A DC voltage estimation at the maximum power point of a series parallel connection PV system with partial shade

Abstract

This paper describes a DC voltage estimation at the maximum power point of a series parallel connection photovoltaic (PV) system with partial shade. The PV system converts sunlight into electric power. The IV (current-voltage) curve of the solar cell describes its energy conversion capability at the existing conditions of light level. The PV (power-voltage) curve which determines the maximum output power is computed from the IV curve. It is necessary to operate the solar cell at the voltage which provides the maximum power. The maximum power point tracking (MPPT) control using hill-climbing method is widely used. However, the output power from the PV system is reduced if weather condition changes and the area of the receiving portion of the PV panel decreases. In these cases, IV characteristics of the PV panel also changes. There is a possibility that the maximum power point cannot be captured by the conventional MPPT control in case that the maximum power would be two or more. We propose a method for the estimation of the DC voltage at the maximum power point by using the equivalent circuit of the solar cell.