Spacecraft powered by solar arrays are at risk of significant degradation when operating in high-irradiance, high-temperature environments on extended missions. Testing of common solar array adhesives in the John Hopkins University/Applied Physics Laboratory Combined Environment Test Chamber has identified a potential degradation mechanism. In addition, the APL testing separates the effects of thermal, UV, and charged particle fluence. Experimental design and experimental results are discussed in detail with funding support from the NASA Solar Probe Plus project.