It can be difficult to decide between different types of solar panels. It’s a good problem to have: you have a lot of options to choose from when picking solar panels for your house, solar powering your RV, or starting a DIY solar project.
This article will break down the 3 main solar panel types available today, comparing their efficiency, price, and best uses. Let’s get started.
Types of Solar Panels
The 3 main types of solar panels on the market today are:
- Monocrystalline
- Polycrystalline
- Thin-film
Monocrystalline and polycrystalline solar panels are made of silicon solar cells packed into a frame and covered with glass or plastic. They’re currently the most common types of solar panels.
Thin-film solar panels are made of a thin layer of a photovoltaic substance laid onto a surface of glass, plastic, or metal. They can be made of a variety of organic or inorganic compounds, which range widely in efficiency and price per watt. They’re less common than silicon solar panels and can be difficult to find.
I’m constantly reading exciting scientific reports about breakthroughs in the development of perovskite, biohybrid, and (my favorite) quantum dot solar panels. But you’re not likely to find any of these new solar panel types on the market for at least a few years.
Comparison Table
| Monocrystalline | Polycrystalline | Thin-film | |
|---|---|---|---|
| Efficiency | 20-23% | 15-17% | 6-15% |
| Price | $1 to $1.50 per watt | $0.90 to $1 per watt | $0.40 to $2 per watt |
| Color | Black | Blue | Blue or black |
| Pros | • High efficiency • Decent performance in high temperature | • Good value for the money • Decent efficiency | • Can be inexpensive • Lightweight • Best performance in high temperatures |
| Cons | • Pricier per watt than poly panels | • Larger and heavier than mono panels • Worst performance in high temperatures | • Difficult to find • Shortest lifespan • Low efficiency |
| Best Uses | • Houses and roofs • RVs, vans, and boats with limited mounting space • Camping and other portable uses • DIY solar projects | • Houses and roofs with lots of mounting space • Ground-mounted solar arrays • Camping and other portables uses • DIY solar projects | • Curved or irregular mounting surfaces |
Monocrystalline Solar Panels
Monocyrstalline solar panels are the more efficient, yet more expensive, version of silicon solar panels. They’re best suited for a wide range of uses, such as roofs and houses, DIY solar projects, and RVs and vehicles with limited mounting space. They are most often rigid, but portable and flexible monocrystalline solar panels are also available.
Each cell in monocrystalline solar panels (also called mono solar panels) is a thin wafer of a single crystal of nearly pure silicon. The wafer is coated with other elements, such as boron and phosphorus, so that it has positively and negatively charged sides, known as a PN junction. Silver wires painted onto the wafer allow for electricity to flow once sunlight knocks loose electrons from the silicon atoms.
Monocrystalline panels are usually black in color because the cells’ uniform alignment absorbs more sunlight and refracts less. Many manufacturers also use “black silicon,” where nano-sized needle shapes are etched into the surface of the silicon wafers. This allows for greater absorption (and less reflection) of light, in the same way that a sponge traps water in its pores.
Polycrystalline Solar Panels
Polycrystalline solar panels are best when you are on a budget or have lots of mounting space. They are less efficient than comparable monocrystalline solar panels, so they need to be bigger to produce the same amount of power.
However, they have a lower price per watt. Like monocrystalline panels, they have a wide range of uses, from residential solar installations to ground-mounted solar arrays.
The PV cells in polycrystalline solar panels (also called poly solar panels) are made of fragments of silicon that are melted together to form wafers made of several smaller crystals. The manufacturing process is less error-prone than shaving wafers off of a single crystal, so it wastes fewer raw materials.
Being manufactured from multiple crystals, polycrystalline cells scatter light to produce a blue color (the shortest light wavelength), just as our atmosphere scatters light to make the sky look blue. The anti-reflective coating used on polycrystalline panels also creates a blue hue.
Because of their popularity and wide availability, you often must pick between monocrystalline and polycrystalline solar panels. Check out our full breakdown of these 2 types of solar panels to decide which is best for you.
Full breakdown: Monocrystalline vs Polycrystalline Solar Panels
Thin-Film Solar Panels
Thin-film solar panels vary widely in price and efficiency based on their material. Their thinness makes them well-suited to curved or irregular mounting surfaces. They’re much less common than silicon panels, though. If you’re buying solar panels yourself, thin-film panels aren’t easy to find.
Note: Many people wrongly assume that all flexible solar panels are thin-film solar panels. While thin-film panels are often flexible, most flexible panels on the market today are in fact monocrystalline solar panels.
