Distributed power-management architecture for a low-profile concentrating-PV system

This paper presents a low-cost dc-dc distributed power-management architecture for a low-profile concentrating-photovoltaic (CPV) system. The proposed scheme uses inverting buck-boost converters connected across neighboring series-connected CPV cells to achieve a virtual-parallel connection and thus improve the tolerance of the overall system to parameter variations. Since the converters process the difference between corresponding cell currents and the string current, they have reduced power-handling and efficiency requirements. Current cascading is identified as the main challenge with this architecture. Statistical simulations are used to investigate the current distributions in the converters, and power benefits are analyzed using measured data from a six-cell CPV system. Experimental results from four- and three-cell systems using digitally controlled converters demonstrate clear power benefits in the presence of tracker misalignment and short-circuit current mismatches.

I. Introduction

Worldwide interest in harvesting solar energy using photovoltaic (PV) panels has grown dramatically in recent years. While conventional mono-crystalline silicon and thin-film technologies dominate the market today, new concentrating-PV (CPV) systems are emerging as a promising alternative in certain markets [1], [2]. CPV technology uses 500–1000× less semiconductor material than conventional PV modules, and replaces it with low-cost recyclable materials, enabling rapid scale-up with low capital costs [3].