Partial Shade Evaluation of Distributed Power Electronics for Photovoltaic Systems: Preprint

Research output: Contribution to conferencePaper


Site survey data for several residential installations are provided, showing the extent and frequency of shade throughout the year. This background information is used to design a representative shading test that is conducted on two side-by-side 8-kW photovoltaic (PV) installations. One system is equipped with a standard string inverter, while the other is equipped with microinverters on eachsolar panel. Partial shade is applied to both systems in a comprehensive range of shading conditions, simulating one of three shade extents. Under light shading conditions, the microinverter system produced the equivalent of 4% annual performance improvement, relative to the string inverter system. Under moderate shading conditions, the microinverter system outperformed the string invertersystem by 8%, and under heavy shading the microinverter increased relative performance by 12%. In all three cases, the percentage of performance loss that is recovered by the use of distributed power electronics is 40%-50%. Additionally, it was found that certain shading conditions can lead to additional losses in string inverters due to peak-power tracking errors and voltage limitations.
Original languageAmerican English
Number of pages8
StatePublished - 2012
Event2012 IEEE Photovoltaic Specialists Conference - Austin, Texas
Duration: 3 Jun 20128 Jun 2012


Conference2012 IEEE Photovoltaic Specialists Conference
CityAustin, Texas

NREL Publication Number

  • NREL/CP-5200-54039


  • DC-DC power converters
  • microinverters
  • mismatch
  • partial shading
  • photovoltaic systems


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