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The I_LG and I_sc are directly proportional to solar irradiance and temperature which can be expressed as below [15],

(1.14)

(1.15)

where, G_stc and G are the standard and actual irradiance in W/m². Similarly, the open-circuit voltage is also varying as function of irradiance which can be expressed as,

(1.16)

The V_oc equation is a non-linear transcendental equation and also need to be solved using numerical methods for determining the parameters under dynamic condition. The procedure for obtaining this value using GS or NR technique is similar as that of five parameter estimation of SDM of SPV. For a given operating temperature, the I_sc and V_oc can be evaluated using the following expressions:

(1.17)

(1.18)

Where T_stc and T denotes the standard and actual operating cell temperature in K. On the other hand, the light generated current as a function of temperature can be determined using (1.4) and is rewritten as,

(1.19)

For any operating temperature and irradiance, the value of I_LG, I_SC and V_oc can be estimated using the equations (1.20) to (1.22) as below,

(1.20)

(1.21)

(1.22)

The thermal voltage (V_t) as function of cell temperature can be represented as,

(1.23)

The diode dark current also called reverse saturation current as a function of cell operating temperature and irradiance can be represented using (1.6) and (1.23) as,

(1.24)