Understanding CIGS Solar Cell Efficiency: A Guide to Thin-Film Solar Power
What Is CIGS Solar Cell Efficiency?
CIGS solar cell efficiency describes how effectively a CIGS photovoltaic cell converts sunlight into usable electrical energy. CIGS stands for Copper Indium Gallium Selenide, a thin-film semiconductor material used to manufacture solar cells and modules.
CIGS is one of the important thin-film solar panel technologies and has attracted considerable interest because it can combine good conversion efficiency with a very thin absorber layer. CIGS can also be deposited onto different substrates, including glass, metal foils and polymers, which opens up possibilities for lightweight and flexible solar products. NLR
Unlike conventional crystalline silicon solar panels, CIGS does not require a thick silicon wafer to absorb sunlight. The CIGS absorber has a high absorption coefficient, meaning a relatively thin layer can absorb a significant amount of incoming solar radiation. ScienceDirect
This combination of thin-film construction, material efficiency and flexible manufacturing possibilities is what makes CIGS an interesting solar technology for applications where conventional rigid panels may not always be suitable.
What Are CIGS Thin-Film Solar Cells?
CIGS thin-film solar cells are photovoltaic cells manufactured using a semiconductor compound made primarily from copper, indium, gallium and selenium.
The proportions of the materials can be adjusted during manufacture, allowing the electrical properties of the absorber material to be controlled. In particular, changing the ratio of gallium to indium can influence the material’s bandgap and therefore its photovoltaic characteristics. Wiley Online Library
A CIGS solar cell consists of several extremely thin layers rather than a single piece of photovoltaic material. Each layer performs a particular job in the process of converting sunlight into electricity.
The basic principle is straightforward. Sunlight enters the front of the cell, the CIGS absorber captures photons and creates electrical charge carriers, and the cell’s different semiconductor and conductive layers help separate and collect those charges.
CIGS Solar Cell Structure
A typical CIGS cell uses a layered structure consisting of a substrate, conductive back contact, CIGS absorber, buffer layer and transparent conductive layers. The exact construction can vary depending on the manufacturer and production process. ScienceDirect
The main layers include:
- Substrate – Provides the physical foundation for the cell. Glass is commonly used, while metal foils and polymers can also be used for lightweight or flexible designs.
- Molybdenum back contact – Provides the electrical rear contact for the cell.
- CIGS absorber layer – The key photovoltaic layer where sunlight is absorbed and electrical charge carriers are generated.
- Buffer layer – Helps create the required semiconductor junction and assists charge separation.
- Transparent conductive oxide – Allows incoming light to reach the active layers while providing electrical conductivity.
- Front electrical contacts and coatings – Help collect current and can be used to improve the optical and electrical performance of the finished device.
This layered construction is central to the operation of CIGS thin-film solar panels.
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Why Does CIGS Need Such a Thin Absorber Layer?
One of the interesting characteristics of CIGS is its strong absorption of sunlight. Research indicates that a CIGS absorber can be only around 1.5–2 micrometres thick in typical cell designs, although the exact thickness depends on the manufacturing process and device structure. ScienceDirect
That is extremely thin compared with the overall thickness of a conventional framed solar panel.
This helps explain why CIGS can be manufactured as a thin-film technology and, with suitable substrates and encapsulation, can be used in lightweight or flexible solar products.
How Efficient Are CIGS Solar Cells?
When discussing CIGS solar cell efficiency, it is important to distinguish between laboratory research cells and commercial solar modules.
Laboratory CIGS cells have achieved efficiencies above 23%. The 2026 Solar Cell Efficiency Tables report a confirmed CIGS cell efficiency of 23.35% for a cadmium-free cell. DOI.org
Commercial module efficiency is lower than the very best laboratory cell results. This is normal across photovoltaic technologies because manufacturing large-area modules introduces additional electrical, material and production challenges.
Recent research has reported CIGS commercial module efficiencies around the high-teens, demonstrating that CIGS has progressed considerably beyond the older commercial efficiency figures sometimes quoted online. Nature
Therefore, it is better to avoid giving one fixed efficiency figure for all CIGS panels. The actual specification depends on the particular product, manufacturer, module design and generation of technology.
Factors That Influence CIGS Solar Cell Efficiency
Several factors influence the efficiency achieved by a CIGS cell or module.
Bandgap and Material Composition
CIGS has a useful characteristic that its bandgap can be adjusted by changing the composition of the absorber material.
