Background
An energy company operating a 189 MWdc utility-scale solar photovoltaic (PV) plant the largest in sub-Saharan Africa experienced a catastrophic inverter failure that raised immediate concerns around equipment reliability, operational safety, and potential recurrence.
Given the scale of the asset and its role in power generation, the client required an independent technical assessment to determine the failure mechanism and define a clear path to restoring stable and reliable operation.
Challenge
The inverter failure resulted in operational downtime and introduced significant uncertainty around the integrity of critical power electronics components.
At the time of the incident, it was unclear whether the failure was driven by:
- Equipment design limitations
- Protection settings
- Installation practices
- Site-specific operating conditions
Without a structured forensic investigation and root cause assessment, the plant faced:
- Risk of repeat failures
- Ongoing exposure to safety and warranty issues
- Financial and operational uncertainty across a flagship solar asset
The immediate challenge was to isolate the failure drivers and determine whether the issue was systemic or isolated, in order to guide corrective action with confidence.
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Solution
EPE conducted a detailed forensic investigation, analysing incident data, operating records, equipment specifications, and historical performance benchmarks to reconstruct the failure scenario.
The investigation extended beyond site-level analysis to include:
- Device-level evaluation of inverter components (including IGBT behaviour)
- Benchmarking against comparable sites and operating conditions
- Cross-validation of assumptions with client subject matter experts
This structured approach enabled the identification of probable failure mechanisms and clarified the contributing factors behind the event.
EPE delivered a comprehensive incident review and technical report, supported by:
- Root cause identification
- Prioritised corrective actions
- Recommendations for further modelling, testing, and validation
Key Insight
The failure was not attributable to a single factor in isolation but required multi-level analysis across equipment behaviour, system conditions, and operational context.
Understanding the interaction between device-level performance and system-level conditions proved critical to isolating the likely failure drivers.
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Result
The client obtained a clear technical understanding of the likely causes of the inverter failure and a structured path forward for mitigation.
This enabled:
- Prioritisation of corrective actions
- Reduction of recurrence risk
- Improved confidence in operational safety and equipment performance
- Faster, more informed decision-making following the incident
The investigation provided a foundation for restoring stable plant operation while protecting long-term asset reliability.
Why It Mattered
In utility-scale PV plants, inverter performance is central to both energy production and overall system stability.
This engagement ensured that a critical failure was not only understood, but translated into actionable steps to prevent recurrence enabling the client to restore operational confidence and maintain reliability across a key generation asset.
In an environment where power infrastructure is expected to operate under increasing stress and uncertainty, the ability to rapidly diagnose, resolve, and prevent failure becomes critical to maintaining continuity and long-term system resilience.