How Efficient Are Flexible Solar Panels?


Flexible solar panels are easy to fold, to fit over curved surfaces, and to install. On the surface, they seem like a great choice for any renewable-energy installation. But by going flexible, are you sacrificing efficiency for convenience?

flexible solar panels

Flexible solar panels are not very efficient. You need more of them to produce the same amount of energy as more standard panels. However, their portability nonetheless makes them a good charging option for when you’re on-the-go.

Below, we compare and contrast the different types of solar panels. We also discuss the pros and cons of flexible solar panels, which have much to offer under the right circumstances.

What Are the Different Types of Solar Panels?

All solar panels are composed of solar cells that are photovoltaic, which refers to the electric current that’s generated when light touches two substances. These solar cells take the sun’s energy as it manifests in photons and converts it to electricity.

One standard solar panel usually has 96, 72, or 60 solar cells. Standard solar panels also have a frame made of metal that surrounds the cells.

That’s the basic outline. However, all solar panels are not the same and can vary in their construction and materials. There are three primary types:

Monocrystalline

The solar cells in a monocrystalline solar panel are sliced from one pure crystal of silicon. (Hence the prefix “mono,” meaning “one.”) They’re cut into wafers that are then arranged in columns and rows, placed beneath a glass sheet, and framed with metal. 

You can recognize a monocrystalline solar panel by the shape of its solar cells: The cells have rounded edges thanks to the cylindrical crystal from which they were cut.

Polycrystalline

Although polycrystalline solar cells also come from silicon crystals, they are not cut from one single crystal. Instead, they’re made of many different crystal fragments. (Hence their prefix, “poly.”) Sometimes, these fragments are what have been leftover from the production of monocrystalline cells.

Only after these fragments are melted and shaped into blocks are they cut into wafers. Because they are cut from a block of melted fragments rather than from a curved silicon crystal, polycrystalline wafers have more rectangular edges. 

Thin-Film

Lastly, thin-film solar panels differ from both mono and polycrystalline panels. Their solar cells are made from many different kinds of materials. 

Three of the more common thin-film materials are:

CIGS

“Copper Gallium Indium Diselenide” is the compound from which one type of thin-film solar cell is made. A conductive layer — which could be plastic, steel, glass, or aluminum — is placed both on top of and beneath the CIGS cells. Electrodes on both sides catch currents of electricity. 

CdTe

The use of Cadmium Telluride or CdTe solar cells is more widespread than the other options. Here, the conducting layers placed both above and below the CdTe solar cells are transparent, helping to catch the light. In order to help protect the panel, an additional layer of glass is set on top.

a-Si

As the name suggests, amorphous silicon panels have the most in common with monocrystalline and polycrystalline panels. Just like the cells in those panels, a-Si solar cells use silicon. However, a-Si wafers are not made of crystalline silicon. They are instead composed of non-crystalline silicon that is set atop metal, glass, or plastic.

What Are Flexible Solar Panels?

Most flexible solar panels currently available on the market are part of this last major category: Thin-film panels. 

History

Thin-film solar panels have been around for over three decades. One of their first uses was powering solar calculators. These calculators included small quantities of a-Si or amorphous silicon.

Just before the turn of the 21st century, an Indian American scientist named Subhendu Guha, who had also previously worked with a-Si, helped invent flexible solar shingles.

Guha’s flexible solar shingles were installed directly on the roof of a house in place of typical asphalt shingles, where they absorbed the sunlight before converting it to electricity that powered the home.

Today, thin-film panels can be found in even grander schemes, from solar-powered farms to electric cars.

How Do They Work?

The thinness of these wafers makes the panels themselves more flexible than either monocrystalline or polycrystalline panels. In fact, the layers in thin-film panels can be 300+ times smaller than the layers in customary panels that have silicon solar cells.

This is quite something when you consider that the average wafer in mono or polycrystalline solar cell has a thickness of roughly 200 micrometers (.0002 meters). That’s only a little bit thicker than one of the hairs on your head.

Flexible solar panels work much as other panels do: although their materials are different, they still catch the sunlight and convert it to electricity. They have the same dark — black or blue — coloring that’s optimized to absorb as much light as possible while the sun is out.

However, more traditional mono and poly solar panels tend to be bigger in both physical size and wattage. A typical (more rigid) solar-panel system that supplies the power for a house, for example, might have heftier panels that boast 340 watts of power each. 

On the other hand, flexible solar panels tend to be lower wattage — generally 50-300 watts — while also being smaller.

