A solar cell of area $1.0\:cm^{2},$ operating at $1.0$ sun intensity, has a short circuit current of $20\: mA$, and an open circuit voltage of $0.65\: V$. Assuming room temperature operation and thermal equivalent voltage of $26\: mV$, the open circuit voltage (in volts, correct to two decimal places) at $0.2$ sun intensity is _________.