Why Should PV Installers Care about Solar Cell Efficiency?

LONGi solar cells

Many solar installers take for granted that the modules they buy for their residential and commercial projects will continue to increase in power rating and include new design innovations, such as glass-glass construction and module-level power electronics. The solar industry has excelled at innovation, especially over the past few years with the introduction of monocystalline PERC and bifacial PERC cell technologies, large-format modules for the utility-scale sector, multibusbar and split-cell architectures, and the other improvements.

But how many installers really dig deeper into why their panels keep getting better, and why should they care?

Installers who’ve been in business for a decade or so remember when they were installing 250-watt modules on the roof and then 320s a few years later. These same installers now benefit from modules in the 400-450 watt class—that’s a 60%-plus boost in less than 10 years. To put it design terms: it takes 10 or fewer modules to outfit that “simple” 4-kW rooftop system that needed 16 modules a decade ago. The benefits include more bang for the buck, more power density, lower racking or other balance of systems costs—and quicker installation times.

How does this relentless power rating progress come about? Certainly, the module-level innovation mentioned previously has played a role, but the single most important determining factor to the higher wattages and lower levelized cost of energy (LCOE) is solar cell conversion efficiency.

Over the past couple of years, large-format modules using M6 (166mm) and M10 (182mm) wafers have been an effective approach to improving module power and reducing balance of systems (BOS) cost. However, further increasing module dimensions with higher power brings little BOS savings, while reliability risks jump up significantly. In the next few years, we need to refocus on cell and module efficiency improvement to realize lower and lower LCOE.

Solar cell efficiency is where the rubber meets the road. Making cells is arguably the most important part of the solar manufacturing chain, a complicated semiconductor process involving a series of microprocessing steps done on production lines in impressive, automated factories turning out tens of thousands of cells per hour. By optimizing processes such as deposition, passivation and doping and innovating new cell materials and designs, technologists can squeeze more and more efficiency out of the cells—which results in higher wattage modules.

At a recent conference, I discussed several aspects of technology leadership for the terawatt era, with a heavy focus on R&D and cell innovation. LONGi spends more on R&D than any other solar company; in fact, we invested about $1.9 billion between 2012 and 2021, significantly more than any of our peers—including $689 million in fiscal 2021 alone. What these investments mean is that we can develop, manufacture and supply high-performance products at a lower cost all while maintaining our industry-leading financial bankability and production capacity.

These R&D investments have allowed us to consistently be among the solar cell efficiency innovators. LONGi broke the world record for cell conversion efficiency seven times across various cell types and architectures in 2021. We are one of the leaders in developing new high-efficiency cell technologies, including TOPCon and heterojunction (HJT) cells.

Again, why should installers care about all this cell efficiency innovation in the pipeline? Because in a few years, today’s 400-watt-plus modules will be a fond memory as the even more efficient 500- and 600-watt modules of the future get hoisted up to the rooftop for installation—saving time and money while harvesting and producing never-before seen amounts of energy per unit area.


By Hongbin Fang, LONGi Director of Product Marketing

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