Assuming the conventional divisions of the semiconductor into depleted and neutral regions, it is shown that for an abrupt p-n junction with nondegenerate carriers a relation exists between the open circuit photovoltage and the PN product at the junction(PN)_{0}, which is valid for all signal levels. In the small-signal case this leads to the standard result. At intermediate levels a new relationV = KT/q (1 \pm m) \log_{e} ([(PN)_{0}]^{1/2}/n_{i})holds, the upper sign for p+-n junctions, the lower for n+-p junctions;m = (\micro_{e}-\micro_{h})/(\micro_{e}+\micro_{h}). At very high levels the photovoltage saturates toV = kT/q[log_{e}(M_{p}M_{n}/n_{i^{2}}) + m \log_{e}(\micro_{h}M_{p}/\micro_{e}M_{N})]. Since Mpand MNare the doping levels in the p and n regions, the first term is the diffusion potential and the second term will be positive for p+-n junctions and negative for n+-p junctions. These results compare satisfactorily with the available experimental data.