Thin-film Solar Panels

By: Mawin Nicole M. Reyes

[This is the third blog post of our three-part series on Types of Solar PV Panels]

Originally introduced in the 1970s by researchers from the Institute of Energy Conversion at the University of Delaware in the United States, thin-film solar panels are designed to convert light energy to electrical energy via the photovoltaic effect. This type of cell is composed of a thin-film solar panel made up of micron-thick photon-absorbing layers of material deposited over a flexible substrate such as glass, plastic, or metal in a chemical process called vapor deposition [1][2].

The materials selected for deposition determine the type of thin-film solar cell. These materials must be suitable for deposition over large substrate areas of up to 1m to allow high-volume manufacturing. As such, materials used for deposition are strong light absorbers such as amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium (gallium diselenide (CIS or CIGS) [2]. It is important to note that at high temperatures, the a-Si and CdTe array losses are higher—reaching losses up to 2.83 h/day, while that of CIGS-based pc-Si thin-film solar cells appears to be more stable with average array capture losses of 7.41 (kWh/kWp)/month and 10.4 (kWh/kWp)/month, respectively. Such results show that pc-Si and CIGS modules can perform a high annual energy yield [4]. On the other hand. seasonal changes affect inverter efficiency in the system such that during summer, the efficiency reaches up to 98%, dropping to as low as 30% during winter. [4].

Commercially, amorphous silicon thin-film solar cells cost less than CdTe or CIS thin-film cells [2]. This type of thin-film solar cell is also flexible and has a wide array of applications. In fact, during the 1980s, thin-film solar cells were used for calculators and watches; their usage increased in the early 21st century, with a-Si-based being often used in consumer electronics [4]. Thin-film solar cells are also gaining popularity, especially for the ease of their installation on curved surfaces and building-integrated photovoltaics [1]. However, for the residential sector, thin-film solar cells are advisable only for homes with adequate roof space that can “benefit from an economies-of-scale installation as well as the aesthetic benefits of the frameless and glass-on-glass thin-film models that are commonly offered by the leading manufacturers” [4].

However, thin-film solar panels tend to have a lower efficiency level and can take up a lot more space than their crystalline counterparts, making them the cheapest option with plenty of potential for future innovations. This is especially true for home or commercial building purposes. Some advantages of thin-film solar cells induce their flexibility, allowing for a wide range of small or large applications. The ease of mass manufacturing of this type of solar cell makes it cheaper to produce. Its shading has a similar effect on its efficiency, such that high temperatures and shading have less impact. Its homogenous and often black appearance makes them look aesthetically pleasing, and thin-film solar cells also tend to be lighter than crystalline cells. On the other hand, thin-film solar cells may not be conducive for domestic use since they can take up a lot of space and have low efficiency and less durability—which can incur further costs for enhancements, maintenance, and supports, they also tend to have shorter lifespans and shorter warranty periods when bought [3].

References:

[1] Burgess, D. (2014, November 21). Thin-film solar cell | Definition, Types, & Facts | Britannica. Britannica. https://www.britannica.com/technology/thin-film-solar-cell

[2] Mercaldo, L. V., Addonizio, M. L., Noce, M. D., Veneri, P. D., Scognamiglio, A., & Privato, C. (2009). Thin film silicon photovoltaics: Architectural perspectives and technological issues. Applied Energy, 86(10), 1836–1844. https://doi.org/10.1016/j.apenergy.2008.11.034

[3] The Renewable Energy Hub. (2020, March 31). Thin Film Solar Panels. The Renewable Energy Hub. https://www.renewableenergyhub.co.uk/main/solar-panels/thin-film-solar-panels/

[4] Zdyb, A., & Gulkowski, S. (2020). Performance Assessment of Four Different Photovoltaic Technologies in Poland. Energies, 13(1), Article 1. https://doi.org/10.3390/en13010196

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