Encapsulant browning is one of the most common degradation modes found in crystalline silicon field-aged photovoltaic modules. Browning, usually undetected unless severe, reduces the short-circuit current ( I sc) produced by a module. Therefore, field-aged browned modules have been subjected to accelerated UV testing to obtain true end-of-life activation energy for the encapsulant browning mechanism. A novel time- and resource-saving accelerated UV exposure testing method simultaneously allowing multiple module temperatures to be maintained in a single chamber run is presented. Six field-aged crystalline silicon modules of glass/backsheet construction (three each from BP Solar/Solarex MSX 60 and Siemens M55) with similar glass and encapsulant formulation were exposed to a UV dosage of 450 kWh/m2. Through passive heating, the average module temperatures for the BP Solar/Solarex modules were 60 °C, 77 °C, and 85 °C and those of Siemens M55 were 75 °C, 80 °C, and 837 °C. To study UV browning, the modules were intermittently characterized through visual imaging, UV fluorescence imaging, electroluminescence imaging, quantum efficiency measurements, module, and cell-level light I – V measurements. An I sc decrease corroborated the increased extent of browning with increased module temperature. For the BP Solar/Solarex modules, the Low T, Mid T, and the High T modules showed a 1.37%, 2.48%, and 3.26% I sc drop, respectively. The Siemens modules showed a 4.11%, 5.65%, and 6.95% I sc drop. The multiple cell-level I sc data points obtained for each module temperature increased provided statistical significance. Activation energy for encapsulant browning was calculated as 0.44 and 0.72 eV for MSX 60 and M55 modules, respectively.