How the Next Big Solar Panel Tech is Already Here

Summary

CdTe (cadmium telluride) solar panels are a lesser-known but efficient alternative to silicon-based solar panels, offering advantages like thinner construction and lower production costs. Though CdTe has slightly lower efficiency than silicon, it excels in durability, requiring less material and offering fast energy payback times. First Solar, a leader in CdTe technology, is driving innovations to improve efficiency, reduce environmental impact, and recycle materials. Despite challenges like efficiency and material scarcity, CdTe is gaining traction, especially in large-scale solar projects, with the potential to become a strong competitor to silicon in the future.

Takeaways

• 😀 CdTe (Cadmium Telluride) is the second-most common type of solar panel technology after silicon, but it's often overlooked despite its potential.
• 😀 CdTe is made from cadmium and tellurium, both toxic elements that are safe when combined in the CdTe compound, similar to how table salt is formed from sodium and chlorine.
• 😀 CdTe panels are thinner and more efficient at absorbing sunlight compared to silicon, making them cheaper to produce and lighter in weight.
• 😀 CdTe panels have an efficiency of around 18.6%, with lab versions reaching up to 22%, which is slightly behind silicon but still competitive, especially when thinned down.
• 😀 One of CdTe's biggest advantages is its durability, with First Solar claiming their panels maintain over 89% of their original performance after 30 years.
• 😀 Despite being more reliable and easier to produce, CdTe faces challenges like lower efficiency than silicon and the rarity of tellurium, which limits scalability.
• 😀 CdTe panels are gaining traction in the U.S., but globally, they only account for about 4% of the solar panel market, compared to 21% in the U.S.
• 😀 First Solar, a major producer of CdTe panels, is pushing the technology forward, with plans to improve efficiency to 25% by 2025 and potentially 28% by 2030.
• 😀 One of the key benefits of CdTe is its low carbon and water footprint, making it a more environmentally friendly option compared to silicon panels.
• 😀 CdTe faces competition from perovskite solar panels, which offer higher efficiency but are fragile and less durable, whereas CdTe maintains better reliability over time.
• 😀 China is showing increasing interest in CdTe technology, with major investments from companies like Advanced Solar Power and Flat Glass Group, signaling that CdTe may play a more significant role in future solar installations.

Q & A

What is cadmium telluride (CdTe) and why is it used in solar panels?

Cadmium telluride (CdTe) is a semiconductor material made from cadmium and tellurium. Despite being toxic in their individual forms, when combined into CdTe, they are safe to use. CdTe is used in solar panels due to its efficient light absorption properties, which allows panels to be thinner, cheaper, and more efficient than traditional silicon-based panels in some cases.

How does CdTe compare to silicon in terms of solar panel efficiency?

CdTe panels generally reach efficiencies around 18.6%, with laboratory versions reaching up to 22%. This is slightly behind silicon, which has an average efficiency of 20-24%. However, CdTe panels can be made thinner, and their efficiency is less affected by thin-film designs, which is a major advantage over silicon.

What is doping, and how is it used to improve CdTe panel performance?

Doping is the process of introducing small amounts of a different material into a semiconductor to enhance its properties. In CdTe panels, doping is used to improve efficiency, typically by adding copper or arsenic. This process helps increase the material’s conductivity and performance, but it can also shorten the lifespan of the panels due to the instability introduced by copper.

What challenges do CdTe solar panels face in terms of durability and efficiency?

While CdTe panels are more durable than perovskites, they face challenges in terms of efficiency and longevity. The copper doping process can degrade the material's structure over time, and CdTe panels generally need to be larger than silicon panels to generate the same amount of power. Additionally, there are challenges in boosting the open circuit voltage (Voc) and overall efficiency.

What is Physical Vapor Deposition (PVD), and why is it important for CdTe solar panels?

Physical Vapor Deposition (PVD) is a manufacturing process where materials are heated under a vacuum to vaporize them, then condensed onto a cooler surface to form a thin, uniform film. This method is essential for CdTe solar panels as it allows for efficient, high-speed production of the thin films required for solar cells.

Why is tellurium considered a limiting factor in CdTe solar panel production?

Tellurium is a rare element, as common as platinum, and is mostly found as a byproduct of copper mining. Although it isn't expensive, its rarity makes it a limiting factor in the scalability of CdTe solar panels, and as demand grows, there may be challenges in sourcing enough tellurium for large-scale production.

How does CdTe compare to perovskite solar cells in terms of efficiency and durability?

Perovskite solar cells can achieve efficiencies up to 26.7%, surpassing CdTe's 22% efficiency in labs. However, perovskites are fragile, degrade quickly under heat, moisture, and sunlight, whereas CdTe panels are more durable, making them a better choice for long-term solar installations, especially in regions with extreme conditions.

What is the environmental impact of CdTe solar panels, and how is First Solar addressing it?

CdTe panels have a smaller carbon and water footprint compared to silicon, requiring only 1-2% of the semiconductor material. First Solar is also focusing on sustainability by developing a recycling process that recovers over 90% of the materials from used CdTe panels, significantly reducing their environmental impact.

What role does China play in the future of CdTe solar technology?

China, as the world’s largest producer of solar panels, is investing heavily in CdTe technology. Companies like Advanced Solar Power and China National Building Materials are ramping up production with advanced techniques and large-scale manufacturing facilities, which could play a pivotal role in CdTe’s global adoption.

Why hasn’t CdTe solar technology overtaken silicon in the global market yet?

CdTe solar technology lags behind silicon in the global market due to silicon's overwhelming popularity, reliability, and well-established production processes. While CdTe has some advantages, including thinner panels and lower environmental impact, silicon remains the preferred choice for most applications due to its efficiency and market dominance.