Why Are Some Solar Panels Blue vs Black?

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.

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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.