Comparison of PV module performance before and after 11 and 20 years of field exposure

In 1990 the Schatz Energy Research Center (SERC) installed a PV array comprised of 192 ARCO M-75 modules. Prior to installation, SERC measured the performance of each module. For the past 20 years the array has continued to operate in a cool, marine environment. The performance of each module was re-evaluated in 2001 and again last year in 2010. This paper describes the equipment and procedure used in retesting the modules, and reports module performance results. The average module maximum power production at one full sun and NOCT has progressively decreased from an initial 39.88W in 1990 to 38.13W in 2001 and to 33.43W in 2010. The average module maximum power production fell by an average of 0.4%/yr from 1990 to 2001 and by an average of 1.4%/yr from 2001 to 2010.