This Engineer’s Solar Panels Are Breaking Efficiency Records

An incredulous Chen marveled at not only the technology but also the economics. A power authority would pay its customers?

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

In 2013 Chen earned a Ph.D. in photovoltaic sciences and technologies, and today he’s assistant vice president of technology at China’s Trina Solar, a Changzhou-based company that is one of the largest PV manufacturers in the world. He leads the company’s R&D group, whose efforts have set more than two dozen world records for solar power efficiency and output.

For Chen’s contributions to the science and technology of photovoltaic energy conversion, the IEEE member received the 2023 IEEE Stuart R. Wenham Young Professional Award from the IEEE Electron Devices Society.

“I was quite surprised and so grateful” to receive the Wenham Award, Chen says. “It’s a very high-level recognition, and there are so many deserving experts from around the world.”

Trina Solar’s push for more efficient hardware

Today’s commercial solar panels typically achieve about 20 percent efficiency: They can turn one-fifth of captured sunlight into electricity. Chen’s group is trying to make the panels more efficient.

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

Invented in 1983, PERCs are used today in nearly 90 percent of solar panels on the market. They incorporate coatings on the front and back to capture sunlight more effectively and to avoid losing energy, both at the surfaces and as the sunlight travels through the cell. The coatings, known as passivation layers, are made from materials such as silicon nitride, silicon dioxide, and aluminum oxide. The layers keep negatively charged free electrons and positively charged electron holes apart, preventing them from combining at the surface of the solar cell and wasting energy.

Chen and his team have developed several ways to boost the performance of PERC panels, hitting a record of 24.5 percent efficiency in 2022. One of the technologies is a multilayer antireflective coating that helps solar panels trap more light. They also created extremely fine metallization fingers—narrow lines on solar cells’ surfaces—to collect and transport the electric current and help capture more sunlight. And they developed an advanced method for laying the strips of conductive metal that run across the solar cell, known as bus bars.

Experts predict the maximum efficiency of PERC technology will be reached soon, topping out at about 25 percent.

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

“So the question is: How do we get solar cells even more efficient?” Chen says.

During the past few years he and his group have been working on tunnel oxide passivated contact (TOPCon) technology. A TOPCon cell uses a thin layer of “tunneling oxide” insulating material—typically silicon dioxide—which is applied to the solar cell’s surface. Similar to the passivation layers on PERC cells, the tunnel oxide stops free electrons and electron holes from combining and wasting energy.

In 2022 Trina created a TOPCon-type panel with a record 25.5 percent efficiency, and two months ago the company announced it had achieved a record 740.6 watts for a mass-produced TOPCon solar module. The latter was the 26th record Trina set for solar power–related efficiencies and outputs.

To achieve that record-breaking performance for their 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 connections are stronger and better aligned, enhancing efficiency.

“We’re trying to keep improving things to trap just a little bit more sunlight,” Chen says. “Gaining 1 or 2 percent more efficiency is huge. These may sound like very tiny increases, but at scale these small…