Avaliação de sistemas fotovoltaicos conectados à rede através de figuras de mérito

Abstract

This work presents a qualitative and quantitative study of Photovoltaic Systems connected to the electrical distribution system of the local concessionaire, systems that have been installed and in operation in Maceió - AL for at least 12 months. Only systems with a DC-AC conversion device (inverter), of the same specification and manufacturer, were considered. The power that is supplied to the loads and the network is conditioned to the rated power of the inverter, because in optimal operating conditions the inverter is only capable of providing its maximum rated output power, regardless of the power of the PV generator in direct current connected to its entry, this condition motivated the realization of this study. Inverter dimensioning factor (FDI) is understood as the ratio between the nominal output power of the inverter (kW) and the power of the photovoltaic generator (kWp), this factor is very important when installing a photovoltaic system, in order to have the best energy response. This factor depends on the operating conditions, on the seasonality, consequently, on the irradiation levels of the generator installation location. An optimized FDI implies an optimized costbenefit ratio and an optimal energy generation. The calculation of the figures of merit is the instrument of quantitative evaluation of these systems and that allows to evaluate the performance of a system based on the design and installation conception, in addition to identifying the particularities and points that make one system stand out in relation to the other. Four systems (A, B, C and D) were evaluated, each system with a different FDI. It was noticed that the systems with azimuth deviation closer to 0º had higher overall productivity. It was noted that the lower the FDI, the greater the capacity factor in periods of low irradiation. However, when observing the productivity of systems with high load, it is noted that there is a power reaping provided by the photovoltaic generator at the inverter output, this is due to the low FDI for local irradiation levels which ends up directly affecting the global productivity. It was then realized by the results of the 12 months that there is a signal that there is an optimum FDI for each system for each period of the year and that variations in the FDI can represent productivity gains, consequently of energy generated, making the MPPT of the inverter always operate in an optimized range.