An Experimental Evaluation of the Performance of the Amorphous Silicon PV Array on the NCSU AFV Garage

Abstract

A comprehensive performance test has been conducted on the 3 kW amorphous silicon photovoltaic (PV) system on the roof of the Alternative Fuel Vehicle Garage of the North Carolina Solar Center. The purpose of this testing program was to measure the performance of the PV system, to determine if any deterioration has occurred over the past three years since installation, and to evaluate the performance of the individual circuits that makeup the PV system.

Test conducted on the individual circuits of the PV system showed significant differences. This is particularly true for the two different solar panel models, which were installed using different techniques. Numerous tests were conducted on these circuits to isolate the problem. The current-voltage curves of the factory-laminated panels were much worse than the self-laminated panels. No cause of the poor performance could be definitively established. Discussions with the PV panel manufacturer are continuing to identify the cause of the variation in PV circuit performance.

Comparisons made to performance data recorded in 2003-2004 show a similar kWh production over 3-month periods, this is encouraging. However, comparisons between global irradiance and AC power production show a 9% reduction in power production.

Continued research is recommended to further evaluate the circuit issues and to study how PV panel temperatures can be reduced so as to improve over PV system efficiencies.