When we talk about commercial aluminum and glass works, such as building storefronts, shop fronts, or glass doors, we always suggest 8mm, 10mm, or 12mm thick tempered glass so that strength and security are perfect. However, if you look closely at a solar panel, a completely thin glass of only 2mm or 3mm is installed on top of it. Here, a very interesting question arises: "When glass thicker than 12mm is available in the market, why do solar panel manufacturing companies use such thin glass? If 12mm thick glass were installed on a solar panel, wouldn't it become much stronger?" In today's post, I will explain the 4 big technical reasons hidden behind this in simple language, in the light of my field experience and scientific facts.
1. Sunlight Transmission is the Biggest Reason
The primary function of a solar panel is to absorb sunlight and generate electricity. The thicker the glass is, the more sunlight it will absorb within itself and reflect away.
Benefit of 2mm Glass: A 2mm or 3mm glass allows 91% to 93% of sunlight to pass straight through it, due to which the solar cells underneath receive full sunlight and generate more electricity.
Disadvantage of Thick Glass: If we install 12mm glass there, a large portion of the light will be wasted within the thickness of the glass itself, which will severely affect the efficiency of the solar panel, and it won't be able to generate even half the electricity.
2. Iron Content and the Color of Glass
Generally, the thick 12mm glass that we use in windows or doors shows a slight green tint on its edges. This green color is due to the iron oxide present inside the glass.
The 2mm or 3mm glass installed on a solar panel is not ordinary glass; rather, it is called low-iron glass or ultra-clear glass.
The iron content is completely eliminated from this thin glass so that the glass remains 100% white and transparent.
If glass as thick as 12mm is made, the iron content has to be increased or its transparency decreases, which is harmful to solar cells.
3. The Technical Issue of Weight
An ordinary solar panel already weighs approximately 20 to 22 kilograms, which includes the aluminum frame of the panel and the underlying material.
If we install 12mm thick glass on the panel instead of 2mm glass, the weight of just a single panel will reach 50 to 60 kilograms.
Carrying such a heavy panel up to the roof, fitting it, and then making a heavy aluminum or iron structure to support their weight would not only become impossibly difficult but would also double the cost.
4. Heat Transfer and Temperature
Solar panels heat up in the sun, but the solar cells installed beneath them require a balanced temperature to function.
Thin glass (2mm) releases heat quickly.
In contrast, thick glass like 12mm traps heat inside itself, which will excessively increase the temperature inside the panel, and the solar cells will be permanently damaged due to the heat.
Does 2mm Glass Not Break from Hail and Storms?
It is a misconception of many people that 2mm glass is weak. The 2mm or 3mm glass used on solar panels is tempered. Due to the tempering process, this thin glass also becomes so strong that it easily withstands severe storms, high winds, and even the impact of thick hailstones falling from the sky. It is flexible and absorbs vibration upon impact, whereas 12mm glass, lacking flexibility, can crack quickly under a sharp impact.
Technical Summary
Glass thicker than 2mm cannot be used on a solar panel technically and scientifically. If you do so:
The panel's capability to generate electricity will be ruined.
The weight will become unbearable.
The panel will heat up and burn out.
Therefore, according to international standards, 2mm ultra-clear tempered glass is the only and best solution for the solar industry.
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