As the name suggests, thin-film panels are films of photovoltaic materials rather than crystals. They can be made of different elements, the most common of which are amorphous silicon, cadmium telluride, copper indium gallium selenide, and gallium arsenide. They can be made of organic materials as well.
Here’s a quick overview of some of the main types of thin-film solar panels:
- Cadmium telluride (CdTe) panels are the most common thin-film solar panel technology. They are easy to manufacture and can have efficiencies nearly as high as silicon panels. While the materials are inexpensive to use, cadmium is a toxic and carcinogenic heavy metal which requires extra care in manufacturing. Research is underway to replace cadmium in thin-film panels with other materials.
- Amorphous silicon (a-Si) is flexible and uses fewer toxic materials than other thin-film solar panels. It’s more efficient than most panels at absorbing light in partial sunshine, though they are overall only around 7% efficient. They also have a shorter lifespan of 10 to 20 years.
- Copper indium gallium selenide (CIGS) absorbs light more strongly than other thin-film panels, and has an efficiency that is comparable to silicon solar panels. It is flexible and lightweight. But CIGS panels also contain cadmium.
- Organic photovoltaics (OPV) have been around since the 1980s, but they are only now reaching marketability. They are made from a mix of organic and inorganic materials, and can be up to 19% efficient at capturing sunlight and converting it into electricity. They can even be transparent! Currently, only a few startups around the world make OPV panels. With growing concerns about toxic materials, supply chains, and the end-of-life disposal of solar panels, I expect the popularity of OPVs to grow.
Types of Solar Panels by Efficiency
Note: Efficiency refers to how well solar panels convert sunlight into electricity — not how much power they output. A 100 watt solar panel will output 100 watts under ideal conditions, regardless of what type of solar panel it is. Instead, more efficient solar panels require fewer solar cells to produce the same amount of power, and are thus usually smaller in size.
Monocrystalline solar panels more efficiently convert sunlight into electricity than polycrystalline solar panels do – up to 22-23% efficient for the former compared to 17% for the latter.
Thin-film panels are generally the least efficient type of solar panel, ranging from 6-15% efficiency depending on the materials used.
How solar panels respond to temperature — a measure called temperature coefficient of Pmax, or simply temperature coefficient — is a key factor affecting their efficiency. While all panels are tested under the same standard test conditions, real-world temperature can affect different types (and brands) of panels in varied ways.
All panels output less power as temperatures rise, but in general, monocrystalline panels do better in higher temperatures than polycrystalline panels do. Thin-film panels handle rising temperatures the best.
Types of Solar Panels by Price
The cost of solar panels is measured in dollars per watt. Monocrystalline panels are more expensive per watt than polycrystalline ones because it costs more (and is more wasteful of raw materials) to shave a thin wafer off a single silicon crystal than it is to fuse together silicon fragments. The manufacturing process is simplest in making thin-film panels, however, so they generally cost less than crystalline panels.
| Solar Panel Type | Price per Watt | Efficiency |
|---|---|---|
| Monocrystalline | $1 to $1.50 | 20-23% |
| Polycrystalline | $0.70 to $1 | 15-17% |
| CdTe | $0.50 to $0.60 | 9-11% |
| a-Si | $0.43 to $0.50 | 6-8% |
| CIGS | $0.60 to $0.70 | 13-15% |
Types of Solar Panels by Form Factor
When I picture a standard solar panel, I imagine the rectangular ones that are used for residential rooftop installations and solar farms. But those are only one of the options you have for generating your own solar energy. Here are the most common form factors that solar panels come in.
Conventional Rooftop Solar Panels
Conventional solar panels for roofs and houses are set in an aluminum frame, covered with a glass sheet, sealed with encapsulants, with a backsheet at the back of the frame. A junction box attached to the frame will connect the panel to an electric circuit.
Some panels also come with micro-inverters on their backing. More common are string inverters that are separate from the panels, which are wired in a series. Anyone who has strung Christmas lights probably knows the benefits of wiring in parallel rather than series: micro-inverters are more expensive, but when one goes down, your whole circuit doesn’t go down.
Bifacial Solar Panels
As their name implies, bifacial panels have crystalline cells on the back of the panel in order to capture any light reflected off the surface below the panels. (Think about it: if light didn’t reflect off the ground below solar panels, you wouldn’t be able to see the ground.)
