Minimizing the Side Lobe Level (SLL) and attain highest achievable Beam Collection Efficiency (BCE) is a critical goal for Solar Power Station/Satellite (SPS). If all antennas are uniformly excited then the main beam will carry only a part of the total energy due to the higher SLL. SLL is decreased and BCE is increased by adopting edge tapering for SPS. But edge tapering is a complex technical problem for SPS. So an optimization is needed between uniform amplitude distribution and edge tapering system. We have derived a new method of edge tapering called Isosceles Trapezoidal Distribution (ITD) edge tapering. Only a small number of antennas from each side of the phased array antenna are tapered in this method. ITD edge tapering is almost uniform so it is technically better. We have compared different amplitude distribution systems; uniform, Gaussian, Dolph-Chebyshev and the newly derived ITD method. The SLL reduction in ITD is even lower than those of other kinds of edge tapering. Therefore the amount of losing power in the SLL in ITD is lower. As a result the interference level becomes lower and BCE becomes higher in this method. The higher BCE and better SLL performance than those with unifonn distribution can be achieved in ITD with phase error and under unit failed condition.