A performance evaluation of crystalline and amorphous silicon photovoltaic(PV) modules is presented in the light of their ability to perform as a demand side management (DSM) tool. Roof mounted, fixed-axis PV modules provide a very close match between their outputs and building peak load. The data presented is from the Virginia Tech Solar Test Facility (VTSTF) over the two year period from June 1989 to May 1991. The VTSTF is comprised three types of modules; Solarex SA20 (616 watts), ARCO Solar M55 (954 watts), and ARCO Solar G4000 (680 watts). Also the load of a six story academic building, on which the arrays are mounted, is monitored. The meteorological station collects weather information from the top of the building every 10 minutes. During the two years, the station has produced over 3.7 megawatt-hr of DC energy. During the first year of operation the SA20, M55, and the G4000 arrays produced 21%, 30%, and 30% of their rated DC energy. In the second year the corresponding numbers were 20%, 30%, and 25%. These values are normalized with the number of days of operation. A comparative analysis shows that for DSM applications, 2-axis tracking provides only marginal benefits, and may not be cost effective.
