ISO 9459-4:2013规定了一种评估太阳能热水器年度能量性能的方法，该方法使用组件性能测试结果和数学模型的组合来确定特定天气和负载条件下的年度负载循环任务性能。该程序适用于太阳能热水器，该热水器具有集成备用或预热到传统储水式或瞬时式热水器中，以及集成收集器储水式热水器。 ISO 9459中规定的系统操作要求- 4: 2013年旨在确定家用热水器的年度性能评级。ISO 9459-4:2013中没有产品设计或操作要求。

ISO 9459-4:2013 specifies a method of evaluating the annual energy performance of solar water heaters using a combination of test results for component performance and a mathematical model to determine an annual load cycle task performance under specified weather and load conditions. The procedure is applicable to solar water heaters with integral backup or preheating into a conventional storage or instantaneous water heater and to integral collector storage water heaters. System operating requirements specified in ISO 9459-4:2013 are for the purpose of determining an annual performance rating for domestic water heaters. There are no product design or operation requirements in ISO 9459-4:2013.