2.1.1. SDM

Figure 1a mentions the equivalent schematic of the SDM. The output voltage and current are *V* and *I*, respectively, and the electrical expression of *I* is shown below [34,35].

$$I = I\_{\rm ph} - I\_{\rm sh} - I\_{\rm sd} = I\_{\rm ph} - \frac{V + IR\_{\rm s}}{R\_{\rm sh}} - I\_{\rm ssd} \left[ \exp\left(\frac{q(V + IR\_{\rm s})}{nkT}\right) - 1\right] \tag{1}$$

where *Iph*, *Ish*, *Isd*, and *Issd* represent the photogenerated line current, shunt resistor line current, diode line current, and diode saturation current, respectively. *Rs* and *Rsh* represent the series resistance and branch resistance, respectively. *n* represents the ideal factor. *T*, *k*, and *<sup>q</sup>* represent the Boltzmann constant (1.3806 × <sup>10</sup>−<sup>23</sup> J/K), absolute temperature, and unit charge (1.6022 × <sup>10</sup>−<sup>19</sup> C).

**Figure 1.** PV models' circuits: (**a**) SDM; (**b**) DDM; (**c**) TDM; (**d**) PV module.

The above demonstrates that accurate modeling requires estimating the values of *Iph*, *Issd*, *n*, *Rs*, and *Rsh*.
