This paper conducts theoretical study on employing phase-conjugation antenna array to beam microwave power from satellite to earth in the context of space solar power (SSP) applications. Our analysis reveals that, the phase-conjugation array must have aperture dimension greater than 1 km × 1 km in order to be applicable to practical SSP systems. Moreover, antenna array with such a large size does not behave as a conventional phased array, in that the power receiver on earth resides in the array's Fresnel region rather than far-field region.