At no load the solar cell will be operating in open circuit condition. If there is internal shunting resistance it will slightly load the solar cell. This shunt resistance must be high enough such that it will not cause an appreciable loss of the photo voltaic power.
Equivalent resistance of the circuit, Req = (12||18) + 8 Req = 7.2 + 8 Req = 15.2 ohm Source current = current through 8 ohm resistor, I = Vr/R8 I = 20/8 I = 2.5 A Supply votage V = I*Req V = 2.5*15.2 V = 38 V
EXAMIANS