This engineer’s solar panels are breaking efficiency records

The incredulous Chen marveled not only at the technology, but also at the economics. Would the government pay its clients?

It sounded like magic: useful and valuable electricity obtained from ordinary sunlight. The wonder of it all has fueled his dreams ever since.

In 2013, Chen obtained his Ph.D. in photovoltaic science and technology, and is currently deputy vice president of technology at Trina Solar, a Chinese company based in Changzhou, which is one of the largest photovoltaic module manufacturers in the world. He leads the company’s research and development group, whose efforts have set more than twenty world records for solar energy efficiency and performance.

For Chen’s contributions to photovoltaic energy conversion science and technology, he received the 2023 IEEE Fellowship Award IEEE Stuart R. Wenham Award for Young Professionals With IEEE Electron Device Society.

“I was surprised and very grateful” to receive the Wenham Award, Chen says. “This is an award at a very high level, and it includes so many distinguished experts from all over the world.”

Trina Solar strives to create more efficient equipment

Today’s commercial solar panels typically achieve around 20% efficiency: they can convert one-fifth of captured sunlight into electricity. Chen’s group is trying to make the panels more efficient.

The group focuses on optimizing solar cell designs, including the passivated emitter and rear cell (PERC), which is the industry standard for standard solar panels.

Invented in 1983, PERCs are used today in… almost 90 percent of solar panels available on the market. They feature front and back coatings that capture sunlight more effectively and prevent energy loss, both on surfaces and as sunlight travels through the cell. The coatings, called passivation layers, are made of materials such as silicon nitride, silicon dioxide and aluminum oxide. The layers separate negatively charged free electrons from positively charged electron holes, preventing them from combining on the surface of the solar cell and wasting energy.

Chen and his team developed several ways to increase the efficiency of PERC panels: achieving record efficiency of 24.5% in 2022. One technology is a multi-layer anti-reflective coating that helps solar panels retain more light. They also created extremely thin metallization fingers — narrow lines on the surface of solar cells — that collect and transport electrical current and help capture more sunlight. They also developed an advanced method of laying strips of conductive metal running through the solar cell, called busbars.

Experts predict that the maximum efficiency of PERC technology will be reached soon and will be around 25 percent.

IEEE member Yifeng Chen presents the i-TOPCon solar module, which has a production efficiency of more than 23 percent and an output power of up to 720 watts.Trina Solar

“So the question is: How do we increase the efficiency of solar cells?” says Chen.

Over the past few years, he and his group have been working on tunnel oxide passivated contact (TOPCon) technology. The TOPCon cell uses a thin layer of “tunnel oxide” insulating material – usually silicon dioxide – that is applied to the surface of the solar cell. Like the passivation layers in PERC cells, tunnel oxide stops free electrons and electron holes from combining and wasting energy.

In 2022 Trina has created a TOPCon panel with a record efficiency of 25.5%.and two months ago the company announced achieved a record power of 740.6 watts for the mass-produced TOPCon solar module. The latter was the 26th record set by Trina for solar efficiency and performance.

To achieve this record-breaking performance of TOPCon panels, Chen and his team optimized the company’s manufacturing processes, including laser-induced firing, in which a laser heats part of the solar cell and creates bonds between the metal contacts and the silicon wafer. The resulting joints are stronger and better fitting, which increases efficiency.

“We’re constantly trying to improve solutions to keep a little more sunlight out,” Chen says. “A 1-2 percent increase in productivity is a huge achievement. This may seem like a very small increase, but on a large scale these small improvements create a lot of value in terms of economics, sustainability and value to society.”

Chen says that as solar cell efficiency increases and prices drop, he expects solar power to continue to grow globally. China currently leads the world in installed solar power capacity, accounting for about 40 percent of global capacity. According to the 2023 study, the United States is a distant second with 12%. Rystad Energy report. The report predicted that China’s solar power capacity of 500 gigawatts in 2023 will likely exceed 1 terawatt by 2026.

“I’m inspired by using science to create something useful for people, and then I’m motivated by the pursuit of excellence,” says Chen. “We can always learn something new to make that change, improve that piece of technology, and become just a little bit better.”

Trained by solar pioneers

Chen was present Sun Yat-sen University in Guangzhou, China, where he earned a bachelor’s degree in optical science and technology in 2008. He stayed to continue his doctoral studies. in photovoltaic sciences and technologies. His research focused on high-efficiency wafer-based crystalline silicon solar cells. He was his advisor Hui Shen, a leading PV professor and founder of the university’s Institute for Solar Energy Systems. Chen calls him “the first of three very important figures in my scientific career.”

In 2011, Chen spent a year as a Ph.D. student hour Leibniz University of Hannover, in Germany. There he studied under Pietro P. Altermattthe second influential figure in his career.

Altermatt — a prominent expert in silicon solar cells who later became chief scientist at Trina — advised Chen on computational techniques for modeling and analyzing the behavior of 2D and 3D solar cells. Models play a key role in designing solar cells to optimize their performance.

“A 1-2 percent increase in productivity is a huge achievement. This may seem like a very small increase, but on a large scale these small improvements create a lot of value in terms of economics, sustainability and value to society.”

“Dr. Altermatt changed the way I look at things,” says Chen. “In Germany, they really focus on device physics.”

After obtaining his Ph.D., Chen became a technical assistant at Trina, where he met the third extremely influential person in his career: Pierre Verlindena pioneering photovoltaics researcher who was the company’s chief scientist.

At Trina, Chen quickly rose through the ranks in research and development. Since 2023, he has served as the company’s deputy vice president for technology.

IEEE Research Treasure

Chen joined IEEE as a student because he wanted to attend a conference IEEE Photovoltaics Specialists Conferencethe longest running event dedicated to photovoltaics, solar cells and solar energy.

The membership particularly benefited him during his Ph.D. he studies, he says, because he used the so-called IEEE Xplore Digital Library to access archived documents.

“My work was definitely inspired by the articles I found through IEEE,” says Chen. “Additionally, you click and read other works that are not related to your field but are very interesting.

“The publication repository is a treasure. It’s an eye-opener when you see what’s happening inside and outside your industry, with new discoveries being made all the time.