Comparative Performance and Model Agreement of Three Common Photovoltaic Array Configurations.

Area of Science:

• Solar Energy
• Photovoltaics
• Renewable Energy Systems

Background:

• Monocrystalline silicon photovoltaic (PV) arrays are widely used for grid-connected power generation.
• Understanding the performance variations of PV arrays under different installation conditions is crucial for optimizing energy yield.

Purpose of the Study:

• To compare the performance of three grid-connected monocrystalline silicon PV arrays with varying configurations.
• To validate performance models using on-site weather data and measured array outputs.

Main Methods:

• Instrumentation and 1-year monitoring of three PV arrays (73 kW to 271 kW) with different tilts, orientations, and locations (parking lot, open field, flat roof).
• Analysis of measured relationships and standard metrics to evaluate relative array performance.
• Development and validation of comprehensive performance models using pvsyst software.

Main Results:

• All three arrays consistently achieved monthly performance ratios (PRs) above 0.75.
• Significant differences in relative output were observed, strongly correlating with operating temperature and, to a lesser extent, orientation.
• pvsyst model predictions were within 5% of monthly delivered energy, except during winter snow events and maintenance outages.

Conclusions:

• PV array performance is significantly influenced by operating temperature and orientation.
• Performance models provide reliable energy output predictions when validated with site-specific weather data.
• Environmental factors like snow cover and system downtime can impact PV energy yield.