**1. Introduction**

A Photovoltaic (PV) cell is a device that by the principle of photovoltaics effect converts solar energy into electricity [1, 2]. In a PV module, PV cells are connected in a series and parallel configuration, depending on the voltage and current rating, respectively [1]. In recent times PV based energy is gaining prominence due to the advances in the PV cells [3, 4], lowering PV cells cost [5], and government incentives [6–8]. Compared to any other renewable energy-based power source, PV is

considered portable and easy to use [5]. Hence, the PV based power source is used in a wide range of applications that include residential and commercial building, drones, vehicle, satellites, embedded systems, sensors and many others [9].

The PV-based power source is not ideal and performance can cause many anomalies [10, 11]. One of the most significant issues that affect PV modules performance is the shading caused due to clouds, physical objects, and living beings [10, 11]. Generally, there are two types of shading, complete shading and partial shading [12]. The complete shading occurs when the whole PV module is under the shade. If only a few of the PV cells are under the shade, it results in partial shading conditions. Both of these shading types reduce the power efficiency of PV modules. However, the partial shading condition can have much more severe after effects [13]. The current flow in a row of PV cells connected in series is governed by the PV cells that are affected by the shade [13, 14]. This phenomenon can lead to forward biasing of unshaded PV cells, leading to them consuming the power instead of generating it [13, 14].

Additionally, the partial shading condition can cause hotspot generation in the panel's neighboring PV cells [15–17]. This hotspot can even instigate a fire hazard [18–20]. Mismatch in the PV cells in the PV module can also create abnormalities like the partial shading conditions [14]. Hence, to prevent such a phenomenon from happening, the PV modules are equipped with bypass and blocking diode [2, 9, 21]. The bypass diode causes bypassing of the shaded or damage PV cells in the panel [22]. Simultaneously, the blocking diode prevents the current from flowing in the reverse direction in case of a mismatch in the output voltage, which can lead to forward basing of the PV cells [21]. Similarly, faults such as open and short circuiting of PV cells in the module degenerate the solar panel's performance [12].

Due to all these abnormalities that reduce the PV panel's performance, it is desirable to model a PV module that can emulate its electrical characteristics to derive a better way to tackle them. Also, equivalent modeling helps to better understand the PV panel characteristics before they are being deployed for real-world applications.
