Report Number




Solar Thermal; Solar Energy


Thermal performance ratings, derived from the FSEC testing and certification program, are a useful tool in comparing the efficiency and economics of various flat-plate solar collectors. Since collectors used in domestic hot water (DHW) systems typically operate in the intermediate temperature range (1200F-1600F), this is the rating provided for comparisons. It must be stressed that these comparisons are only a guide and should not be considered as a rank ordering of collectors. Such considerations as component sizing and proper installation procedures are equally important in determining a system's overall efficiency. In addition, because of the variability of weather conditions, instrumentation accuracies, and other test condition constraints, the thermal performance of any two collectors should be considered approximately the same if their ratings are within 25 Btu/(ft2day) of each other. Bear in mind that comparisons based on these ratings address thermal efficiency and energy output per investment dollar only; they do not imply equivalent reliability or durability among collectors.

Date Published


Local Subjects

Solar Energy; Solar Thermal


FSEC Energy Research Center® Collection



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