Evolution of the United States' Solar Domestic Hot Water System Rating Program

The Solar Rating and Certification Corporation (SRCC) has recently implemented a novel simulation-based process for generating solar domentic hot water thermal performance ratings using TRNSYS 13.1. Experience has revealed several implementation issues that have lead to increased emphasis on system testing. First, many of the certified systems have incorporated components and processes that haveproven difficult to model, particularly with regard to heat exchangers, tanks, and natural convection loops. Consequently, the ability to rate all systems with literal modeling to a uniform uncertainty has been difficult to achieve. Second, the use of simulation models developed without rigid validation is not defensible, and can lead to decreased credibility. This paper summarizes these issues,and elaborates on the continuing research to produce validated models from either component based tests of whole system tests.