This thesis investigates the use of Mie resonators implemented as Silicon (Si) nanodiscs to enhance optical and electrical performance of ultrathin Si solar cells. Through electromagnetic simulations nanodiscs were integrated on top of a Si substrate and their geometrical parameters were varied such that the solar weighted reflectance was minimised, improving the absorption. Compared to planar Si film, optimised nanodisc configurations revealed enhanced absorption in the 400 nm - 1100 nm wavelength range, and is most significant in the 400 - 500 nm range. Electric and magnetic field profiles as well as far field scattering plots revealed an increased forward scattering, contributing to the increased absorption. Electrical simulations of the Mie resonant solar cell showed a notable increase in the short-circuit current density and overall efficiency compared to a planar reference solar cell. The results highlight the effectiveness of Mie-type nanostructures for enhancing the performance of ultrathin Si solar cells for shorter wavelengths, and underscore the importance of balancing optical gains and electrical losses for better performance when it comes to longer wavelengths.