Eight single-family-sized solar domestic water heaters and a conventional electric water heater have been installed in the Alabama Solar Energy Center's Solar Test Facility for the purpose of acquiring comparative performance and operational data under identical operational and climatic conditions. The systems employ three examples of freeze protection typically encountered in the Tennessee Valley, (e.g., oil, antifreeze, and drainback).

Six of the systems are commercially available and are typical of those widely merchandized within the colder climates of the U,S. The other two systems were developed by TVA for the "Memphis 1000" demonstration program. The six commercial systems have been under test and evaluation for approximately 1 1/2 yrs. Testing results of these systems have been recently published. The two "Memphis 1000" systems are being tested under contract to TVA and this paper is the first public disclosure of the limited amount of data collected on these systems thus far.

The systems are installed side-by-side on a typical residential-type roof structure and are instrumented with totalizing Btu and Kilowatt hour meters to provide totalized values of energy flows. Total radiation in the horizontal and- tilted planes are measured to allow computation of system efficiencies.

In this paper, the details of the facility, systems and instrumentation will be described. Operational experiences with the systems will be reviewed and perforamance data will be presented.