Effects of Reactive Power on Photovoltaic Inverter Reliability and Lifetime

Research output: Contribution to conferencePaperpeer-review

3 Scopus Citations


This paper performs research on predicting Photovoltaic (PV) inverters reliability and lifetime based on thermal cycling. Thermal cycling is considered the most important stressors in an inverter system. In order to achieve this, a detailed electro-thermal model of the PV inverter will be developed along with their controllers capable of providing voltage support through reactive power. An in-house inverter was built, and a PV inverter model was developed to match the physical inverter. The PV inverter electrothermal model was validated for different ambient temperatures to match the in-house inverter hardware. The in-house inverter was placed inside a thermal chamber to emulate different ambient temperatures and their losses and temperature rises within the system were measured. After the validation of the model, a reduced order model of the inverter will be implemented to translate the mission profile of ambient temperature and solar irradiance into load profile of junction temperatures of the switches. The junction temperature data will be used to identify the reliability indices and hence predict the useful lifetime of the inverter system. Along with the model to predict useful lifetime of the system, the impact of reactive power on the overall reliability of the system will be studied. The key observation in this paper shows that lifetime of the inverter decreases as the operating power factor moves away from unity.

Original languageAmerican English
Number of pages7
StatePublished - Jun 2019
Event46th IEEE Photovoltaic Specialists Conference, PVSC 2019 - Chicago, United States
Duration: 16 Jun 201921 Jun 2019


Conference46th IEEE Photovoltaic Specialists Conference, PVSC 2019
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5D00-73648 for preprint

NREL Publication Number

  • NREL/CP-5D00-76348


  • Inverter reliability
  • lifetime estimation
  • loss model
  • rain flow counting
  • thermal model


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