A program is described for the controlled degradation and evaluation of thin plastic film samples in a set of parallel (in time) exposures. The intent of the various exposures is to separate the effects of identifiable degradation mechanisms associated with each material’s use as a solar collector cover. The mechanisms considered were those due to: (i) environment less solar irradiation (chemical, abrasion, humidity, etc.); (ii) environment including solar irradiation; (iii) thermal effects and (iv) mechanical effects. The procedures described in the program are illustrated by presenting the details for the evaluation of two commonly used plastic films.