In the inverted heterostructure photodiodes(IHPs), the strong polarization effect at the interface of the AlGaN/GaN heterostructure influences UV/Solar rejection ratios of this type of structure. In this paper, the total effect of polarization is divided into two parts: the polarization and dipole terms. Based on the model of GaN/AlGaN/GaN IHPs, the influence of dipoles on the UV/Solar rejection ratios is analyzed. The results show that when dipoles are considered, UV/Solar rejection ratios of photodetectors are about three orders of magnitude, which agree with the experiment of Tarsa. The influence of dipoles should be considered in the IHPs.