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Team SBThe transition to renewable energy sources has become an irreversible trend in the energy sector globally. While the future of solar looks promising among various sources, continuous advancements in panel efficiency are essential to enhancing its competitive edge.
This article will round up different types of mature, higher-efficiency solar panel technologies available on the market, while providing some valuable insights into the technical routes to achieve better results and future development of high-efficiency panels.
Solar Panel Market Overview
Though many challenges remain, the global solar market is still expected to grow by 22% in 2024, reaching a market size of 544 gigawatts (GW), which is approximately 100 GW more than in 2023. This inspiring growth is part of a broader trend, with global photovoltaic installations projected to reach between 2-5 terawatts (TW) by 2030 and 4-15 TW by 2050.
From a technical perspective, since the first practical cell was developed in 1954, solar panel technology has been evolving rapidly with many new architectures and materials emerging.
However, A July 2024 report from Fraunhofer ISE reveals that crystalline silicon (c-Si) based solar photovoltaic technology still remains the market leader, accounting for approximately 97% of global production in 2023, with thin-film technology taking second place.
Within the c-Si segment, mono-crystalline (mono-Si) technology became the dominant technology holding around 99% of the share, while poly-crystalline (poly-Si) technology is being phased out. Notably, in the last decade, the efficiency of commercial mono-Si-based panels has increased from about 16% to 22% and more.
Additionally, evident changes in efficiency-enhancing strategy have been seen in c-Si products. Traditional BSF (Back Surface Field) approach is being replaced. The uptake of newer approaches such as PERC and HJT is on the rise.
Routes to Yield Higher Panel Efficiencies & Production
A series of other methods beyond the mentioned have been adopted by solar manufacturers to improve the efficiency of solar panels since their birth. But with a close examination, actually, they can be categorized into several routes, explained as follows:
Material Innovations
A large portion of solar panel production today has shifted towards mono-Si and n-type technology, replacing traditional poly-Si and p-type approaches. These materials hold the properties to provide higher efficiencies, improved temperature coefficient, lower degradation and enhanced durability and others.
On the other hand, dopants are crucial materials that modify the electrical properties of silicon to create necessary p-n junctions. While boron (B) and phosphorus (P) are commonly used dopants in silicon wafers for solar panels, other dopants such as gallium (Ga) as well as dopant combinations have been used to create high-efficiency panels.
Semiconductor Layer Architectures
While in most cases two c-Si materials with different electrical properties are placed together to form the p-n junction of the cell, manufacturers have been exploring the use of other semiconductor materials to create more superior p-n junctions. One classic example is the heterojunction (HJT) cell, which combines the strengths of both c-Si and a-Si materials and inserts an intrinsic layer to enhance the efficiency of energy conversion. Besides, some companies are integrating perovskite and silicon to create perovskite-silicon tandem cells.
Innovation in architecture is also embodied in the number of junctions implemented.
In contrast to conventional single-junction panels, which feature only one p-n junction, some researchers are exploring the development of multi-junction (usually more than two) panels. Each junction is designed to capture a specific range of wavelengths, playing a dedicated role in overall efficiency.
Enlarged Active Area
The active area of a panel is the area that is responsible for converting and generating electricity, as opposed to the non-active areas such as frame and metal contacts.
By enlarging the active area, the amount of sunlight that the panel receives increases, laying the ground for more power production. Approaches to enlarge the area include minimizing the number of front metal contacts, ‘bifacializing’ the panel, altering the cell arrangement within the panel, and more.
Electrical & Engineering Improvements
Another route to yield better results is through improving the electrical and engineering aspects.
Part of electrical improvements involve conducting new designs to augment power collection and reduce power losses. For example, some manufacturers alter the size of cells to drive down resistive losses. Other major electrical and engineering approaches center on reducing light reflections and surface recombination by employing proprietary coatings and texturing techniques, combining passivation layers, and optimizing other enhancements.
Modern automated production lines, precise laser processing and more aid in meeting premium standards and consistent panel performance.
Rounding up High-Efficiency Commercial Solar Panels on the Market
There is a wide range of the best high-efficiency commercial solar panels available on the market, delivering exceptional results across a broad spectrum of solar projects.
Below is a roundup of them, each with a link to a dedicated explanation of the technology.
PERC Solar Panels
PERC (Passivated Emitter and Rear Contact) technology is a mainstream, cost-effective enhancement to traditional solar panels. These panels incorporate a passivation layer generally composed of aluminum oxide (Al₂O₃) or silicon dioxide (SiO₂) on the rear side of the panel to reflect unabsorbed light back and reduce recombination. This modification leads to higher output and also better performance in low-light conditions.
Half-Cut Solar Panels
More accurately put, they are half-cut cell solar panels.
This technology involves cutting solar cells in half to reduce resistive losses and improve performance. By halving the cells, the current flowing through each cell is reduced, which decreases the resistance and increases the overall efficiency of the solar panel.
Half-cut panels also perform well in shaded conditions because the cells are wired with a configuration combining both series and parallel, allowing parts of the panel to continue generating power even when partially shaded.
IBC Solar Panels
IBC (Interdigitated Back Contact) technology follows the route of enlarging the active area to achieve higher efficiencies.
These panels place all electrical contacts on the rear side, eliminating front-side-grid shading on the front and allowing more sunlight to be absorbed. Meanwhile, they result in an improved aesthetic appearance, being a good choice for projects where efficiency and aesthetics are vital.
TOPCon Solar Panels
TOPCon (Tunnel Oxide Passivated Contact) technology also boosts efficiency by strengthening passivation, but in a more elaborate way. These panels use a super-thin oxide tunnel oxide layer and a high-conductivity poly-Si layer on the rear of the panel to passivate surfaces, allow better carrier flow and reduce recombination.
HJT Solar Panels
HJT (Heterojunction Technology) is the most successful commercial instance to combine the use of different materials to form the semiconductor layer.
By comparison, the amorphous silicon (a-Si) material has a different bandgap than c-Si, allowing it to absorb higher energy photons more efficiently. This hybrid design benefits from the overlapping of absorption capabilities of both materials.
HJT solar panels also have reduced recombination losses, high temperature tolerance as well as good performance in low-light conditions.
Shinged Solar Panels
Shingled solar panels use overlapping strips of cells, which eliminates the need for busbars on the front of the panel. This design reduces shading attributed to front contacts and increases the active area exposed to sunlight, improving efficiency.
Somewhat like the half-cut panels in terms of electrical configuration, shingled panels also offer better performance in partial shading conditions, as the design allows for more flexible wiring.
Prospecting the Future of High-Efficiency Solar Panel Development
The future of high-efficiency solar panel development is promising, with ongoing research to enhance performance and address key challenges in the field.
On one hand, the industry will keep on following the main routes outlined previously to drive innovation, whether by upgrading existing technology or inventing new ones.
Secondly, crossovers or combinations of various advanced solar technologies can lead to significant improvements in solar panel efficiency. Studies indicate that the combination of TOPCon and IBC has shown steady, high efficiencies ranging from 21% and above. While the integration of HJT and shingled can lead to efficiencies above 26%. To name a few.
Final Thoughts
Up until now, one point related to solar panel efficiency is overlooked. No matter how exciting the efficiency figures of the best high-efficiency panels are, they are first the nominal numbers.
To maximize their outputs, project developers should undertake comprehensive and scientific analysis for the site and struggle for an optimal design. We should also be aware that a certain type of high-efficiency solar panel may suit the site better than the others. Furthermore, supporting facilities such as solar tracking and ventilation/cool systems can serve to unlock the full potential of these panels.
