam, Kingsolar, LinkSolar, Solbian, and Gioco.
Buying directly from the manufacturers need not mean you need to buy from their brick-and-mortar stores. Most brands have online stores, where you can place your order. International shipments are also offered by some European manufacturers.
Buying tips for ETFE solar panels
It’s important to know what to look for when shopping for solar panels. Otherwise, all of them will look the same and seem similar.
Buying reputed brands is highly recommended to ensure quality and longevity. You may find cheaper options online from unknown brands, but these may be of inferior quality and may stop working a few months after installation. The money you think you saved will actually be a total waste.
Get an idea about the space available to keep the solar panels. This is the starting point when shopping for flexible solar panels because this is something you cannot change and need to work with. Based on this, you need to figure out the power rating, size, and the number of panels you should buy.
Assess your energy demand to know the type of ETFE solar panels to buy. In case you are searching for a power source for your outdoor activities, list the gadgets you often carry around and the vehicle you use to travel around. From this information, you can calculate your power need and figure out the solar panel needed to meet this demand.
A guide to installing ETFE flexible solar panels
Before we go ahead with the installation process, let’s see what comes in an ETFE solar panel kit.
These are the basic components of an ETFE solar panel kit.
- ETFE flexible solar panels
- MC4 connectors
- Circuit breaker
- MPPT charge controller
- Cables and cable glands
For a 300W (3 x 100W) flexible solar panel kit with these components, you may have to shell out anything between $1500 and $2000.
If you are planning to install solar panels by yourself, you should ensure the availability of these materials and tools.
- Basic electrical tools like a screwdriver, wire stripper, drill, and measuring tape
- Adhesive tape or glue for direct mounting
- Brackets for rack mounting
Note: While choosing accessories for solar panels, you need to ensure that they are waterproof or at least water resistant. They should also be able to withstand the variations in temperature outdoors and weather changes.
The process of installation
Although you can glue the ETFE solar panels to the surface, it is ideal to use a rack mounting system as this creates space between the panels and the surface, thus avoiding overheating issues. Overheating is one of the main reasons for the panel’s reduced efficiency levels and damage.
However, in some instances, rack mount should be avoided and direct mount chosen. As in the case of streamlined surfaces like that of the roof of an Airstream. Placing a rack mount in such cases may lead to air turbulence and resultant issues.
Before choosing the rack mounting system, you should have a clear idea about the layout of the area where you are planning to install the solar panels.
If it is a temporary setup, you can just place the rack on a flat piece of ground and keep the panels on it. This is the simplest way you can install solar panels while camping.
However, if you want a permanent installation, as in the case of a golf buggy, you need to secure the racking mount to the surface. Follow these steps to fix a rack mount.
- Clear the surface and clean it thoroughly with a clean cloth. You can rub alcohol on the surface to remove dust and dirt.
- Secure the rack mount on the surface using drills, brackets, and screws. As an alternative to metal racks, you can consider PVC pipes.
- Fix the solar panels on the rack using grommets.
- Use MC4 connectors to link the panels together and then to the charge controller.
- When the solar panels are exposed to sunlight, the system will begin to generate electricity. Plug in your device to enjoy the free energy.
If you want more information on how to charge a golf cart with solar panels, read this article.
Tip: If you prefer the outdoors, you will find it handy to have spare portable ETFE flexible solar panels that you can deploy anytime you want extra energy. These can act as add-ons to your fixed solar panels.
ETFE solar panels: Applications
At its best, the ETFE solar panels offer a 15-25% efficiency level. Efficiency-wise, this is excellent in comparison with standard rigid solar panels. In addition to this, ETFE solar panels come with a wide range of superior features as well.
If you are unsure about choosing between conventional solar panels and ETFE solar panels, try answering these questions.
- Is it beneficial to have lightweight solar panels?
- Are you looking for a portable power source?
- Are you planning to install the panels on a rounded or complicated surface?
- Are you searching for a power source for your outdoor projects?
If the answer to any of these questions is “Yes”, there is no need for you to feel confused anymore. Go right ahead and purchase ETFE solar panels.
The most common applications of ETFE solar panels are on golf carts, RVs, caravans, camper boats, Airstreams, camp trailers, and tub trailers. As the roofs of most of these are curved and not-flat, conventional panels are unsuitable. ETFE solar panels are a perfect fit in these situations.
When ETFE solar panels are installed perfectly, they will not hinder the aerodynamics of the vehicle or create resistance to airflow. Besides providing power to run these vehicles, ETFE solar panels will have power left over for charging small devices like smartphones, tablets, and cameras.
What to do when the ETFE solar panels peel off?
The ETFE coating on the panel surface is usually strong and stays put for years. However, when the panels get older or in extremely adverse conditions, this coating can peel off.
During your routine inspection of panels, if you notice the coating peeling off in one of the panels, should you attend to it immediately? Or leave it as such? Can this be repaired? Is scraping it off a good idea?
It is natural to have such questions. And you need to know the answers to them to do the right thing.
Leaving a peeled-off panel unattended may lead to shorting and overheating. This will ultimately result in reduced current production and voltage.
That doesn’t mean you should scrap the half-peeled coating off the panel. If you do this, the panel will lose the advantage. Instead, you should get it repaired.
