Dielectric properties and ac electrical conductivity (sigma(ac)) of Au/PVA(Co, Zn acetate)/n-Si and Au/PVA(Ni, Zn acetate)/n-Si Schottky diodes (SDs) have been investigated in dark and under illumination by using experimental capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements at 1 MHz and room temperature. Experimental results indicate that the change in dielectric constant (e), dielectric loss (epsilon ''), loss tangent (tan delta), the real (M') and imaginary (M '') parts of electric modulus and ac electrical conductivity (sigma(ac)) with illumination were found to change linearly with illumination level (P). On the other hand, the epsilon', epsilon '', tan delta and sigma(ac) vs P have positive slope while the M' and M '' vs P have negative slope. Such behavior of dielectric properties and sigma(ac) can be attributed to illumination induced electron-hole pairs under illumination effect in the depletion region of SDs. The obtained results under illumination suggest that these devices can be used as a sensor in optical applications.