This paper presents the design and simulation of an integrated photovoltaic terahertz antenna based on laterally oriented GaAs nanowire arrays. The proposed structure combines the NWA solar cells with a metal mesh antenna to enhance light absorption through the diffraction effects of the two-dimensional grating and the excitation of localized surface plasmons. The simulation results demonstrate that the integrated design achieves improved photoelectric conversion efficiency, peaking at a nanowire diameter of 150 nm. The antenna maintains effective impedance matching and radiation efficiency after integration, ensuring that the device is suitable for practical applications, including multifunctional, compact solar energy harvesting and communication systems.