In-depth investigation of effects of partial shading on PV array characteristics

The output characteristics of photovoltaic (PV) generation system depend on environmental factors such as solar insolation and cell temperature. PV systems sometimes subject to partial shading, the probability for large scale PV system is very large. Under partially shaded conditions, I-U characteristic of PV array exhibits multiple stairs, and P-U characteristic of PV array shows multiple peaks. Traditional maximum power point tracing (MPPT) algorithm only converges to local peak, not the global peak. This paper investigates in-depth the effects of partial shading on PV array characteristics, and several important observations or conclusions are summarized, which helps to provide experiences or references for developing an effective global MPPT scheme under partially shaded conditions.