Solar Panel Light Absorption Band Range
Solar panels have become increasingly popular in recent years. They are a cost-effective, environmentally-friendly, and renewable source of energy. Solar panels convert sunlight into electricity by using a special material called a solar cell. The solar cell is made of different materials that can absorb different wavelengths of light.
Light Absorption in Mono-crystalline Silicon Solar Cells
Mono-crystalline silicon is a high-performance solar cell material. It has a high purity level and a uniform crystal structure, which allows for better electron mobility. Mono-crystalline silicon solar cells typically have a light absorption range of 300 – 1100 nm, with the peak absorption band located at around 780 nm. This means that the solar cells can absorb most of the visible light spectrum, as well as some of the near-infrared light.
However, there is a noticeable drop-off in absorption efficiency beyond 1100 nm. This is due to the fact that mono-crystalline silicon is an indirect bandgap material. Indirect bandgap materials have a higher energy threshold for electrons to move from the valence band to the conduction band. This means that photons with lower energy cannot be absorbed effectively by the material. Therefore, mono-crystalline silicon solar cells are not able to absorb a significant amount of the longer-wavelength (lower energy) light.
Light Absorption in Thin Film Silicon Solar Cells
Thin film silicon solar cells are made of multiple layers of silicon with varying thicknesses and dopants. They are typically less expensive to manufacture than mono-crystalline silicon solar cells. The light absorption range of thin film silicon solar cells is different from that of mono-crystalline silicon solar cells. Thin film silicon absorbs light in a broader range of wavelengths, specifically in the range of 400 – 800 nm. This means that they can absorb most of the visible light spectrum, but not as much of the near-infrared light as mono-crystalline silicon.
Thin film silicon solar cells can be further categorized into three types: amorphous silicon (a-Si), micro-crystalline silicon (μc-Si), and nano-crystalline silicon (nc-Si). Each type has a different bandgap and absorption range. Amorphous silicon has a bandgap of about 1.7 eV and can absorb light in the range of 300 – 800 nm. Micro-crystalline silicon has a bandgap of about 1.3 eV and can absorb light in the range of 400 – 700 nm. Nano-crystalline silicon has a bandgap of about 2.0 – 2.2 eV and can absorb light in the range of 300 – 600 nm.
In conclusion, mono-crystalline silicon solar cells have a peak absorption band located at around 780 nm and can absorb most of the visible light spectrum as well as some of the near-infrared light. Thin film silicon solar cells, on the other hand, have a broader absorption range than mono-crystalline silicon, but not as much near-infrared light. The specific absorption range and efficiency depend on the type of thin film silicon. Regardless of the type of solar cell, solar panels provide a sustainable and renewable source of energy. With further advancements in technology, solar panels will be able to provide an even greater amount of energy with even greater efficiency.