Types of solar panels: The efficient, the cheap and the flexible

Different types of solar panels on a market can make a choice for a potential customer confusing. After all, they all have their advantages and disadvantages: some are suited best for one situation, and you would prefer another type in different circumstances. This article will help you to learn more about solar panels types and ease your decision.

How to decide what type of solar panels to get

There are 3 main types of solar panels: monocrystalline, polycrystalline and thin-film solar panels, plus there are some special cases that are not so widely spread. These types vary in cost, performance, aesthetics and durability that determine their lifespan. Let’s look at each one in more detail.

Monocrystalline solar panels are the most efficient

Monocrystalline panels stand out in line because of their amazing performance. Their efficiency often exceeds 20%. Making monocrystalline panels is a slow and expensive process: a single crystal of silicone is sliced into wafers that are used to make solar cells. A panel usually contains 60, 72 or 96 cells. Edges of a panel are rounded. Black panels look stylish and sometimes their design is what makes customers choose them.

The biggest drawback of monocrystalline panels is their cost. Although their efficiency is higher it doesn't always make the payback time is shorter. Generally, they sell for 5 cents higher per watt than polycrystalline ones. Their lifespan is the highest, and the warranty for them can be issued for up to 25 years. One of the companies that stand behind their products is Panasonic. Their 370W EverVolt Solar Panel enjoys a TripleGuard warranty that covers performance, product, parts and labor for exactly 25 years.

Monocrystalline panels are the best choice when space on the roof is limited or when a roof can't withstand high weights. Due to the same reasons they are oftentimes used on ships. Their construction allows them to perform well even in low-light situations — like bad weather or during months of fall.

Polycrystalline solar panels are cheaper

Polycrystalline panels have one big difference production-wise when compared to monocrystalline ones. Instead of a single crystal, a block of silicone is being used. They also contain from 60, 72 or 96 cells. A completed panel generally has a square shape and blue in color. Frames are often silver or white. This design doesn't always appeal to customers in contrast to much more stylishv black monocrystalline panels. So the appearance might be called a drawback for polycrystalline panels.

Because of the use of multiple crystals, the performance of polycrystalline panels drops a little. Usually their efficiency has a range from 15% to 20%. However, the production process is much cheaper, which is reflected in the cost — they are 20-25% cheaper than monocrystalline panels. Their durability is on par with monocrystalline panels and they can easily last for 25 years or longer. They are a great choice for those who aren't ready to invest a lot into solar energy and often give the fastest payback time.

Thin-film solar panels are modern, flexible and thin

Thin-film solar panels are much more different than monocrystalline or polycrystalline ones. In the process of making them photovoltaic material is being applied onto glass or metal substrate. This modern technology allows thin-film panels to be the cheapest of all types, plus they are the easiest to install. 

In theory these panels are very thin, however it depends on substrate and varies from model to model. They also can be quite flexible, unlike other types of solar panels, and very light-weight. Thin-film solar panels can vary in appearance and can be black or blue, depending on a particular model. Unlike other examples, they aren’t produced with a fixed number of cells, which depends on their size.

Being the cheapest comes with the cost: thin-film solar panels have the lowest efficiency of all types. It usually varies around 10%-13%. What is more, their lifespan is considerably shorter — they usually don’t last longer than 20 years, which means that an owner might have to replace them more often. In most cases they are not suitable for residential use — there is not enough space to justify using them. However, they are a great choice for mobile installations.

Let’s take a look at three main types of thin-film solar panels.

Amorphous silicon (a-Si) thin-film

Unlike traditional crystalline silicon solar cells, a-Si solar cells don't require a perfect crystalline structure. This makes them more flexible and easier to manufacture on various substrates like glass, metal, or even flexible plastic.

These panels are particularly well-suited for warmer climates as they can withstand high temperatures and perform reasonably well in low-light conditions. But they have a shorter lifespan of 10-20 years and lower efficiency around 7% compared to other solar technologies.

Cadmium telluride (CdTe) thin-film

Cadmium Telluride (CdTe) thin-film solar cells are the second most widely used type globally after crystalline cells. CdTe solar cells can achieve high efficiencies, often surpassing 18% and approaching 20% in commercial modules. This makes them competitive with crystalline silicon solar cells. Yet, cadmium is a toxic heavy metal, and its use in solar panels raises concerns about environmental impacts during manufacturing, disposal, and recycling.

Copper gallium indium diselenide (CIGS) thin-film

CIGS thin-film solar panels are the most efficient type of thin-film panels. In a lab, CIGS solar cells can achieve over 23% efficiency, which makes them well competitive with crystalline silicon solar cells. They are a good option for those who are looking for the highest possible energy output. The only problem with them is availability of indium and gallium, two key elements in CIGS. This makes them the most expensive type of thin-film panels.

Passivated emitter and read cell panels (PERC) absorb more sunlight

PERC panels are a type of monocrystalline solar panel that uses a passivation layer on the rear side of the cell to improve efficiency. This technology allows PERC panels to achieve higher efficiency than standard solar cells, typically around 20-22%. PERC cells also generate more power in low-light conditions, such as early morning, late afternoon, and cloudy days, and are also less affected by temperature changes, which can improve their performance in hot climates.