Efficiency Comparison Between Solar Panels

Now that you know a little more about each type of panel and its composition, the question is: how do these differences in materials and production affect each solar panel’s efficiency?

Let’s start by comparing the more standard types of panels, monocrystalline, and polycrystalline.

Between Mono & Polycrystalline

We know that monocrystalline wafers are cut from a single pure crystal of silicon. This is why they are of higher quality than polycrystalline wafers, which are sliced from a block of silicon crystal fragments that have been melted together. The higher quality of monocrystalline solar cells translates to greater efficiency.

On average, monocrystalline solar panels have an efficiency of around 20﹪. The efficiency of many polycrystalline solar panels, in contrast, is around 16 or 17﹪.

What polycrystalline solar panels can boast of is a more consumer-friendly price tag. Their production process — melting together crystalline fragments of silicon — is cheaper than the process of producing monocrystalline solar cells. This makes poly panels more inexpensive.

However, polycrystalline panels take up more space. You will need more poly solar panels to generate the same amount of energy as fewer mono panels. This also makes poly panels less efficient than their mono brethren.

The issue of space is something we’ll see again with flexible solar panels as well.

Between Mono, Poly, & Flexible Solar Panels

Depending on the type you purchase, flexible solar panels can have an efficiency of roughly 7-13﹪. That’s several percentage points lower than poly panels and could be as much as half (or more) that of monocrystalline panels.

Because their efficiency is so much lower, you will need more of them to generate comparable energy — even more of them than polycrystalline panels.

This point is especially important when it comes to rooftop installation. Your roof may simply not be large enough to accommodate all the flexible solar panels that would be needed to power your home. 

Additionally, the size of flexible solar panels matters a great deal. Mono and polycrystalline solar panels usually come in one of three standard forms: they’ll have 96, 72, or 60 solar cells, as mentioned above.

But thin-film solar panels are not necessarily available in identical sizes. How much power a thin-film panel can generate will depend largely on how big it is, physically.

In general, it’s monocrystalline and polycrystalline solar panels that will generate more power per square footage (or per square meter).

What Is the Most and Least Efficient Type of Solar Panel?

The most efficient type of solar panel is the monocrystalline panel. Its solar cells are of the highest quality, and you need fewer panels to generate the same amount of energy. 

Currently, the least efficient type of solar panel is the flexible solar panel made from thin-film technology. You need many more flexible solar panels to generate comparable energy.

What Are the Advantages and Disadvantages of Flexible Solar Panels?

That being said, it’s important to remember that efficiency is not the lone criterion to consider when it comes to solar panels in general and flexible solar panels in particular. 

There are several benefits that flexible panels offer:

  • Lightweight. Because they are thin, flexible solar panels are not as heavy as comparatively bulkier mono and polycrystalline panels. 

Although space is a significant issue when it comes to rooftop installation, flexible solar panels can still be a good choice for smaller roofs or roofs that can’t bear the weight of mono and poly solar panels. That’s where lightweight, flexible solar panels could come in handy.

  • Portable. The panels’ lighter weight also makes it easy to cart around. Additionally, you can fold and store them without difficulty because they are so flexible. For on-the-go charging needs, flexible solar panels are worth considering. 
  • Inexpensive. Flexible solar panels are among the most affordable panels available. For one thing, you don’t need as much material to make them, which means they’re cheaper to make, and consequently less expensive for you to buy. Consider that you can currently purchase a flexible solar panel with 100 watts of power for $100.
  • Easy Installation. For another thing, the panels’ lightness and portability make them relatively easy to install as well. If you aren’t planning on doing the work yourself, you could potentially cut down on labor and installation costs by choosing flexible panels.
  • Versatile. These panels’ flexibility means they’re well suited for curved or oddly shaped structures. They can be manipulated to fit different surfaces, making them a worthy option for unconventional or atypical installations. 

It’s interesting to note that while many consider it a disadvantage that flexible solar panels take up so much space, this is not always an issue. Many of the globe’s biggest solar-powered farms utilize thin-film cells.

However, there are also a few other disadvantages to keep in mind:

  • Less durable. The same thinness that makes flexible solar panels so light and flexible also renders them less hardy, particularly as the years go on. Some lack a layer of glass on top and are not framed with metal (which would inhibit their flexibility). Over time, flexible panels are subject to more strain since they are affixed to supple sheets. Wiring issues can occur, and the solar cells can break.
  • Shorter warranties. What this means is that flexible solar panels tend to have shorter lifespans than mono or polycrystalline panels. You will see this fact reflected in the shorter warranties (around 2-5 years) that manufacturers may include for both the panels’ materials and power.

