With PERC (Passive Emitter and Rear Contact) technology, light that has already passed through the silicon cell structure is reflected into the cell to produce extra power. This boosts the efficiency of solar cells and panels.
The University of New South Wales in Sydney created this technique in the late 1980s and early 1990s, and most solar panel producers worldwide have since embraced it.
PERC technology boosts high-temperature performance, reduces electron recombination, and increases efficiency by reflecting light back into the cell structure. As a result, it became the primary cell technology in the solar industry towards the beginning of the 2020s.
What is unique about a solar panel that uses PERC technology?
Solar power has undergone significant advancements in the past decade. Passivated Emitter and Rear Cell (PERC) technology is one of the leading innovations. Particularly in China, PERC has become a central feature in solar panels and has been the dominant cell technology since the early 2020s.
PERC involves adding a special layer to the back of a solar cell, reducing electron loss. It has been used mainly with P-type mono-crystalline panels globally over recent years. The technology increases the efficiency of solar cells and panels by reflecting light that has passed through the silicon cell structure back into the cell. This increases the solar panel’s efficiency and produces more power per square meter of panel surface.
The original PERC technology was developed by the University of New South Wales in Sydney in the late 1980s. Dr Martin Green and his colleagues at UNSW were exploring ways to enhance solar cells. By 1989, they unveiled the PERC technology, revolutionising the field. But like so many Australian inventions, from the Black Box flight recorder to Wifi, the technology was sold to overseas manufacturers.
Initially European manufacturers, including Qcells and REC, further developed the idea and technology. The technology was first used in the manufacture of solar cells in 2012 by Qcells and expanded from there. Most manufacturers worldwide now use the PERC technology within their solar cells.
How does it compare to previous cell technology?
Firstly, the solar cell creates electricity when light passes through the silicon cell structure. The light pushes electrons out of their current position, creating an electric current. The more efficiently this process occurs, the more electricity the cell will generate.
Before PERC, manufacturers used the traditional standard cell technology called the Backside Field (BSF) structure on the back of the crystalline solar cells. In this method, they applied an aluminium paste/surface to the back area of the solar cell. As a result, some light that passes through the cell structure hits the rear surface and then the cell utilizes it to generate electricity.
The basic structure of the solar cell has not changed. It still includes a silicon solar cell with conductive fingers and busbars on the front surface of the cell. Scientists created the PERC cell to use this light within the cell more efficiently.
By adding a reflective layer at the back of the cell (and texturing this surface), the design can reflect light that initially passes through the cell back into the cell structure for a second chance to create more power. This addition creates a bounce effect.
So the key difference between the traditional solar cell and the PERC solar cell lies in the addition of a reflective layer on the back of the cell. Therefore, at a relatively low cost, it can generate more electricity.
The PERC structure increases the efficiency of the cell
1. Light reflection back into the cell structure creates more electricity. This is particularly effective in low light conditions such as early morning and late afternoon, where the low angle of light from the sun increases the light reflected off the cell’s rear.
2. Through improved high temp performance. The traditional cell structure, where the excess light is absorbed by the BSF (Back Surface Field) layer on the back of the cell, sees the absorbed light energy converted to heat, which reduces the cell performance.
By reflecting the light into the cell and creating more electricity, the PERC structure reduces the heating effect and therefore increases the cell’s performance.
3. Reduced electron recombination. One of the expected efficiency losses in solar cells is electron recombination, where the moving electron “recombines” into its default cell position, reducing the flow of electrons and therefore generating electricity.
The PERC structure reduces electron recombination and generates more consistent electricity. For all these reasons, PERC technology has become the leading technology in today’s solar panels.
China’s adoption and expansion of PERC
China’s rigorous commitment to renewable energy provided the perfect environment for PERC technology to flourish. Below are the reasons for its phenomenal success, especially in China:
1. Government support and regulations
China’s focus on cutting carbon emissions and lowering dependence on non-renewable energy led to significant investments in solar innovations like PERC, supported by central and local governmental policies.
2. Economic efficiency
PERC panels deliver greater efficiency without a corresponding increase in production cost. This appealed to Chinese manufacturers striving to produce top-tier solar panels at competitive rates. Its relatively simple and low-cost implementation also went hand in hand with the Chinese goal to increase production capacity aggressively. This massive expansion by manufacturers such as Jinko, Trina, JA and Longi created significant volume-based cost reductions for panels. Non-Chinese competitors without Government support found it difficult to compete and follow these expansion curves.
3. International cooperation
China’s alliances and sponsorship of global research institutions and technology firms facilitated knowledge transfer and mastery of PERC technology.
4. Global demand
The worldwide demand for cheap renewable energy matched in timing China’s decision to expand production and incorporate PERC technology, maintaining and later expanding its lead in solar panel production.
Chinese PERC panels are now benchmarks for both efficiency and affordability, leading to enhanced exports and reinforcing China’s standing as a renewable energy powerhouse.
PERC technology, pioneered by Dr. Martin Green and his UNSW team, marked a milestone in photovoltaic development. Its widespread use in Chinese solar panels showcases China’s aspiration to lead the global renewable energy arena.
The tale of PERC’s creation and its integration into Chinese solar panels isn’t just a technological marvel but an illustration of international collaboration, innovation driven by policy, and the drive for efficiency. As the global community continues to pursue sustainable energy, innovations like PERC represent the strides possible through creative thinking and global teamwork.