摘要： This paper examines the technoeconomic optimization of the size of valve-regulated lead acid-type battery energy storage systems (BESSs) in order to minimize the total annual operating cost of a grid-connected photovoltaic BESS within the framework of system operational constraints, using the improved harmony search algorithm. The electricity cost is calculated using time of use pricing, where the price of energy varies according to the load demand. The concept of feed-in-tari? is discussed, where power can be bought from and sold back to the grid. A sensitivity analysis is performed for three cases: without storage, with storage and without peak load shaving, and with both storage and peak load shaving. The total annual operating cost of the system is calculated for all three cases and cost savings are compared. The simulations, performed with MATLAB, show a good optimization performance.