Why are some solar panels blue vs. black?

Most solar panels have a blue hue, although some panels are black. The source of this color difference comes from how light interacts with two types of solar panels: monocrystalline and polycrystalline. In this article, we will examine what the color of a solar panel can tell you and what makes solar panels blue.

Solar panels are blue due to the type of silicon (polycrystalline) used for certain solar panels. The blue color is mainly due to an anti-reflective coating that helps improve the absorbing capacity and efficiency of the solar panels. Black solar panels (monocrystalline) are often more efficient as black surfaces more naturally absorb light.

The vast majority of modern solar photovoltaic panels are made using silicon, a non-metallic element that is used in most modern electronics. Silicon is used in solar panels partly due to its ability to absorb most wavelengths of light and produce an electric charge. We can also manufacture near-perfect crystals at a relatively low cost. Differences in solar panels come from many sources, mainly the purity of the silicon used in the module. Most solar panels have a blue hue and are made with polycrystalline silicon, while the smaller percentage that appears black is made with monocrystalline silicon.

Polycrystalline (blue) solar panels

The silicon used in polycrystalline solar cells is made from raw silicon that has been melted and poured into a square mold. This process doesn't align the silicon perfectly, which results in the formation of many individual silicon crystals within the mold. The nature of the respective silicon crystals also produces the speckled, glimmering look and blue color characteristic of polycrystalline panels.

The polycrystalline cell manufacturing process leads to less waste and energy use than that needed to produce monocrystalline cells. As a result, polycrystalline solar panels are less expensive and much more widely used. Due to the lower cost of polycrystalline solar panel production, about 90 percent of the solar panels on the market today are polycrystalline; consequently, most solar panels have a blue hue.

Monocrystalline (black) solar panels

The silicon used to make monocrystalline solar cells has a high level of purity. The silicon is all oriented the same way in a monocrystalline solar cell, creating one large silicon crystal. Because of how light interacts with a monocrystalline silicon layer, monocrystalline solar panels appear black. Aligning the silicon into one crystal, known as the Czochralski process, is energy-intensive and results in some wasted silicon. As a result, monocrystalline panels cost more than polycrystalline solar panels.

Black monocrystalline and blue polycrystalline solar panels both offer unique benefits and drawbacks. Due to their uniformity and the alignment of silicon in monocrystalline solar cells, monocrystalline panels tend to have a higher efficiency than polycrystalline panels. However, this higher efficiency comes with a higher price tag, as monocrystalline solar panels are generally more expensive to produce and buy. Polycrystalline solar panels have a less intensive production process (the silicon is less pure and doesn't need to be aligned), leading to lower prices for consumers and installers.

If efficiency is your main concern, a monocrystalline solar setup may be your best option. Likewise, if you want the lowest price for your solar project, polycrystalline panels could work best. For more information on their differences and which is best for you, check out EnergySage's comparison of black monocrystalline vs. blue polycrystalline solar panels.

If aesthetics are important to you, the difference between black monocrystalline and blue polycrystalline panels may make a difference in your solar shopping decisions. On the EnergySage Marketplace, you can create a property profile to solicit quotes from solar installers and even leave notes on your profile if you want a certain type or color of solar panel. Our qualified, vetted installers offer many types of solar installation and can work with you to customize your home solar solution.