Mismatch Power Losses Minimization in Photovoltaic Array

Abstract

The mismatch in current-voltage (I-V) characteristics of Photovoltaic (PV) modules causes significant power loss in a large PV array, which is known as mismatch power loss (MML). In a PV array MML depends on several factors, such as partial shading, manufacturing tolerance and non-uniform aging. Recent investigations have reported that in PV array MML varies from 1% to 10% due to manufacturing tolerance (±3% to ±5%) and power degradation is typically 0.8% per year due to aging of PV modules and the economic loss is very significant. In this work, different conventional MML reduction techniques are investigated and an adaptive genetic algorithm (GA) based module rearrangement technique has been proposed for MML reduction both in new and aged PV arrays. For new PV arrays, MML due to manufacturing tolerances is investigated using 400 W, 3400 W, and 9880 W PV arrays with different (1×40, 2×20, 4×10, 5×8 40×1, 20×2, 10×4, and 8×5) series-parallel (SP) configurations. MML due to non-uniform aging is investigated using 400 W, 1.6 kW, 3.2 kW, and 10 kW aged PV arrays with the same SP configurations. Simulation and experimental results show that GA based module rearrangement technique performed better than conventional techniques both for new and aged PV arrays. For new PV array a maximum percentage of recoverable energy %RE of 4.15 % is recorded for 5×8 SP array by applying GA based MML reduction method. The GA based technique yields a maximum %RE of 4.67% for two years aged 8×5 SP array configuration. In addition, the performance of conventional array configurations (SP, TCT, BL, HC, and LD) and hybrid array configurations (HC-TCT, LD-TCT, TCT-S, S-TCT, SP-LD, LD-SP, and SP-TCT) are also investigated for MML reduction using non-uniformly aged PV array with different dimensions. Experimental results show that most of the hybrid array configurations are performed better than conventional interconnection topologies with respect to MML% mitigation for non-uniformly aged PV array. A maximum %RE of 15.94% is recorded for LD-SP configuration compared with most conventional SP configuration for a 400 W PV array. Moreover, a case study is performed to investigate the daily, monthly and yearly economic benefit of GA based MML reduction of a 28 MW PV plant both at new and aged conditions. The results show that %RE is 1.2% at the time of installation and 1.5% after three years and accordingly the annual extra revenue will be BDT 6585463.64 and 7935299.22 respectively for the 28 MW plant.