Annual Degradation Rate and its Linearity Analysis using Metered kWh Data

The degradation rate analysis of 38 commercial crystalline-silicon (c-Si) photovoltaic (PV) power plants fielded for up to 16 years in a hot-dry climate of Arizona has been evaluated. Based on the metered kWh data and modeled weather data of these systems, the linearity and degradation rate analyses of PV modules are statistically determined using three different performance approaches: PR (Performance Ratio), PI (Performance Index), and Raw kWh. The evaluation approaches developed and used in this work are validated using the in-field current-voltage measurements previously performed in four commercial systems.