This article aims to derive the efficiency of the total antenna system that plays an important role in power transmission using microwave in the solar power satellite and other systems. In this study, the rectenna array is assumed as the receiving antenna, and the effects of the beam width of the transmitting antenna versus the size of the receiving antenna, the power density distribution on the receiving antenna, and the connection configuration of the receiving elements (rectenna) on the transmission efficiency, as well as the effects of the variation of the direction of the transmission antenna, are examined by numerical calculation. The connection configuration of the rectennas for improving efficiency, as well as the effect of reverse current prevention, are discussed. In the derivation of those items, it is shown that they can be represented by the intensity distribution and the area parameters (such as the total area and the area for each segmented receiving rectenna). It is then made possible to use the numerical integration in the calculation, and the desired result can easily be derived. The proposed method will be useful in the design and evaluation of the receiving rectenna for the solar power satellite, where a tremendous number of elements are installed.