Determination of Optimal DC/AC Ratio for Grid-connected Photovoltaic Systems

Abstract

Suitability evaluation of a location for solar power generation plant installation requires long-term measurements and calculations. Since the energy production values and project power of solar power plant (SPP) directly affect the return period of the project cost. It is of considerable importance to make the calculations correctly. The effects of the DC/AC ratio, determining in an inverter selection, is a crucial parameter in determining the sizing of SPP. In this study, a model was used to find the closest estimation values. Irradiance values coming to SPP in Balıkesir/Turkey were simulated and DC energy at the inverter input was calculated. The results obtained from the calculation were compared with actual production values. To determine the optimum DC/AC ratio of the existing installed SPP system, calculations were made with two different methods. Energy production estimation values are calculated for different angles and DC/AC rated inverters. It is vital that the SPP consists of two groups with different directions and the same capacities in terms of comparing the accuracy of the calculation. Energy production calculations, including the hourly meteorological data and catalog values of the system, in the developed model are desired to provide the closest prediction values for energy production of the real system. The optimum DC/AC ratio also varies depending on the coordinates, direction and angle of the PV system. As a result, it has been observed that the direction and location of the PV system affect the selection of inverter power. Thus, it is important to calculate this ratio for efficient working conditions of each system. Optimal values of ratios and efficiencies for Groups 1 and 2 are calculated as 1.28, 1.35, 91.55% and 90.62%, respectively.

Keywords

• Clipping
• DC/AC ratio
• Grid
• Performance analysis
• Sizing ratio
• Solar energy

References

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