In 1990 the Schatz Energy Research Center (SERC) installed a PV array comprised of 192 ARCO M-75 modules. Prior to installation, Zoellick [1] carefully measured module performance and reported average peak power at normal operating cell temperature (NOCT) to be 39.88 W, which was 14.1% lower than the 46.4 W nameplate rating. For the past 11 years the array has been exposed to and employed in a cool, marine environment. Of the original 192 modules, 191 were recently tested in order to re-evaluate their performance.This paper describes the equipment, conditions, and procedure used in retesting the modules, and reports module performance results. Notable results are that average module short circuit current and maximum power production at NOCT have decreased by 6.38% and 4.39%, respectively.

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alkyl and alkyl-oxygen nonbonding interactions that are greater in the hydroxylamines and oximes than in the corresponding radicals, since the latter have a more open geometry. In addition, nonbonding interactions involving the hydrogen that is removed are eliminated.These steric effects on the O-H bond strength should be at a maximum with di-/er?-butyl nitroxide23 in which the relevant CNC angle is 136°and the CNO angle is 112°. In the hydroxylamine, if the nitrogen is tetrahedral, the angles will be 108°. Unfortunately ditert-butyl nitroxide reacted so slowly with hydrazobenzene in CC14 and in benzene that the heat of the reaction could not be determined. The slowness of reaction suggests that the O-H bond strength in this compound is several kcal/mole less than in 1, since the sterically more hindered but thermoneutral hydrogen transfer from di-?er/-butylhydroxylamine has a rate constant of over 102 M~l sec-1 in CC14 at room temperature.31The importance of steric factors in determining the O-H bond strength in 1 is difficult to estimate. However, the six-membered ring should inhibit any large changes in the CNC angle on going from the hydroxylamine to the radical, so steric effects are probably small. It is interesting to note that the nitrogen hyperfine splitting for 1 in most solvents is similar to the values found for many less substituted and unstable, dialkyl nitroxides. In these radicals the alkyl groups are free to adopt a conformation minimizing steric interactions. We would accordingly predict that the O-H bond strengths in unhindered dialkylhydroxylamines are in the range 72-74 kcal/mol.Steric effects should be absent in the bicyclic nitroxides 3 and 4.

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