The ratio of indium to gallium influences the bandgap, allowing manufacturers and researchers to optimise the material for photovoltaic performance. Wiley Online Library
Light Absorption
CIGS has a high absorption coefficient, allowing the active absorber layer to remain very thin while still absorbing a substantial proportion of the usable solar spectrum.
This is one of the fundamental reasons CIGS is suitable for thin-film photovoltaic technology.
Temperature
Solar panel performance changes with temperature, and CIGS has attracted interest because of its behaviour at higher operating temperatures.
Research comparing CIGS with crystalline silicon has found that CIGS can perform particularly well relative to silicon under some high-irradiance and high-temperature conditions. However, performance varies with operating conditions and CIGS should not simply be described as superior in every environment. PMC
Manufacturing Quality
The quality and consistency of the different thin-film layers are extremely important.
Small variations in composition, interfaces, defects and manufacturing conditions can affect the voltage, current and overall efficiency of a CIGS device. This is one reason why laboratory record efficiencies cannot simply be applied to every commercial CIGS panel.
CIGS Thin-Film Solar Panels Compared with Silicon
Crystalline silicon remains the dominant photovoltaic technology, particularly for conventional rooftop and ground-mounted solar installations.
Silicon modules can achieve very high commercial efficiencies, while CIGS offers different advantages related to thin-film construction, material use and the ability to manufacture cells on alternative substrates.
The comparison is therefore about more than efficiency alone.
CIGS Advantages
CIGS can offer:
- Thin-film construction
- High sunlight absorption
- Potential for lightweight module designs
- Compatibility with flexible substrates
- Good performance at elevated temperatures in certain conditions
- Adjustable semiconductor properties
- Potential applications where conventional rigid panels are unsuitable
Silicon Advantages
Crystalline silicon can offer:
- Very high commercial module efficiency
- Extensive manufacturing capacity
- A mature global supply chain
- Wide availability
- Large numbers of established installation systems
- Extensive long-term field experience
For this reason, the right solar technology depends on the application rather than simply choosing the technology with the highest laboratory efficiency.
CIGS Compared with Other Thin-Film Solar Panels
CIGS is one of several thin-film photovoltaic technologies.
Other important thin-film technologies include cadmium telluride (CdTe) and amorphous silicon (a-Si).
CIGS has demonstrated higher efficiency than many traditional thin-film technologies, although efficiency varies considerably between manufacturers, products and generations of technology.
CdTe is an established commercial technology used extensively in large-scale solar generation, while amorphous silicon has historically been used for applications where thin and lightweight photovoltaic devices are useful.
CIGS is particularly interesting because it combines thin-film characteristics with the potential for relatively high conversion efficiency.
How Are CIGS Thin-Film Solar Cells Manufactured?
Manufacturing CIGS solar cells involves depositing several extremely thin layers onto a suitable substrate.
Although manufacturing methods vary, a typical process includes several important stages.
Preparing the Substrate
The substrate is prepared and cleaned before the photovoltaic layers are deposited.
Depending on the design, this may be glass, metal foil or another suitable material.
Applying the Back Contact
A conductive back contact, commonly molybdenum, is deposited onto the substrate.
This layer provides an electrical pathway for collecting charge from the CIGS absorber.
Creating the CIGS Absorber
The CIGS absorber is then manufactured using carefully controlled deposition processes.
Different industrial and research approaches can be used, including co-evaporation and sputtering followed by suitable processing. The objective is to produce a CIGS layer with the correct composition, structure and electrical properties.
Adding the Buffer and Front Layers
A buffer layer and transparent conductive layers are subsequently added.
These layers form the required photovoltaic junction and provide a route for electrical current while allowing sunlight to reach the absorber.
The precise manufacturing sequence and materials can differ between CIGS manufacturers.
What Are the Advantages of CIGS Thin-Film Solar Panels?
CIGS technology has several characteristics that make it attractive for specialist photovoltaic applications.
Lightweight Potential
CIGS can be manufactured on lightweight substrates, including metal foils and polymers.
This creates opportunities for applications where reducing the weight of the photovoltaic system is important. NLR
Flexible Solar Applications
When deposited onto suitable flexible substrates, CIGS can be incorporated into flexible photovoltaic products.
This opens possibilities beyond conventional framed glass solar panels, including building-integrated and specialist mobile applications.
