Accession Number : ADA306567

Title :   Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska.

Descriptive Note : Final rept.,

Corporate Author : JET PROPULSION LAB PASADENA CA

Personal Author(s) : Gaines, G. B. ; Thomas, R. E. ; Noel, G. T. ; Shilliday, T. S. ; Wood, V. E.

PDF Url : ADA306567

Report Date : 07 JUN 1979

Pagination or Media Count : 63

Abstract : This report describes an accelerated test which is designed to predict the life of the 25-kW photovoltaic array installed near Mead, Nebraska. Emphasis is placed on the power-output degradation at the module level and on long-term degradation modes, as appropriate for life prediction of mature devices for which infant failures are few. A quantitative model for accelerating testing using multiple environmental stresses is used to develop the test design. The model accounts for the effects of thermal stress by a relation of the Arrhenius form. This relation is then corrected for the effects of nonthermal environmental stresses, such as relative humidity, atmospheric pollutants, and ultraviolet radiation. The correction factors for the nonthermal stresses include temperature-dependent exponents to account for the effects of interactions between thermal and nonthermal stresses on the rate of degradation of power output. A priori quantitative estimates of the model parameters are then used to compute expected degradation rates under various test conditions associated with a complete factorial experimental design. The conditions at the center point of the accelerated test design are selected to cause a loss of 50 percent of the initial power output for the modules over a period of approximately 8 months. The times to failure for other test conditions are then computed and the conditions are adjusted to yield expected failure times between approximately 1 month and 2 years. The resulting model is then used to obtain extrapolated estimates of the expected life of the modules currently operating at Mead, Nebraska. The test conditions, measurements, and data analyses for the accelerated tests are presented for determining the predicted life of the modules in service at Mead. Constant-temperature, cyclic-temperature, and UV types of tests are specified.

Descriptors :   *SOLAR CELLS, *PHOTOVOLTAIC EFFECT, *SOLAR PANELS, ULTRAVIOLET RADIATION, CORROSION, LIFE EXPECTANCY(SERVICE LIFE), AIR POLLUTION, ARRAYS, SUBSTRATES, TRANSITION TEMPERATURE, THERMAL CONDUCTIVITY, CIRCUIT INTERCONNECTIONS, MODULES(ELECTRONICS), ELECTRIC POWER, ELECTRICAL RESISTANCE, REFLECTANCE, ANTIREFLECTION COATINGS, ACCELERATED TESTING, THERMAL DEGRADATION, THERMAL STRESSES, HUMIDITY, CYCLIC LOADS, ELECTRIC SHUNTS.

Subject Categories : Electric Power Production and Distribution
      Electrooptical and Optoelectronic Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE