SAN JOSE, Calif., June 27, 2016 /PRNewswire/ -- SunPower has again set a new solar power panel efficiency record, as validated by the U.S. Department of Energy's National Renewable Energy Laboratory ( NREL ). After achieving 22.8 percent efficiency for its X-Series solar panel earlier this year, SunPower has reached 24.1 percent efficiency – surpassing the previous world record for the highest efficiency of a solar panel using silicon cells.