Solar panel types by efficiency, cost, power output, and appearance  

Now that we have looked closely at each type of most widespread solar panels, we can use a chart to make this information look more structured.

Integrated and bifacial solar panels — for special cases

While these three types of solar panels are the most prominent, there are other options that can be good in certain situations. For example, there are integrated solar cells. These are used in times when the appearance of a building shouldn't be affected by solar panels at all so they are built into walls or a roof. These building-integrated photovoltaics (BIPVs) are expensive and considerably less efficient than other counterparts but let you keep the original design of a house or a building. This might be a good option for those who are considering building a new home from scratch.

Bifacial solar panels can be counted as a subcategory of monocrystalline or polycrystalline panels. Their distinctive feature is the ability to capture the sunlight with its back side as well the front. It makes them on average 11% more efficient than comparable polycrystalline/monocrystalline modules. 

Bifacial panels often have a transparent black sheet, so that sunlight can go through the panel and reflect from the ground back onto the panels. They are rarely useful for homeowners who consider a rooftop installation, but can be effective as ground-mounted systems. They are best suited for commercial or utility-scale use.

Some models are too modern for now

There are new types of solar panels that are currently being developed and in the future they might replace those that are more common now. Right now they are either not ready or too expensive for residential use to even take them into consideration. 

For example, there is Biohydrate Solar Cell technology, which emulates the process of natural photosynthesis (right now in development). Concentrated PV cells take advantage of mirrors, lenses, cooling systems and solar trackers, which allow them to reach the efficiency of 41%.

Other factors to consider when comparing panel types

Every model of solar panel undergoes testing before going on market. Apart from tests on efficiency, engineers check on how panels are made to endure extreme conditions. 

Hail rating 

Solar manufacturers certify and test their panels to withstand hail. To pass US standards, PV modules must be able to withstand the direct impact of hailstones about 1 inch in diameter falling at 50 mph. This is more than enough for most storms, and even stronger than a typical shingle roof. 

Larger hail stones can crack the glass. If the panels are insured against hail, the insurance will cover the damage. It’s important to angle your panels for the hail to bounce. About 50% of solar panel losses are attributed to hail damage. Read more in the article: “Can your solar panels survive a hailstorm?”

Hurricane rating 

Most well-made and properly installed solar panel systems can survive Category 3 hurricanes, with winds up to 130 mph. Some reinforced panels may even survive Category 4 storms. 

Solar systems may appear complicated. First, you have to choose all these different elements and make sure they match. Then, the installation starts and it also can be stressful and time-consuming. Here is the good news: a system made of AC solar panels is much simpler. Well, is there any bad news? What are these ACpanels anyway? Let's find out.

Tornadoes are much more difficult to predict than hurricanes, and the damage they cause can be highly localized. Solar panels can typically withstand the winds of weak tornadoes F0 and F1 and may even survive some F2 tornadoes. However, a direct hit from a strong tornado will likely damage or destroy any solar panel system. Read more in the article: “How to make solar panels and hurricanes tolerate each other”.

Temperature

The ideal operating temperature for solar panels is 25 °C or 77 °F. For each degree after 25 °C, a solar panel loses a fraction of its output. Their ability to retain it can be measured through their temperature coefficient. 

For monocrystalline and polycrystalline panels the coefficient ranges from -0.3 % to -0.5% per degree after 77. For example, if the temperature of your modules rises to 87 degrees, they lose from 3 to 5% of their efficiency. Thin-film panels are more resistant: their temperature coefficient is closer to -0.2%. Keep in mind that the temperature of panels installed on the roof is much higher than ambient temperature. Read more in the article: “Too much sun: What is temperature coefficient of solar panels”

Fire rating 

Solar panels themselves are not inherently fireproof, but they are generally classified as Class C fire-rated materials. This means they can resist a small flame for a short period, but they will eventually ignite if exposed to a larger fire.

Manufacturer matters

Now that you know more about the properties of different types of solar panels, it’s easier to answer the question “Which one should I choose?” For residential use the best option is usually monocrystalline panels. However if you’re tight on funds, polycrystalline panels are a fine choice. Don’t forget that it is possible to save 30% of the installation cost with Federal Solar Tax Credit (read about it in our article). 

Of course, in a lot of cases the brand and the manufacturer matter more than the type of a panel. Just as solar panels are different, companies stand out in different ways. For example, Panasonic PV modules are known for their improved performance at high temperatures — when it gets hot, they lose 2 times less production than average modules. The products of Canadian Solar excel in low-light situations — some of their models lose no more than 3% even on cloudy days. Trina Solar offers solar panel systems that have outstanding efficiency. The key to making the right choice is to focus on main factors that are most important in your particular case.

Andrey Gorichenski

Senior Editor

Andrey had been a news editor and freelance writer for a number of medias before joining A1 SolarStore team. Climate change and its impact on people's lives has always been among his interests and it partially explains his degree in Philosophy and Ethics.

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