Have you ever come across “flexible solar panels,” or “stick-on solar panels”? Both fit under the wider umbrella of thin-film solar panels, which is a type of solar panel technology known for being lightweight. Compared to traditional solar panel cells, thin-film solar panels are made up of electricity-producing layers that are hundreds of times thinner than typical silicon cells.
There are many different types of thin-film panels, built using a variety of materials and processes. In this article, we’ll review the four major types of thin-film solar panels, and what sets them apart from other thin-film options: amorphous, cadmium telluride (CdTe), copper gallium indium diselenide (CIGS), and organic solar panels.
Amorphous solar panels
Like conventional solar panels, amorphous solar panels are primarily made up of silicon. However, though built with the same material, they are constructed in a different way: instead of using solid silicon wafers (like you do with mono- or poly-crystalline solar panels), manufacturers make amorphous panels by depositing non-crystalline silicon on a substrate of glass, plastic, or metal. One layer of silicon on an amorphous solar panel can be as thin as one micrometer – to put that into perspective, that’s thinner than a human hair!
Advantages and disadvantages of amorphous solar panels
Amorphous solar panels have many advantages over their solar panel counterparts. For one, companies don’t need to use a lot of toxic materials to build amorphous silicon panels – this is not always true with some other types of panels. Additionally, they require much less silicon than conventional solar panels. Amorphous solar panels are also bendable, and less susceptible to cracks than traditional panels constructed from solid wafers of silicon.
However, there are also some disadvantages to amorphous solar panel technology, the primary challenge being their efficiency: compared to conventional silicon solar cells, amorphous solar cells are typically less than half as efficient. Most types of amorphous solar panels hover around 7 percent efficiency, while mono- or poly-crystalline solar panels on the market today can have efficiencies of over 20 percent.
Cadmium telluride (CdTe) solar panels
Cadmium telluride (CdTe) panels are the most popular type of thin-film solar technology used in installations today. These panels are made up of several thin layers: one main energy-producing layer made from the compound cadmium telluride, and surrounding layers for electricity conduction and collection. One of the most well-known manufacturers of CdTe panels is First Solar, an American company headquartered in Tempe, Arizona.
Advantages and disadvantages of cadmium telluride solar panels
One of the most exciting benefits of CdTe panels is their ability to absorb sunlight close to an ideal wavelength, or shorter wavelengths than are possible with traditional silicon solar cells. Simply put, shorter wavelengths mean higher energy, which is easier to convert to electricity. Plus, cadmium telluride panels cost less to manufacture and install than other types of solar panels.
However, one of the biggest concerns with CdTe panels is pollution. Cadmium is a toxic heavy metal – one of the most potent ones at that. Cadmium telluride, the compound used in these panels, also has some toxic properties. Importantly, CdTe panels are not harmful to humans or the environment as they generate electricity on rooftops, and companies take proper health precautions when handling the materials during the manufacturing process. However, the disposal of old CdTe panels continues to be a concern.
Also, like amorphous panels, cadmium telluride panels come in at lower efficiencies than other types of solar panels. Sitting around 10 to 11 percent, CdTe panels are above the efficiencies of amorphous panels, but still don’t come close to the average efficiencies of standard silicon panels.
Copper gallium indium diselenide (CIGS) solar panels
CIGS solar cells are made from a compound called copper gallium indium diselenide (try saying that five times fast!) sandwiched between conductive layers. This material goes on top of different types of layers, such as glass, plastic, steel, and aluminum. Some types of CIGS panels use a flexible backing, and the thin layers allow for full-panel flexibility.
Advantages and disadvantages of CIGS solar panels
Unlike most other thin-film solar technologies, CIGS solar panels offer competitive efficiencies to traditional silicon panels. With efficiencies exceeding 20 percent in laboratory tests, there may be a place for high-efficiency CIGS panels in the global solar panel market.
Like CdTe panels, many CIGS cells also use the toxic chemical cadmium. However, CIGS technologies use a lower percentage of cadmium, and therefore are a more environmentally-friendly choice as far as thin-film solutions go – even better, some models exchange the use of cadmium for zinc.
The biggest disadvantage of CIGS panels is their price. While CIGS solar panels are an exciting technology, they remain very expensive to produce, to the point where they have a hard time competing against the more economical silicon or CdTe panels.
Organic photovoltaic cells
Organic photovoltaic (OPV) cells use conductive organic polymers or small organic molecules to produce electricity. In an organic photovoltaic cell, several layers of thin organic vapor or solution are deposited and held between two electrodes to carry an electrical current.
Advantages and disadvantages of organic PV cells
OPV cells are most popular among the building-integrated photovoltaic (BIPV) market. Because you can use different types of absorbers in an organic cell, OPV devices come in a variety of colors (and can even be transparent!) This aesthetic advantage makes OPV a popular option for unique BIPV applications. Plus, the materials companies need to build organic solar cells are abundant, leading to low manufacturing costs and subsequently low market prices.
Unfortunately, like other thin-film options, organic photovoltaic cells currently operate at relatively low efficiencies. OPVs typically have efficiency ratings of about11 percent, but scaling module production up while keeping efficiencies high is a problem for the technology. Much of the research currently surrounding OPVs is focused on boosting its efficiency.
Another disadvantage of OPV technology is its lifespan: this tech has a shorter lifespan than both traditional panels and other thin-film options. Cell degradation that doesn’t occur in inorganic modules is an ongoing struggle for organically-based photovoltaic products.
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