Wave energy is among promising source of renewable energies. Compare to wind and solar power, wave energy provides energy with higher power density. Despite solar energy, wave energy can be harvested during all day long. So far, various techniques are presented for wave energy harvesting: a part of these techniques use the swing movement of the waves and others use wave turbines to produce energy. The wave energy harvesters are conventionally in the range of several hundred kilowatts, and often tens or hundreds of wave energy harvesters are connected together through a collector system to form a wave power plant. The wave energy harvesters can be interconnected via various collector systems including direct current (dc) and alternative current (ac) systems where can be connected in series, parallel, series-parallel and other types of interconnection configurations. As overhead power lines cannot be used in seas, the main advantage of dc collectors over the ac counterpart is the elimination of charging current that is particularly in underwater cables due to its notable capacitive feature. However, as the captured power from sea waves should eventually be injected into an ac power system, the use of high-power electronic converters is inevitable. The use of high-power converters forces technical and reliability issues. In order to select the appropriate collector system considering the charging current limitation in the ac systems and the limitation of use high-power converters in dc systems, in this thesis, dc collector systems are compared from the point of view of maximum energy delivered to grid and farm costs. In order to evaluate the systems from the point of view of the energy delivered to the grid and the final cost, the improved levelized cost of energy (ILCOE) index is introduced for wave power plants and used. In order to take into account the not supplied expected energy due to a failure, the reliability calculation of the system is perform and its impacts on the levelized cost of energy is appropriately modeled. Using this idea, a method is proposed that can be used to select the suitable collector system configuration for wave power plants. To verify the validity of the proposed method, the data of a power plant in California for 3, 15, and 29 megawatt capacities are used. … Keywords Renewable energies, Wave energy conversion systems, Buoy wave energy harvesters, Improved Levelized cost of energy, Markov model, Iran ports, Reliability.