The efficiency of solar panels is an important metric to both solar companies and to its customers. When panels are more efficient it mean that rooftops can be covered in fewer efficient panels, which use less materials, but that can generate the same amount of energy as more less-efficient panels.

SunPower says its highly efficient panels can generate 70% more energy in the same space over the first 25 years, compared to less efficient panels. Many solar panels are somewhere between 15% and 18% efficient. SunPower and others have been working to boost the efficiency of panels using material science and optics tech innovations.

These are the economics behind clean energy:

Solar companies are in a battle to boost the efficiency of their panels and tout new records. SunPower (SPWR) says its 22.8% solar panel was verified by the federal National Renewable Energy Laboratory.

Last year, SolarCity claimed that it had started making its own highly efficient panels, with an efficiency that “exceeded 22%,” verified by the Renewable Energy Test Center (which isn’t one of the more commonly used verification labs). But SolarCity’s (SCTY) solar panels were also planned to be made in small volumes on a pilot solar panel manufacturing line in Fremont, Calif.

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Creating solar panel efficiency breakthroughs in the lab or on a small scale, is far easier than making those efficient panels in very large volumes. But SunPower says the average efficiency of its solar cells (which make up panels) at the end of last year was close to 23%.

SunPower’s stock was up over 3% in morning trading to $21.84. Oil giant Total owns 66% of the Richmond, Calif.-based SunPower.

Check out Fortune’s recent interview with SunPower CEO Tom Werner.

Last week SunPower announced fourth quarter and year 2015 earnings. SunPower says it generated $1.58 billion in revenue in 2015, with an annual loss of $299.44 million. The company was profitable on an annual basis in 2014 and 2013.