What Are Flexible Solar Panels Best Suited For?

When it comes to home rooftop installations, either mono or polycrystalline panels will likely be your best bet. If you have the budget, it may be worth spending the extra money on monocrystalline panels so you can benefit from their efficiency. Polycrystalline panels cost less but keep in mind that you will need more of them.

While flexible solar panels may not be the most efficient choice for your home’s rooftop, they are still a great option for any of the following:

  • Boating. Their portability makes flexible solar panels ideal for many outdoor activities. Instead of a generator that makes a lot of noise, try powering your boat with solar energy. The panels can be used for smaller fishing boats as well as yachts. There are even flexible solar panels made, especially for marine ventures.
  • Camping. Flexible solar panels also make for excellent power banks for your tent. They’re easy to fold and pack and then to store away when you don’t need them. Retailers will often list them as camping panels.
  • RV-ing. Flexible panels are good options for portable solar-power systems in general, and installing them on RVs is one popular example. The installation is simple, cost-effective, and of course, eco-friendly.
  • On-the-go charging. Even if you don’t own an RV, you could still install a flexible panel system on the roof of your car. It won’t power the vehicle, but you could use it to charge your phone or other electronics whenever and wherever you might be traveling.
  • Commercial roofing. Very big rooftops on commercial structures sometimes cannot support the weight of more standard mono and polycrystalline solar panels. These are the sorts of roofs for which lightweight, flexible solar panels are often well-suited.

What Should I Look for in a Flexible Solar Panel?

If you do decide that flexible solar panels are what you’re looking for, you will want to keep several things in mind while shopping for the right ones.

  • Wattage. The amount of power that a flexible solar panel can generate will be stated in wattage on the packaging. The higher the wattage, the more devices the solar panel can charge, and/or the more powerful the vehicle it can power. 

If you’re looking for a panel to charge your boat for a few hours, for example, a flexible solar panel with 100 watts should generally do the trick. On the other hand, something like an RV might require a higher wattage of around 300. Just remember that panels with higher wattages are also more expensive.

  • Weight. You will usually find that flexible solar panels fall within a short-range when it comes to weight: between 4 and 8lbs. (1.81-3.62kg). 
  • Angle. Not every flexible solar panel will bend at the same angle. However, 30° is fairly standard.
  • Warranty. Generally speaking, a longer warranty indicates a quality, durable product. But since flexible solar panels are not as long-lasting as their mono and polycrystalline solar panel counterparts, you’ll find that their warranties are shorter: often in the range of 2-5 years (although that can vary, depending on the product). Some warranty, however, of at least a few years should be included.
  • Installation guide. It is typically a good sign if a manufacturer has included an installation guide along with the panels. There’s some debate as to whether an installation guide is even necessary for flexible solar panels since the panels can be so simple to install — in the case of some RV installations, you can just use Velcro! 

But a thorough manual indicates the company cares that you install their panels correctly. This is a sign that the company cares about its products, which usually means the products are of higher quality.

  • Certifications. Your flexible solar panels should come with industry certifications that prove the panels have met a baseline standard for quality. Look for ISO 9001 or the certification IEC 61215.
  • Polymers. You will also want to keep an eye out for the types of polymers used in your flexible solar panels. 

A polymer layer is placed both on top of and beneath the solar cells in a flexible panel. The polymer PET (Polyethylene Terephthalate) is used in lower-quality panels. What you want to see instead is the polymer ETFE (Ethylene Tetrafluoroethylene) listed on the panel. 

Among other things, ETFE is more durable. This is certainly something you want to keep in mind if you are buying flexible solar panels to power outdoor activities where the elements will be a factor.

Conclusion

Ultimately, flexible solar panels are not the most efficient solar panels that are currently on the market. 

Their typical efficiency of 7-13﹪ falls below Polycrystalline panels’ 16-17﹪ efficiency and well behind Monocrystalline panels’ roughly 20﹪ efficiency.

However, it would be a mistake to discount flexible solar panels entirely. They are often the best choice for outdoor and on-the-go charging needs, including boat and RV installations. Often, they are the best choice for commercial roofing as well.

Although it is an important factor, efficiency is not the only detail to consider when selecting the right solar panel for you.

Hivan Team

As an independent team of travelers, we do share positive and negative observations as we find them and make our best to help and inform other vanlifers around the globe.

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