Minimizing the effects of shadowing in a PV module by means of active voltage sharing

Negative effects in a two-section-module PV system due to shadowing are minimized by using active voltage sharing of section voltages. Instead of conventional bypass diodes, a bidirectional buck-boost-type circuit with current control guarantees equal section voltages yielding a unique maximum power point for the global system. Connecting an external maximum point power tracking (MPPT) converter results in bigger power extraction than the one obtained with the bypass diodes case, the improvement being in some cases up to 40%. Also, voltage values corresponding to the maximum power point (MPP) are less scattered than in the bypass diode solution, this facilitating the MPPT converter operation. To improve the efficiency, the current control strategy permits to identify the conditions to disconnect the bypass. PSIM simulations verify the theoretical predictions of the proposed technique.