Earlier this month, SolarCity made the claim that solar panels coming off of its 100-megawatt Silevo pilot production line were setting world records for solar module efficiency as "the world’s most efficient rooftop solar panel, with a module efficiency exceeding 22 percent." A week later, Panasonic claimed the crown at 22.5 percent module efficiency.
A chart might help clear things up.
SolarCity’s panel was measured with 22.04 percent module-level efficiency by the Renewable Energy Test Center. The silicon-based bifacial PV cell combines n-type substrates, copper electrodes, thin-film passivation layers, and a tunneling oxide layer that yields high conversion efficiencies.
SolarCity claims that its module will be "the highest-volume solar panel manufactured in the Western Hemisphere." Production will begin this month at the firm's 100-megawatt pilot facility, but most of the new solar panels will be produced at SolarCity’s 1-gigawatt factory in upstate New York. Full production will be between 9,000 and 10,000 solar panels per day when the Buffalo facility hits full capacity.
SolarCity CTO Peter Rive noted that the record panel was manufactured on the company's 100-megawatt pilot production line -- the Buffalo factory won't be at full production until 2017. Rive acknowledged that the 22 percent panel is "on the high end," but also noted that a majority of panels are hitting 21.8 percent.
SunPower claims its X-Series panels are the "most efficient panel on the market today" with an efficiency of 21.5 percent. The company also says demand for its X-Series product is "extremely high," with "manufacturing volume [set] to increase more than 300 percent year-over-year." Average cell efficiency across all SunPower lines was close to 23 percent during the quarter, according to the company. A reliable source at SunPower told GTM that 22 percent efficiency panels were already coming off of its line.
A SunPower spokesperson added, "As a company that is leading in providing customers around the globe with the world’s most efficient solar panels, SunPower always welcomes others to the efficiency race. It’s great that we all agree -- efficiency matters. We’re proud that we’ve been shipping the industry’s highest-efficiency solar panels for years, and some of our customers are receiving panels with greater than 22 percent efficiency."
A source suggests that there are enough SunPower panels at the factory with greater than 22 percent efficiency to build a 10-kilowatt system, starting with panel serial number J19M20279602.
Source: Wiley Online
Panasonic: As covered in PV Magazine, the Panasonic panel’s 22.5 percent conversion efficiency was verified by Japan’s National Institute of Advanced Industrial Science and Technology "and builds upon the 25.6% efficiency record the company set in 2014 at cell level."
World-record claims of this nature, absent actual distribution, yield and volume data, are mostly bluster and stunt specmanship.
An anonymous source suggested, "In solar, cost is king. Energy is a commodity, after all. With [balance-of-systems] costs declining, efficiency has less leverage on total system cost."
In any case, SolarCity's pilot production line holds the title for now.