Peeling ETFE solar panels can be repaired by trimming the connections in the damaged panel and adding a clear epoxy layer as a temporary measure. This will be enough to take care of the efficiency-related issues.
Note: The peeled ETFE solar panels may never reach their peak efficiency even after repair. But this is the best that can be done about them.
You can reduce the chance of damage by handling the panels with extra care.
Advantages of ETFE solar panels
Solar panels are exposed to maximum sunlight and this can lead to the panels heating up. Especially in thin panels, this may result in overheating.
Fortunately, ETFE solar panels are well-equipped to handle the heat. They can tolerate high temperatures and wild fluctuations in temperature without getting damaged or any reduction in efficiency levels.
ETFE solar panels are super thin and compact, making them the perfect solution when space is a constraint. Also, since these are flexible solar panels, they can be installed on complex and unconventional surfaces.
ETFE solar panels come with an efficiency in the range of 15-25%. This is almost as good as the efficiency offered by standard solar panels.
High solar permeability
The ETFE coating has chlorine atoms present in it, ensuring no discoloration and offering protection for lamination. This helps in raising the light transmittance, thereby increasing energy production.
The non-adhesive nature of ETFE coating ensures that dust and dirt don’t stick to the panel surface. This means they need not be cleaned as often as conventional panels.
Sturdy and long-lasting
ETFE coating adds strength to the solar panels, making them robust and durable. The tough ETFE coating protects the solar panel components inside. As solar panels are kept in the open and exposed to harsh weather conditions, their ability to withstand such conditions is vital for their performance and longevity.
Disadvantages of ETFE solar panels
ETFE solar panels are better in every way, except for their price in comparison with conventional panels. They are priced 2-3 times more than aluminum-framed rigid panels.
To get the best out of them, buy quality panels from reputed manufacturers.
If bent beyond the limit, ETFE solar panels may develop cracks or even break. However, if usage instructions are followed properly, they are sturdy and durable. For this reason, it is vital to know the maximum flexible limit to avoid damage.
Overheating and discoloration
When exposed to high heat, ETFE solar panels can end up with discoloration or overheating. Discoloration or yellowing happens because of UV exposure. This can reduce the efficiency of the panels, thereby the power it generates.
Frequently asked questions
There are more efficient rigid solar panels than ETFE solar panels but the efficiency of ETFE panels is definitely above average. Taken together with their array of other benefits, ETFE solar panels are, no doubt, worth buying.
The price tag is one of the main setbacks for ETFE solar panels. PET-coated panels are much cheaper. If you are looking for a reliable power source for your outdoor activities, look no further. ETFE solar panels are a good investment.
ETFE solar panels come with varying levels of flexibility - semi-flexible, flexible, and foldable. Instead of glass backer boards in conventional panels, ETFE solar panels have aluminum or fiberglass boards.
A point to remember is that not all flexible solar panels come with ETFE coating. Some still use PET coating.
These ETFE solar panels are made with an adhesive strip on the back. Installing them is very easy; all you need to do is peel off the protective layer and stick them to the surface. There is no need for an elaborate racking system to fix the solar panels or the need to apply glue. It’s all there, ready-made for you.
Flexible stick-on solar panels are the most versatile. You can use them on surfaces of any shape, even uneven ones.
The most prominent feature is their compactness and wafer-like thickness. It can either be black or blue depending on the solar cells in it. Monocrystalline silicon cells are black and polycrystalline cells are blue. They are aesthetically appealing.
Though these panels are thin, they are sturdy and don’t get damaged easily. For longer periods, ETFE solar panels can bear a weight of approximately 25 lbs. Even if you walk on them, they won’t break or develop cracks. However, for the sake of maximizing energy generation, you should not keep anything on top of them.
As they are very thin, there is a high probability of these flexible solar panels overheating when exposed to high temperatures. You can avoid this by using a racking system that will keep the panels off the surface, providing enough ventilation below.
If you stick the panels to the surface, there is always a higher chance of overheating and a resultant reduction in efficiency levels.
Although the ETFE coating is non-adhesive and doesn't allow dust and dirt to stick to it, the flexible solar panels need to be cleaned occasionally. However, the frequency is much less when compared with conventional solar panels.
If you live in a place with frequent rains, that itself should be sufficient to keep the panels clean. If you use these panels only rarely and keep them stored at other times, before deploying them, it is ideal to wipe them down.
The average life of these solar panels is 5-15 years. This is short compared to conventional panels, especially considering the higher price tag.
However, ETFE solar panels are typically used for shorter durations in various means of transport such as RVs and camper boats. When the lifespan of such a vehicle is less than 15 years, these solar panels would have served their purpose by then.
We cannot do without a myriad of gadgets even when we go hiking or camping. When there is no power source available 24×7, it can be hard to keep them going. This is when a solar power system comes in handy.
Installing the ETFE flexible solar panels is the ideal way to keep all your devices charged around the clock. When you are on the go, ETFE solar panels are the best bet because of their horde of useful features. Not only are they thin, compact, and lightweight, they are flexible enough to be installed on any surface.
ETFE solar panels are useful not just while traveling. They are perfect for use on golf carts or other outdoor activities. This is also an excellent choice as a backup power source in the event of grid failure.
As long as the sun is shining, with ETFE solar panels, you are assured of power.
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