Solar technology is constantly evolving. Pioneers in the industry have contributed a great deal in innovation, advancing what we think we know about solar technology, into so much more!
In this NEW series, we discuss a few of the most interesting topics in solar technology innovation. Be sure to stay tuned to catch all the instalments!
Part 2 – Thin Film Solar Panels
Among the many innovations in the panel manufacturing space, none may be more appealing and visually exciting than thin-film solar panels.
What is a thin-film solar panel?
Thin-film solar panels are a relatively recent development in the solar panel industry.
Owing to their narrow design and the efficient semi-conductor built into their cells, thin-film solar cells are the lightest PV cell you can find while still maintaining strong durability.
How are these type of solar cells actually made?
These solar cells are created by placing the main material between thin sheets of conductive material with a layer of glass on top for protection. The most distinguishing feature of thin-film panels is that they aren’t always made from silicon. They can be made from a variety of materials, including:
1. Cadmium telluride (CdTe)
The most widely used thin-film technology, CdTe holds roughly 50% of the market share for thin-film solar panels. CdTe contains significant amounts of Cadmium – an element with relative toxicity – so this is a factor of consideration. First Solar is the top innovator and seller in this space.
2. Amorphous silicon (a-Si)
The second most popular thin-film option after CdTe, is a-Si. The a-Si panels also use silicon, but they use non-crystalline silicon and are also topped with glass. A-Si is the most similar technology to that of a standard silicon wafer panel. A-Si is a much better option than its counterparts (CdTe, CIGS) in terms of toxicity and durability, but it is less efficient and is typically used for small load requirements like consumer electronics. The quest for scale is always a hindrance for a-Si.
3. Copper Indium Gallium Selenide (CIGS)
Laboratory CIGS cells have reached efficiency highs of 22.4%. However, these performance metrics are not yet possible at scale. The primary manufacturer of CIGS cells was Solyndra (which went bankrupt in 2011). Today, the leader is Solar Frontier. MiaSolé also manufactures CIGS panels in the U.S. and China.
4. Gallium Arsenide (GaAs)
A very expensive technology, GaAs holds a world record 28.9% efficiency for all single-junction solar cells. GaAs is primarily used on spacecraft and is meant for versatile, mass-scale instalments of PV energy in unusual environments.
How can you tell if a panel is thin-film?
Thin-film panels are obviously easy to identify by their thin appearance. These panels are approximately 350 times thinner than those that use silicon wafers. However, note that thin-film frames can be large sometimes, making the appearance of the entire solar system comparable to that of a monocrystalline or polycrystalline system. Thin-film cells can be black or blue, depending on the material they were made from.
How does silicon compare to thin film?
Crystalline silicon technology has been around for some time and has proven to be valuable. Thin film technology is still in its infancy, but it has the potential to achieve lower costs under the same efficiency and reliability.
1. Crystalline silicon
Advantages:
- High conversion efficiency (reaching 12%-24.2%)
- High stability
- Easy manufacturing
- High reliability
- Heat resistance
- Low installation costs
- More environmentally friendly, considering the time of disposal/recycling
- Well established track record (Crystalline silicon modules have been in production in the 1970s, and monocrystalline silicon panels can withstand harsh environments and can be used for space flight)
Disadvantages:
- In terms of initial cost, crystalline silicon is the most expensive solar module
- The solar energy absorption factor is very low
- The material is brittle and fragile
2. Thin-film solar cells
Advantages:
- Cheaper than old-fashioned crystalline silicon solar cells
- Can be prepared on thin silicon wafers
- More flexible and easier to handle
- Less easily damaged by external shocks
Disadvantages:
- Thin-film solar cell modules have a low efficiency, which can offset its price advantage in some applications.
- Its structure is also more complex
- Flexible thin-film batteries require special installation skills, so they cannot be used in aerospace at present
Resources
1. WATCH a video on Solar Panels
2. LEARN more about Solar Panels
3. CHAT to our solar experts about a clean energy solution for your home, factory or office
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