The solar industry has been expanding in recent years, due to solar panels gaining popularity as a renewable alternative to generate electricity. It is becoming more and more common to see solar panels on rooftops. Moreover, you may perceive that newest solar photovoltaic (PV) modules look darker than older models, which makes people think that solar panels are usually black these days.
The popularity of solar energy has caused companies to look for ways to improve the design of solar panels to make them more attractive for residential and commercial use. This led to the development of solar panels with darker look than other types of PV panels known as “all-black solar panels”. These are better looking than older models, especially when installed on houses and business with modern design.
Nevertheless, it is important to know that these new “black” panels are not always in that color. In this article, we will learn about the true reason why solar panels are perceived as black, and we will answer some frequently asked questions that you may be asking yourself.
Are Solar Panels Always Black?
Types of Solar Panels
Currently, there are three main types of solar panels available on the market: monocrystalline, polycrystalline and thin-film.
Monocrystalline panels are made from a single pure silicon crystal. The use of pure silicon also makes these panels the most space-efficient and longest-lasting among all three types. However, a lot of silicon is wasted to produce one monocrystalline cell, leading to a higher price.
Polycrystalline panels come from different silicon crystals instead of one. The silicon crystal fragments are melted into a square mold, making these cells more affordable since there is hardly any wastage, and giving them their characteristic square shape. However, this also makes them less efficient than monocrystalline ones in terms of energy conversion and space.
Finally, thin-film panels are characterized by very thin and flexible layers, which make these panels perfect for portable applications. However, they are less efficient than the silicon solar panels previously mentioned.
Why Solar Panels Look Black?
Monocrystalline and polycrystalline panels are the most used models for rooftop solar applications; thus, we will focus mainly on these two.
The dark color in solar panels originates from the method used for their manufacture. Both types of silicon-based panels are elaborated by a process known as the Czochralski Method, which consists on melting silicon along with other conducting components at high temperatures.
In this process, a silicon ingot is formed. On monocrystalline panels, a single pure silicon crystal in cylindrical shape is used and later cut into several wafers. Polycrystalline panels, on the other hand, are created using multiple silicon crystal fragments that are melted into a square mold.
That difference on the manufacturing process is what makes the variation between colors on both solar panels. While polycrystalline panels do have a clearly visible blue color, monocrystalline panels have a deep dark blue tint, appearing almost black to the eye. These color characteristics on panels are due to how light interacts with the crystals when it reaches the modules.
The silicon used in polycrystalline panels does not align perfectly, which results in the formation of many individual silicon crystals within the mold and also produces the blue color characteristic of these panels. On the other hand, silicon used to manufacture a monocrystalline panel is all oriented in the same direction, creating one large silicon crystal. This single layer grants monocrystalline panels their dark look.
Traditional Monocrystalline vs All-Black Solar Panels
Now, when we said that the solar industry was searching for ways to improve aesthetics of the solar modules, we were talking about all-black solar panels. But what is the difference between this new technology and traditional monocrystalline ones?
The answer is that all-black solar panels are based, in fact, in monocrystalline technology, with the main difference of being completely black. Traditional monocrystalline modules have a silver frame and white backsheet, while all-black panels have a purely black backsheet and black frames.
All-black panels are manufactured using the same procedures as their traditional counterpart, with the exception that they use black adhesives around their electronic components and junction boxes. However, there is another characteristic that distinguishes both types of panels.
The white grid lines in the white backsheet monocrystalline panel actually contributes on the solar power production due to a “light-trapped” phenomenon caused by the light that reaches those white grid lines. This light gets reflected and it is used to harvest electricity. On the other hand, since the backsheet of all-black panels is entirely black, there is no light reflected by grid lines, which means, solar cells can only harvest electricity from the light that directly hits the solar cells.
This means that all-black panels will be less efficient when compared with white backsheet monocrystalline ones with the same properties. All-black panels can lose around 3% of electrical photocurrent generation, which translates in about 0.5% of efficiency loss.
In this article, we learned why most people think panels are black and we have learned that they are actually blue or dark blue. We also got to know the different types of monocrystalline panels (traditional and all-black) some looking totally black, while the others having the typical white color grid lines.
Furthermore, we learned about some of the most important applications of thin-film to improve aesthetics by changing colors (other than blue or black) on BIPV projects or even with new solar roof tiles.
Finally, it is important to remember that the plus in aesthetics for all-black panels comes at a decrease of power output due to the reduce of light reflection. This is one of the many considerations you must take into account when asking yourself if all-black solar panels are worth it.
Frequently Asked Questions
The ambient temperature of the location influences the operating temperature of a panel. The higher the ambient temperature, the higher the operating temperature of the panel will be. However, another fact comes into the scenario and that is the solar panel color.
Due to the black body theory, all dark colors tend to absorb more heat than light colors. Since all-black panels are entirely black, they are most likely to take up more heat energy from the sun when compared with traditional monocrystalline or polycrystalline panels with the same temperature coefficient and the same ambient temperature.
Currently, Tesla has been working on the development of “Solar Roof Tiles”, a technology that can look exactly the same as current terracotta or slate tiles, but can produce electricity on a substantial level, just like traditional solar panels can do.
Via they addition of a dichroic film, thin-film solar panels are capable of generating multiple colors other than black or blue and can get use on window applications. This is the reason why these thin-film glasses are used for building integrated photovoltaic (BIPV) projects allowing a varied color spectrum that can go from blue, red, green, orange and even yellow.
Concerning all-black panels, many homeowners of high-end houses do not want to sacrifice the look of their house by placing solar panels (even less when considering the light blue polycrystalline ones).
If you are one of those homeowners with high-end houses and you have the extra budget, then you may want to consider the premium cost for the all-black solar panels, especially if the panels will need to be installed in the front side of the house.
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