ISFH Researchers have evaluated five inverter based methods for fault diagnosis in photovoltaic systems, identifying practical approaches for detecting defects during normal daylight operation.
Defects in solar modules can reduce energy production and increase operating costs if they remain undetected. The study examined Daylight Photoluminescence, or DPL, as a method of identifying faults such as cell cracks and areas of increased series resistance before they result in significant performance losses.
DPL captures the weak infrared luminescence emitted by solar cells while they are generating electricity. Unlike conventional photoluminescence inspections, the technique can be used under sunlight without taking the photovoltaic system out of operation.
A key challenge is separating the weak luminescence signal from reflected sunlight. The researchers therefore investigated whether different inverter operating modes could be used to isolate the required signal without relying on expensive optical filters.
Five measurement approaches were assessed, including inverter IV sweep, inverter power control, inverter shutdown, dynamic shading of individual modules and Short Current Interruption.
The study also compared three image processing techniques: Dark Image Subtraction, Pearson Correlation Coefficient and Non Normalized Pearson Correlation Coefficient. The NNPCC method was developed specifically as part of the research.
The results showed that NNPCC provided substantially improved visualisation of defect structures compared with conventional PCC analysis.
Cell cracks and areas with increased series resistance were detected most reliably using IV sweep and inverter shutdown. These methods also showed the closest agreement with laboratory reference images.
Image quality was assessed using the Structural Similarity Index. The highest SSIM values, at approximately 0.65 to 0.66, were achieved when IV sweep and inverter shutdown were combined with either DIS or NNPCC.
Dynamic shading was also identified as a practical alternative for field inspections. The method briefly shades neighbouring modules while the inverter continues operating under Maximum Power Point Tracking.
This approach has the advantage of requiring no inverter reconfiguration, making it suitable for detailed inspection of individual modules under operating conditions.
The findings indicate that DPL could provide operators of large photovoltaic systems with a practical method for identifying defects and potential energy losses while reducing the need for system downtime.
The researchers suggest combining inverter shutdown for rapid system wide inspections with dynamic shading for more detailed assessment of individual modules. The combined approach could enable DPL based condition monitoring without rewiring or major changes to inverter configurations.
For photovoltaic operators, the technology could support earlier detection of faults, more efficient maintenance planning, reduced operating costs and improved system performance.
Author: Bryan Groenendaal
August 17, 2026
September 5, 2026
August 20, 2026
September 21, 2026
August 13, 2026
September 3, 2026
Disclaimer | Privacy Policy | Terms & Conditions | Returns Policy | Intellectual Property | Cookie Policy
© 2019 – 2026 GBA Digital Media Group. All Rights Reserved
Website Design | Website Maintenance
Copyright Green Building Africa 2026.
Subscribe to our weekly Top 5 Stories
"*" indicates required fields
You must be logged in to post a comment.