<P> However, when R is large it's better to solve the original equation numerically . </P> <P> The general form of the solution is a curve with I decreasing as V increases (see graphs lower down). The slope at small or negative V (where the W function is near zero) approaches − 1 / (R S + R S H) (\ displaystyle - 1 / (R_ (S) + R_ (SH))), whereas the slope at high V approaches − 1 / R S (\ displaystyle - 1 / R_ (S)). </P> <P> When the cell is operated at open circuit, I = 0 and the voltage across the output terminals is defined as the open - circuit voltage . Assuming the shunt resistance is high enough to neglect the final term of the characteristic equation, the open - circuit voltage V is: </P> <Dl> <Dd> V O C ≈ n k T q ln ⁡ (I L I 0 + 1). (\ displaystyle V_ (OC) \ approx (\ frac (nkT) (q)) \ ln \ left ((\ frac (I_ (L)) (I_ (0))) + 1 \ right).) </Dd> </Dl>

What is open circuit voltage in a solar cell