Equivalent Circuit of Solar Cell

The I-V characteristic given in Eq. (5) is derived for ideal condition, considering the internal series resistance of the cell as zero and shunt resistance as infinite. In actual practice, however, both have finite values, which would alter the I-V characteristics. The ideal and practical equivalent circuits of the solar cell are shown in Fig. 1.5. In practical cells I_sc is no longer equal to light generated current I_L but is less by shunt current through R_sh. Further, an internal voltage drop of IR_S is also included in the terminal voltage.

For a typical, high quality, one square inch silicon cell, R_S = 0.05 to 0.10 Ω and R_sh = 200 to 300 Ω.

Fig. 1.5: Equivalent circuit of solar cell (a) ideal, (b) practical