To study the long-term performance reliability of a solar powered carbon/methanol ice maker, an investigation of thermal decomposition of methanol on the alloy＇s surface under solid adsorption refrigeration conditions has been carried out at Monash University. The indoor simulation showed that the thermal decomposition of methanol did occur in the normal solar powered adsorption refrigeration system. Dimethyl-ether and methoxymethyl methyl ether etc, were found in the decomposition products. The rate of the decomposition depends on the presence of various alloys. These decomposition products (unwanted gases) may be one of the main reasons for the diminishing performance of the solar ice maker. The impact of the unwanted gases on the ideal solar powered solid adsorption refrigeration cycle is also discussed in this paper.