Correlation of Infrared Thermal Imaging Results with Visual Inspection and Current-Voltage Data of PV Modules Installed in Kumasi, a Hot, Humid Region of Sub-Saharan Africa

Gabriel Takyi

doi:10.3390/technologies5040067

Abstract

In this study, a photovoltaic (PV) modules site installed from 1997 to 2017 (20 years of outdoor exposure) in the hot, humid region of Kumasi, Ghana in Sub-Saharan Africa was selected in order to study the aging phenomenon and rate of degradation due to long-term exposure. The main purpose of this work was to correlate the performance of 14 PV modules using data from infra-red thermal imaging (hot spot tests), current-voltage (I-V) tests and visual inspection. The modules were first visually inspected followed by electrical performance tests using an I-V curve tracer. Hot spot testing of each module was performed to enable further characterization. The results of the visual inspection using the United States National Renewable Energy Laboratory (NREL) checklist did not show any major observable defects. The results also show that the higher the temperature difference in the hot spot tests, the higher the rate of power degradation. Eleven modules failed the hot spot tests according to the criteria indicated in the literature. The average power degradation rate was 1.36%/year, which is above the industry-accepted range of 0.7–1.0%/year. The results provide evidence of a positive correlation between temperature difference and performance parameters such as power degradation (Pdeg), power performance factor (PPF) and power drop (Pdrop). The power performance factor for all 14 modules fell below the average 80% standard set by most manufacturers for modules operating within the 25-year warranty.

Highlights

The global acceptance of solar photovoltaic (PV) has motivated several studies into the design and performance of PV systems
The results provide evidence of a positive correlation between temperature difference and performance parameters such as power degradation (Pdeg), power performance factor (PPF) and power drop (Pdrop)
The results of the visual inspection reported in our earlier paper (Quansah et al [19]) and reproduced here in Table 2 did not show any major visually observable defects

Summary

Introduction

The global acceptance of solar photovoltaic (PV) has motivated several studies into the design and performance of PV systems. Performance parameters are based on globally accepted standards designed by agencies such as the National Renewable Energy Laboratory (NREL), etc., as reported in the literature [1]. Factors that account for a drop in performance have been noted such as location of use, manufacturing companies (technologies involved), age and basic maintenance issues, as reported by Jordan et al [2] and NREL [3]. Warranties are becoming a competitive factor in the market. Several studies including Jordan et al [2] and Phono [4] have assessed different manufacturing companies and their improved methods of giving out warranties over the years. Tsanakas et al [5]

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Conclusion