Análise comparativa de eficiência e custo-benefício em microgeração fotovoltaica: um estudo de caso das topologias microinversor e inversor string em Maceió-AL

Abstract

This work presents a comparative techno-economic analysis between string inverter and microinverter topologies applied to photovoltaic microgeneration systems installed in the city of Maceió, Alagoas, Brazil. The main objective was to evaluate the energy performance and cost-benefit relationship of two photovoltaic conversion architectures, considering systems with the same installed capacity, both composed of five 630 Wp modules, totaling 3.15 kWp. The methodology was based on the monitoring of two real photovoltaic systems, mainly differentiated by their inverter topology: one system with a string inverter and another with microinverters. The analysis was carried out using direct current power data collected from the manufacturers’ monitoring platforms, considering two monitoring windows: from October 9 to October 16, 2025, and from January 7 to January 21, 2026. The results showed that, over the consolidated period of 23 days, the microinverter system generated 371.405 kWh, while the string inverter system generated 324.513 kWh. The accumulated difference was 46.892 kWh, representing an overall gain of 14.45% for the microinverter topology. This superior performance is associated with the distributed MPPT architecture, which reduces the impacts of partial shading, module-level variations, and possible electrical mismatch. In the financial analysis, commercial cost data updated in May 2026 were applied to the energy results obtained during the monitored periods. The string inverter system presented a CAPEX of R$ 5,298.00, while the microinverter system presented a CAPEX of R$ 5,969.44, resulting in an additional investment of R$ 671.44. Considering the observed average additional generation and the reference electricity tariff of R$ 1.11/kWh, the differential payback was estimated at approximately 9.7 months. It is concluded that, for the analyzed case study, the microinverter topology presented better technical performance and economic feasibility, especially in urban environments subject to partial shading, module mismatch, and the need for individualized monitoring.