Efficient Use of Absorber Material
Because CIGS absorbs sunlight strongly, only a relatively thin absorber layer is required.
This is one of the defining characteristics of thin-film photovoltaic technology.
High Research Efficiency
CIGS has demonstrated impressive laboratory efficiencies, with confirmed research-cell results exceeding 23%. DOI.org
That does not mean every commercial CIGS panel will achieve this efficiency, but it demonstrates the potential of the underlying technology.
What Are the Challenges of CIGS Solar Technology?
CIGS is not without challenges.
Material Availability
CIGS uses elements including indium and gallium, which are not as abundant as some of the materials used in conventional silicon photovoltaic technology.
Material availability and cost therefore remain considerations for large-scale manufacturing.
Manufacturing Complexity
Producing high-quality CIGS layers requires carefully controlled manufacturing processes.
The composition, thickness, interfaces and electrical properties of the layers all affect the final performance of the solar cell.
Cadmium in Some Designs
Some traditional CIGS cell structures use cadmium sulfide as a buffer layer.
Research and commercial development have also investigated cadmium-free alternatives, and confirmed efficiency records include cadmium-free CIGS cells. DOI.org
Therefore, it is important to look at the specific construction of a CIGS product rather than assuming that every CIGS panel uses exactly the same materials.
CIGS Solar Cell Efficiency in Real-World Conditions
A laboratory efficiency figure is useful for understanding the potential of a technology, but it does not tell the whole story about how a solar panel will perform in everyday use.
Solar modules operate under constantly changing conditions. Irradiance, temperature, shading, orientation, spectrum and system design can all affect energy production.
Research comparing CIGS with crystalline silicon has found that the relative performance can change significantly depending on temperature and irradiance. In particular, CIGS can have advantages under some high-temperature, high-irradiance conditions, while crystalline silicon can perform better under some low-irradiance conditions. PMC
This is why annual energy yield and the actual installation environment are often more useful measures than headline efficiency alone.
The Future of CIGS Thin-Film Solar Technology
Research into CIGS thin-film solar cells continues to focus on improving efficiency, reducing manufacturing costs, increasing reliability and developing new applications.
One particularly interesting area is the use of flexible substrates. CIGS can be deposited onto metal foils and polymers, allowing photovoltaic technology to be used in situations where conventional glass-based modules are impractical. NLR
Researchers are also investigating improved absorber compositions, surface treatments, defect control and alternative buffer layers.
The continuing development of CIGS demonstrates that solar technology is about much more than conventional rigid silicon panels.
Frequently Asked Questions About CIGS Solar Cells
What does CIGS stand for?
CIGS stands for Copper Indium Gallium Selenide. It is a semiconductor material used as the absorber layer in a type of thin-film solar cell.
Are CIGS solar cells efficient?
Yes. Laboratory CIGS cells have achieved efficiencies above 23%, while commercial module efficiencies are generally lower. The efficiency of an individual product depends on its design, manufacturer and technology generation. DOI.org
Are CIGS solar panels better than silicon?
CIGS and silicon have different characteristics. Silicon generally offers higher commercial efficiencies, while CIGS can provide advantages in thin-film construction, lightweight designs and flexible applications.
Can CIGS solar panels be flexible?
Yes. CIGS photovoltaic material can be deposited onto flexible substrates such as metal foils and polymers, allowing flexible module designs. NLR
Do CIGS panels work well in hot weather?
CIGS can perform particularly well relative to crystalline silicon under some high-temperature conditions. However, actual performance depends on irradiance, temperature, module construction and the wider system. PMC
Are CIGS solar panels thin-film panels?
Yes. CIGS is one of the established thin-film photovoltaic technologies.
Conclusion: Understanding CIGS Solar Cell Efficiency
CIGS solar cell efficiency is only one part of what makes CIGS technology interesting. Its combination of strong light absorption, thin-film construction, adjustable material properties and compatibility with flexible substrates gives it characteristics that are different from conventional crystalline silicon solar panels.
Laboratory research has demonstrated CIGS efficiencies above 23%, while commercial modules operate at lower efficiencies depending on the particular product and manufacturing technology. DOI.org
For anyone interested in solar technology, CIGS is an excellent example of how photovoltaic research is moving beyond traditional rigid silicon panels. Its potential for lightweight and flexible applications could make it particularly useful in specialist solar installations where conventional panels are not always practical.