SunPower®

SunPower is a name that carries weight in the solar industry unlike almost any other. Founded in 1985 by Stanford electrical engineering professor Richard Swanson, the company grew from a two-thousand-dollar investment and a lab efficiency record into one of the most recognized solar brands in the world. Now operating from its national footprint with a presence in Vernon Hills, Illinois, SunPower brings 41 years of solar-specific experience to the Illinois market, a tenure that dwarfs the vast majority of installers on any state ranking.

The company's technical pedigree is difficult to overstate. SunPower's Maxeon cell technology, now manufactured through the spun-off Maxeon Solar Technologies division, has repeatedly set world records for solar panel efficiency, most recently achieving 24.7 percent apertured efficiency for a full-size module. For Illinois homeowners, where roof space can be limited and winter production matters, higher-efficiency panels translate directly into more kilowatt-hours per square foot of array. SunPower's NABCEP-certified installation teams in the Illinois market operate under a standardized quality framework that reflects the company's decades of process refinement.

Where SunPower loses ground in our evaluation is customer satisfaction. A 4.1-star Google rating across 452 reviews is solid by general business standards but falls below the 4.5-plus range that characterizes most top-ranked local installers. This is a pattern common to large national solar companies: the operational complexity of managing installations across dozens of states inevitably creates friction points that smaller, owner-operated firms avoid. Some Illinois customers have reported longer-than-expected timelines and difficulty reaching support staff, issues that are not uncommon when local installation crews are managed through a national corporate structure.

Despite those customer experience gaps, SunPower's score in our methodology benefits significantly from their equipment quality, brand longevity, financial stability, and NABCEP credentials. They offer cash and loan financing and handle projects across the greater Chicago metro and northern Illinois corridor.

With a composite score of 80.2 out of 100, SunPower holds the second-ranked position among solar installers in Illinois for 2026.