Technical evaluation of a dual-junction same-band-gap amorphous silicon photovoltaic system at NREL

On December 7, 1992, a 1.8-kW/sub AC/ utility-interconnect photovoltaic (PV) system using amorphous silicon modules was brought on-line at the National Renewable Energy Laboratory's photovoltaic test site. This system was deployed to conduct an in-situ technical evaluation of the PV array (in a high voltage configuration) and system performance and reliability in a utility-interconnect application. The system is unique due to the installation of construction-grade insulation on the back of each PV module. This use of insulation is an attempt to levelize the annual array power output by elevating the operating temperature of the modules. This paper presents array and system performance data. Emphasis is placed on quantifying the effects of individual losses as well as seasonal changes on PV array and system performance.