This paper uses an ant system (AS) meta-heuristic optimization method to solve the problem of structure optimization of power cellular systems. We consider the case where redundant cells are introduced to achieve a desirable level of reliability. The cells of the system are characterized by their cost, technology, capacity and availability. The reliability is defined as the ability to satisfy the consumer demand (battery load) which is represented as a piecewise cumulative load curve. The proposed meta-heuristic seeks for the optimal configuration of series-parallel systems cells in which a multiple choice of cells are allowed from a list of different technologies are available in the market. Our approach has the advantage to allow cells with different technologies to be allocated in parallel-series. To allow fast reliability estimation, a universal generating function method is applied.