Reflected light is weaker than direct light, of course, but it’s enough to make a difference: bifacial panels can generate up to 9% more electricity than traditional monofacial panels. Bifacial panels use glass instead of metal frames, and the glass itself isn’t coated with a dark color, allowing more light to pass through. Usually, the back side of a bifacial panel shares the same circuitry as the front side.
Ground-Mounted Solar Panels
Ground-mounted solar panels are conventional panels set in a free-standing solar array, mounted either on top of a single pole or in a rigid metal frame. A ground-mounted system has the added cost of the mounting materials, but allows easier access for cleaning and maintaining the panels.
Ground-mounted systems might also have solar trackers to change the angle and direction of the panels to follow the path of the sun throughout the season and day. Again: more cost, but also more electricity generated.
Portable Solar Panels
Portable solar panels are typically smaller and less expensive than rooftop panels, and can range from sizes as small as 5 watts to up to 200 watts or more. One of the most common sizes is the 100 watt solar panel, which is used often with RVs, camper vans, solar generators, and DIY solar projects.
Portable panels sometimes come with built-in USB ports for charging phones and portable battery packs. They can be a single panel or a triptych of three foldable panels, encased in a mesh fabric or plastic.
Flexible Solar Panels
You might think that flexible solar panels use thin-film technology. Some of them do. But more often than not, flexible panels use monocrystalline cells that are far thinner—only a few micrometers—than those in rigid panels. Flexible panels also use protective plastic rather than glass. They tend to be more expensive than rigid panels.
Because of their form factor, flexible solar panels are best used on curved mounting surfaces, such as boat hulls or teardrop campers. They’re also much lighter than rigid solar panels, so they can be the right choice when you need to minimize the weight of your solar system.
Types of Solar Panels by Use Case
| Form Factor | Use Case |
|---|---|
| Conventional rooftop | Rooftops or ground-mounted arrays |
| Bifacial | Mounted on a hard surface that reflects light, like concrete |
| Ground-mounted | Cases where roofs lack space, sunlight, or structural integrity; solar farms |
| Portable | Camping, hiking, apartment living, short-term uses |
| Flexible | Boats, teardrop campers, curved surfaces |
Your choice of solar panels will depend largely on what you want to use the panels for. Crystalline panels (of both types) generally come in rigid frames better suited for rooftops and stationary installations, while thin-film panels are better suited for portable and flexible installations.
But “generally” does not mean always: you can find flexible crystalline panels and rigid-framed thin-film. And any type can be portable if it’s small enough. Nonetheless, these panels are generally more suitable for these applications:
- Rigid panels are heavier, so they need structural support like a roof or a ground-mounted frame. A single rigid panel is certainly portable, but not conveniently so.
- Bifacial panels need ground clearance to capture reflected light. You don’t need to be a rocket scientist to know that lighter colors reflect light better than darker ones, so a surface like a white-painted roof or concrete surface works better than ordinary soil.
- Ground-mounted panels are ideal when roofs lack space, sunlight, or structural integrity, and where land is available with better exposure to the sun. They’re typically also used in large-scale projects such as solar farms or actual farms, where crops can be grown under them or animals can graze.
- Portable panels are ideal if you live in an apartment, have a boat, or go camping. They are also good for temporary uses. If you live somewhere where power outages are frequent, like I do in Maine, you can continue to run a modem and a laptop with a battery backup powered by portable panels, or even solar power a small refrigerator. Just don’t assume you can keep an entire house running on a few portable panels, since the average American home uses 30 kWh of electricity per day.
- Flexible panels bend, letting you install them on curved surfaces, such as the deck of a boat or the top of a camper. Some flexible panels have an adhesive backing, which makes for easy, peel-and-stick mounting.
What Type of Solar Panel Is Best for You?
Monocrystalline solar panels are worth the money when you have space constraints, or when you want solar panels that perform well in higher temperatures. They’re usually high-quality, so if you want an all-around great solar panel, mono panels are a good option.
Polycrystalline panels are great when you have lots of mounting space or are on a budget. They don’t perform as well as mono panels in higher temperatures, though. Both monocrystalline and polycrystalline solar panels work well for a range of uses, such as rooftop solar installations, RVs and other vehicles with limited mounting space, portable solar systems, and DIY solar projects.
Thin-film panels are much less common, but may be a good option if you have curved or irregular mounting surfaces. Their efficiency and price per watt vary widely based on material, and they can be hard to find if you’re buying your solar panels yourself.
