Effect of Distributed Power Conversion on the Annual Performance of Building-Integrated PV Arrays With Complex Roof Geometries

Abstract

Building-integrated photovoltaic (BIPV) systems have gained greater popularity in recent years; however, their effectiveness is often limited by nonuniform operating conditions. To increase potential for energy capture in PV systems, particularly those with series string configurations, an improved module integrated dc-dc converter (MIC) with maximum power point tracking has been proposed. This paper investigates the potential power gain provided by these MICs in situations where the architecture or surroundings of a building necessitate that a PV array include panels with differing orientations, which can significantly reduce system efficiency. A flexible, comprehensive simulation model for BIPV systems is developed, which allows for variations in insolation and temperature at the PV cell level, while accurately modeling MICs and their effect on array performance. This model is used to simulate various directional array combinations in series string and parallel configurations for a representative set of climates around the US. Results of these simulations show power gains attributed to both the photovoltaic generator/converter portion of the system and to increased inverter efficiency arising from a constant, controlled string voltage. When differing panel orientations within an array are considered, there is potential for annual power output gains of over 10% for a system with MICs when compared to conventional approaches. Further opportunities for increased energy capture in a BIPV system with MICs are identified and discussed.

Performance and Economic Analysis of Distributed Power Electronics in Photovoltaic Systems

“…The above simulation results and additional results from literature are summarized in Table III below: Residential rooftop tree shadingmultiple strings 5-20% +20-30% of loss [5] Residential rooftop, pole shadingmultiple strings 4-8% +40-70% of loss [6] Commercial system with inter-row shading 1-5% +0% of loss ** [ Table II] Residential orientation mismatch within a string 1-20% ~100% of loss [11] Imp distribution mismatch 0.2 -1% ~100% of loss [ Fig. 4 …”