Prof. Franz Baumgartner: Performance comparison: solar module-level power electronics vs. conventional string inverters

Stefan Leitner (Organiser)

Activity: Participation in or organisation ofPublic lecture or debate (Participation in/Organisation of)


Commercially available PV module-level based power electronics currently exhibits an increasing market share with
global revenues of over 2 B$. Companies are promising performance advantages of up to 20 % due to partial
shading of individual modules and optimal control of the DC/DC converters per solar module, compared to a single
operating point of a conventional string inverter. Measurements of such commercial PV module-level based power
optimizers (each one fed by a different power supply from an individual DC source which is emulating an individually
shaded solar module) performed at ZHAW laboratories, revealed a significant deviation between the predicted performance
improvement and observed values. The measurement data and analyses obtained at ZHAW, together
with a comparison of several publications on this topic, provide a helpful overview for practical applications. Finally,
PROS and CONS of both PV system setups (module-based vs string inverter based) are summarized. This also
includes parameters such lifetime of the system components, service cost and popular web-based illustrations of
the aforementioned performance values of such systems.
Period1 Dec 2020
Event typeOther
Degree of RecognitionInternational

Fields of Expertise

  • Sustainable Systems
  • Mobility & Production