The Effect of Measurement Uncertainty and Environment on Domestic Solar Water Heating Systems’ Energy Efficiency Grades

In China, two important national standards were implemented on Aug 1st, 2012, one is ‘Specification of domestic solar water heating systems’ (GB/T 19141-2011), the other is ‘Minimum allowable values of energy efficiency and energy efficiency grades for domestic solar water heating systems’ (GB 26969-2011). According to these two standards, the energy efficiency grades indicator CTP (coefficient of thermal performance) should be tested and calculated by daily useful energy and average heat loss factor of domestic solar heating system. Through experiment and calculation, the effect of measurement uncertainty and daily average ambient temperature on the migration of domestic solar water heating systems’ (DSWHS) energy efficiency grades was discussed. The calculation and analysis methods may be helpful for data consistency co-verfication between different inspection organizations.