see **broken link removed**
Solar cell model is an illumination based current source with a parallel inherent diode that will forward bias if no load is applied. With no load, all generated current goes down the inherent diode.
Maximum available loading power point is when inherent diode just barely starts to conduct, taking about 0.3% of illumination generated current. The inherent diode obeys silicon diode temperature profile, meaning hot cell yields lower maximum voltage power point, like 0.4vdc, (less power output), cold cell yields higher maximum voltage power point, like 0.7 vdc (more power output). At room temp maximum power point voltage loading is about 0.45 to 0.5 vdc.