Dr. Yousef is interested in aspects of innovations in Solar photovoltaic (PV) systems. He has worked extensively in many solar PV areas including PV mathematical modeling, improving the efficiency and power extraction, partial shading impact, control of PV converters, PV faults and reliability improvement. One of his driving goals is to contribute toward expanding  utilization of solar PV systems through solving technical challenges impeding their growth.

One of his major contributions is the introduction of a new interdisciplinary field to solve existing problems in solar PV systems. The approach introduced optical cameras and computational vision, for the first time, to improve the power extraction of solar PV systems operating under partial shading conditions. The development of this technology became feasible after his earlier formulation of a fast estimator that made modeling partially shaded PV systems fast enough for the practical implementation of the innovative technology. 

The new interdisciplinary approach has been also utilized to improve the power extraction of differential power processing power converters eliminating the need of communication between the converters without sacrificing the accuracy. 

Some other featured contributions are summarized:

  • A reduction in the heavy computational time needed for simulating large, partially shaded PV systems has been provided by a proposed PV circuit model, which offers comparable accuracy but requires less computational time.
  • The estimation of power peaks for partially shaded PV systems is now possible in few seconds as opposed to the few hours previously required with existing methods. This was also utilized for the first-time development of a model-based MPPT for partially shaded PV systems which improves the dynamics of the tracking.
  • The use of MPPT methods that combine model-based and heuristic techniques, which feature reduced tracking power losses, has been facilitated by reducing their cost and complexity through the elimination of the previously required temperature measurements.
  • Misleading power losses have been eradicated for partially shaded PV systems through the development, for the first time, of a model-based MPPT method for use with partially shaded PV systems. The new method avoids the curve scanning required with existing MPPT methods.
  • Mismatch power losses in partially shaded PV systems have been minimized by the development of a new reconfiguration algorithm that reduces the time delay inherent in existing methods.

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