Question

why is I-V character of solar cell in the fourth quadrant?

Answer 1

The current in other Optoelectric devices like LED and photocells are flowing from a source of voltage to the devices but in case of solar cell, current flows from the cell to the load and thus current in circuit is taken to be in opposite ( or negative direction ). The voltage is still positive. Therefore, the fourth quadrant.

Someone else may provide you with a more explanatory answer.

Answer 2

Actually,in solar cells it do not need current for its operation.It can only supply the current to the load. At the same time the emf generated by the cell is positive. So we have a graph on 4th quadrant.

or

The current in other Optoelectric devices like LED and photocells are flowing from a source of voltage to the devices but in case of solar cell, current flows from the cell to the load and thus current in circuit is taken to be in opposite ( or negative direction ). The voltage is still positive. Therefore, the fourth quadrant.


or

Without illumination, a solar cell has the same I-V characteristics as a large diode. When the light shines on the cell, the I-V curve shifts in the fourth quadrant as the cell begin to generate power. The p side of the pn junction acts as positive electrode and the n side of the pn junction acts as negative electrode. Therefore there is flow of current from positive terminal when external resistance is connected.