By MA Yueran
Solar panel maker Longi has shaken up a sleepy industry by announcing it will go against the trend and bet on back-contact batteries. All of the company’s investment will now be in back-contact.
Solar panel makers are graduating from the old, cheap P-Type to a more efficient and longer-lasting alternative called N-Type. Within this new category, there are three kinds of cells – TOPCon (Tunnel Oxide Passivated Contact), Heterojunction (HJT), and back-contact.
Numerous tradeoffs
Back-contact cells were invented by the Silicon Valley company SunPower. They have both contacts at the back, which allows the entire front of the panel to be exposed to sunlight and thus makes the battery more efficient. But SunPower’s manufacturing method is expensive, which deterred other solar cell makers until recently.
TOPCon and HJT are considered more viable options. TOPCon is the less costly of the two and has attracted a lot more investment. The technology, arguably, is approaching a ceiling in terms of efficiency and capacity. HJT batteries are thinner and more powerful but raw materials are expensive.
Chinese solar cell makers have made meaningful progress in back-contact technology. Longi launched its first HPBC products last year (short for Hybrid Passivated Back-contact Cell), upgraded P-type cells with some back-contact technology. The company has been making P-type cells for a long time and the existing capacity was remodeled for the new products.
A 30 GW HPBC factory will go into operation by the end of the year. Longi produced only 1.5 GW of HPBC batteries in the first half of the year.
Quest for power
Longi is the world’s biggest maker of silicon wafers (the small components that form solar panels) but behind its peers in N-Type. The company has lost 40 percent of its market cap this year, but part of it is due to the general woes of the solar industry.
TCL, another big solar cell maker, has been collaborating with Maxeon, a Sunpower spinoff and a leader in back-contact technology, since 2012. TCL’s most recent factory makes TOPCon batteries.
Shanghai Aiko Solar, on the other hand, already has at least two back-contact products. A 6.5 GW factory in Zhuhai recently went into production. People familiar with the industry say its technology is different from Longi’s. Aiko is more powerful, but Longi may cost less.
A handful of solar companies have back-content patents but are still far from mass production.
