2. P&O combined with PSO

Another hybrid MPPT technique for partial shading mitigation based on the combination of P&O and PSO is proposed in [154,155]. PSO is used in the initial phase to track the global peak, and then P&O is executed in the final phase. Compared to the conventional PSO, the advantage of this method is that it can track the global peak in a shorter time and has a faster convergence time with better dynamic performance. The hybrid approach has been tested in [154] with different shading scenarios, and to reduce the ripple current, the boost converter is modified to have an interleaved topology.

### 3. Differential Evolution and PSO (DEPSO)

 

The PSO, combined with differential evolution (DE), creates an algorithm efficient in tracking the global peak during partial shading conditions [156]. The advantage of the algorithm is that it is system independent and has fast tracking speed. Equation (23) is used to initialize the algorithm using the power fluctuation due to changes in irradiation.

$$\left| \frac{f(X\_{q+1}) - f(X\_q)}{(X\_q)} \right| > \Delta P \tag{23}$$

where *J (Xq)* is the output power of the PV panel. The algorithm efficiently differentiates the local and global peaks using the power mismatch.

#### *4.2. Circuit-Based Approach*

Power converters interface the generated power from the PV system to the grid or local loads. These power converters control the power flow and can enable MPPT controllers under partial shading at different levels of the PV system such as the PV cell, module or array [157]. Besides the power converters, changes in the PV system architecture and converter topology improve the performance of the PV system under partial shading. Some of the techniques the researchers implemented under this category are distributed MPPT, monitoring the bypass diode voltage, differential power processing, and power electronics equalizer, as described below.
