Why are my solar panels blue in color?

​You must have noticed that the color of the solar panels is generally blue. The function of the solar panel is to absorb the sunlight and convert it into the electric current. The more it absorbs the sunlight, the more it produces the electric current. 

​This is a fact that the black color absorbs the maximum light, you will feel more heat wearing a black T-shirt than wearing a red one. Despite this we find that the blue colored solar panels are more prevalent than the black ones

Silicon

​The silicon is generally used in making the solar panels. It is a non-metallic element with properties of absorbing most of the visible light and produce electricity.
There are two kinds of the solar panels:

• Polycrystalline solar panels (Blue in colour)
• Mono-crystalline solar panels (Black in colour)

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Out of total panels installed, almost 90% of them are poly-crystalline. Hence, we see blue colored solar panels around us. Well there is valid reasons for this, because it is relatively easier and cheaper to commercially produce them.

Reason

1. ​When the raw silicon in the molten form is poured in the molds, it does not settle and align perfectly rather forms many crystals of silicon hence called as poly-crystalline. Also, the nature of the silicon element is such that it absorbs most of the red and yellow light and reflects green and the blue light, thereby appears blue or greenish blue.
2. The other factor is the coating of anti-reflective layer over it. It has higher refractive index than air, so when the light falls on it some of its get reflected in the surroundings. The anti-reflective layer of Silicon Nitride and Silicon oxide is generally used to reduce reflection of light hence increasing the absorption capacity and the efficiency of the panel.

The combination of the above factors gives blue appearance to the poly-crystalline solar panels.

• In the black colored mono-crystalline solar panels, the silicon is aligned in the same way, forming the large single crystal of silicon. It has high light absorption capacity than the blue colored poly-crystalline solar panel hence appears black in color (black color absorbs more sunlight than the blue color). They are more efficient than the poly-crystalline solar panels.
• The mono-crystalline solar panels are expensive as the process involved in making them is costly and time consuming. Mono-crystalline panels have higher efficiency and are generally used where the more output is required at the limited space. Whereas the poly-crystalline solar panels are widespread due to their low prices.

​The manufacturing process along with coating of the anti-reflective layer give blue color to the poly-crystalline solar panels.

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• Are solar panels attractive investment or a big expense?​
• Do solar panels work in night and in cloudy weather?