METHODOLOGY FOR COMPARING THE PV PLANT TOPOLOGY BASED ON AVAILABILITY AND PRODUCTION COSTS USING RELIABILITY – CASE STUDY VILLA LOBOS PROJECT IN SAO PAULO, BRAZIL Sergio Shimura, Roberto Silva Simplicio, Rafael Herrero Alonso, Cesar Biasi de Moura, Marcelo Knorich Zuffo, Roseli de Deus Lopes Laboratorio de Sistemas Integraveis da Escola Politecnica – Universidade de Sao Paulo Av. Prof. Luciano Gualberto Trav.3 N.158. CEP: 05508-900. São Paulo - SP - Brazil ABSTRACT: The purpose of this work is to develop a methodology for comparing plant configuration (number of inverters, string size and cabling configuration) based on the LCOE (Levelized Cost of Energy) and availability. The model used in this methodology includes the implementation and the operation costs (repair parts and labor for corrective and preventive maintenance), reliability model of each component of the power plant, from the PV modules to the main disconnect switch; spare parts management; statistical models for time to repair, repair team and component costs and delays; and finally, the production yield available for each component. Three different configurations are analyzed: one with centralized inverter topology and two with decentralized inverter topology. A reliability block diagram model was built for each configuration and simulation results on these three options are presented to demonstrate the effectiveness of the methodology. Keywords: Reliability; Large Grid-connected PV systems; System Performance; PV System; Economic Analysis 1 INTRODUCTION Investment funds in energy sector uses a simple model to estimate the LCOE as shown [1]: LCOE = [CAPEX + PV (OPEX)] / PV(PE) Where: LCOE: Levelized Cost of Energy (US$/kWh) CAPEX: capital expenditure (US$) PV(OPEX): Present Value of operations & maintenance for the whole life of the PV Plant (US$) PV(PE): Present Value of total delivered energy (kWh) For the initial investment (CAPEX) the approximate cost per peak power is multiplied by the total peak power of the PV plant; the plant operation costs (OPEX) are based on a fixed percentage of the total PV plant cost, a number between 0.8 and 1.2% and the total energy produced by the PV plant is simply the result of the maximum possible output per year (24h/7d operation) times the capacity factor. However, the reliability and availability of the system plays an important role in this estimation and it is usually neglected. Recent studies of PV plant reliability uses a simplified reliability model (constant failure rate) considering the impact of main components only [2], while other includes the Reliability Block Diagram models of main components such as PV modules, switches and inverters based on actual field data [3]. A combined study of the parts failure effects on the cost of operation and production opens a large field of investigation. This paper proposes a model that addresses the issues mentioned above (more specifically the use of simplified models and the lack of reliability and financial combined analysis) with the purpose of comparing three different PV plant designs. This study is based on a detailed description of all components: reliability model, time-to- repair and delay times (parts acquisition), production, parts and man power related costs and implementation costs - civil work and material, related services, SCADA (supervisory control and data acquisition system) - and commissioning. In order to obtain realistic results, an one year production analysis was done previously to generate the total plant production based on its location; the reliability models were based on interviews; manufacturers certificate; recent reliability data and the IEEE 493 Gold book [4]; and finally, parts and man power costs, based on the local data survey. 2 METHODOLOGY The process starts by building the Reliability Block Diagram based on the complete one-line diagram and the total energy production simulation for one year. Each reliability block then must be fed with the correspondent reliability models, repair time models, delays, maintenance information, repair and maintenance assigned crews and related costs. Also, the production yield must be provided. The energy production simulation was done with the PVSyst TM [5] and the reliability analysis, with the ReliaSoft BlockSim 9 TM [6]. CAPEX estimation was based on implementation costs of similar structures built in Brazil in 2014 [7] and [8]. For the present value calculation the following production losses were considered: 1% for years 1, 2 and 3; 0.7% for years 4 through 12 and 0.6% for years 13 through 20. 2.1 One-line Diagram All three one-line diagram, centralized inverter, four inverter and string inverter topologies, are complete and follows the standards applicable to the Brazilian interconnect regulations [9] and [10]. 2.2 Energy Production Simulation The PV module layout is exactly the same for all three configurations. The plant was modeled in 3D with the surrounding buildings and simulated in the actual location (23°32'38"S 46°43'54"W, 730m altitude). The result of the production simulation is summarized in Figure 1. The total energy production for one year is 636513 kWh with a final capacity factor of 16.3%, corresponding to 3.9 hours of operation at full throughput per day. This information is used by the BlockSim TM model in the Phase Diagram where the operation with full production corresponds to 4 hours and no production to 20 hours. 29th European Photovoltaic Solar Energy Conference and Exhibition 2674