High-gain DC-DC conversion for parallel photovoltaic arrays

A new approach to photovoltaic (PV) arrays is proposed based on a parallel connection scheme. In a series-connected array, differing insolation due to shading or obstructions causes disproportionate reduction in power output. Because operating voltage is governed more by temperature than by insolation, a parallel-connected array is much more robust to the shading effect. Direct paralleling is inappropriate due to the low voltage of a conventional PV module. Therefore, high-gain dc-dc converters are introduced in the proposed system. Three converter types are discussed. Two use transformers to increase gain and one uses a tapped inductor. Experimental results validate the concept and demonstrate tracking accuracy up to 99.87% despite a 39% difference in insolation, and weighted efficiency of up to 92.9%.