Performance Evaluation and Voltage-Domain Error Decomposition of the Single-Diode Photovoltaic Model Under Dynamic Operating Conditions

Egehan Akbaba and Ali Tunç
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Egehan Akbaba: Sanko Science and Technology High School, Gaziantep, Türkiye
Ali Tunç: Nuray - Tuncay Kara Science and Art Center, Gaziantep, Türkiye

European Journal of Multidisciplinary Studies, 2026, vol. 12, issue 1, 249-270

Abstract: Accurate modeling of photovoltaic array performance under dynamic field conditions is essential for power forecasting and electrical grid integration. Despite the widespread use of five-parameter single-diode models for annual yield estimation, their instantaneous predictive fidelity under operational extremes remains unconstrained. This study evaluates the dynamic accuracy of the standard single-diode framework using a 21-day telemetry dataset (2,909 active daylight observations, plane-of-array irradiance > 50 W/m²) from a 648-module SunPower SPR-327 photovoltaic array (System 1283, Golden, Colorado). All reported voltages and currents are array-level maximum-power-point quantities measured at the inverter DC input. Across all records, the model predicted DC power with a Mean Absolute Error (MAE) of 5.29 kW (5.57%), a Root Mean Square Error (RMSE) of 5.95 kW (6.26%), and a net bias of −3.98 kW (−4.19%). Under high-irradiance conditions (>800 W/m²), with module temperatures predominantly exceeding 55°C, systematic power under-prediction reached −6.29 kW. Error decomposition revealed that current predictions remained accurate to within 0.4% (bias of −1.91 A), while a 3.1% voltage deficit (−12.02 V) drove the power error. Conversely, low-irradiance (50–200 W/m²) discrepancies were highly sensitive to sensor selection, with voltage bias shifting from −0.84 V (reference cell) to +5.11 V (pyranometer). The deficit in high-irradiance voltage prediction points toward physical mechanisms in the voltage domain, such as the model's assumption of a temperature-independent series resistance or standard silicon thermal coefficient adjustments; however, these proposed mechanisms represent hypotheses generated by this analysis rather than confirmed causes. These results isolate the primary source of high-irradiance modeling error and establish target parameters for future calibration.

Keywords: photovoltaic modeling; single-diode model; voltage decomposition; series resistance; operational telemetry; field validation; module temperature (search for similar items in EconPapers)
Date: 2026
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Persistent link: https://EconPapers.repec.org/RePEc:eur:ejmsjr:634

DOI: 10.26417/5jwxm1re

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