Conventional solar panels are made of silicon in crystalline form, known as c-Si. Unlike thin-film panels, traditional panels have photovoltaic cells cut from silicon wafers of single crystals (monocrystalline) or multiple crystals (polycrystalline). Thin-film panels are made of whole layers of PV material, not small silicon cells.
You can classify thin-film solar panels based on the material. The four main types include:
- Amorphous silicon (a-Si)
- Cadmium telluride (CdTe)
- Copper indium gallium selenide or diselenide (CIGS)
- Organic photovoltaic (OPV)
Amorphous Silicon Panels
Amorphous silicon (a-Si) panels use the same material as traditional photovoltaic cells. But with thin-film panels, the silicon has a non-crystalline or “amorphous” structure. These panels use less silicon than traditional solar modules and, as a result, are more affordable. Amorphous silicon panels were the first thin-film PV technology to be developed. You can find the technology used in older calculators and other small gadgets.
Amorphous silicon panels have a typical energy conversion efficiency of 6% to 8%, while the best crystalline silicon panels approach 23% efficiency.
Pros and Cons
+ Lightweight and affordable
+ Uses non-toxic materials
+ Can have a rigid or flexible design
– Low energy efficiency
– Rapid efficiency loss after installation
– Shorter lifespan than crystalline silicon panels
Cadmium Telluride Panels
Cadmium telluride (CdTe) panels are more efficient than amorphous silicon panels, ranging from 9% to 15%. They are the most popular panels in the thin-film solar industry, representing around half of the global market share. First Solar is one of the leading manufacturers of CdTe panels, having invested over $1.5 billion to develop this solar technology.
The main downside of CdTe panels is the use of cadmium, a highly toxic metal. Cadmium does not represent a risk when the panels are generating electricity. However, it can be a risk for factory workers exposed during manufacturing, and disposal is a problem.
Pros and Cons
+ Higher efficiency than amorphous silicon panels
+ Low manufacturing and installation costs
+ Shorter payback period than other thin-film panels
– Uses Cadmium, which is a toxic metal
– Less efficient than crystalline silicon panels
– Flexible CdTe panels can be hard to find
Copper Indium Gallium Diselenide Panels
Copper indium gallium diselenide (CIGS) panels use different semiconductor materials that are arranged in layers. CIGS panels have a typical efficiency of 12% to 14%, comparable to the performance of CdTe panels. CIGS technology is also compatible with multiple materials such as steel, aluminum, glass and plastics.
The main drawback of CIGS thin-film panels is their high production cost, which results in a longer payback period. Some CIGS panels also use cadmium, creating the same environmental issues as CdTe panels. However, manufacturers are replacing cadmium with zinc oxides, which are much safer materials.
Pros and Cons
+ Higher efficiency than amorphous silicon panels
+ Compatible with multiple materials and surfaces
+ Rigid and flexible panels are available
– More expensive than other thin-film panels
– Many CIGS modules contain cadmium
– Longer payback period than other thin-film panels
Organic Photovoltaic Panels
Organic photovoltaic (OPV) panels use polymers and other organic materials with photovoltaic properties to produce energy. OPV panels have an efficiency of around 11%, which is higher than the efficiency of a-Si panels. However, OPV panels feature lower efficiency ratings than CdTe and CIGS panels.
Since organic materials are abundant and inexpensive, OPV panels are very affordable. But organic photovoltaic materials are less durable than the inorganic compounds used in other thin-film technologies.
Pros and Cons
+ Low-cost manufacturing process
+ Available in many colors due to the variability of absorbers
+ Organic PV materials are abundant and safe
– Lower efficiency than most PV technologies
– Shorter lifespan than inorganic solar cells
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