Which Solar Panels Are The Most Efficient?: 21.5% SunPower solar modules�hold the�commercial solar module efficiency record.�SunPower’s SPR-327NE-WHT-D�modules�are also the leading solar modules in solar module yield field tests, and other SunPower solar modules come in #2 and #3 in those tests. (For those of you to who this matters or is interesting, SunPower is a US-based solar panel company.)