The growing global energy demand and fossil resources depletion have triggered great interest in the use of renewable energy and low emission technologies. In this context, this work introduces a numerical simulation of an on-grid hybrid system of a combined heat and power unit (CHP) for residential and industrial micro-applications. The system consists of a 5 kW proton-exchange membrane fuel cell (PEMFC) coupled to a natural gas reformer, photovoltaic panels (245 W) and batteries (100 Ah each) connected to the grid through a bidirectional inverter. An energy analysis was carried out to validate the computational routine and assess the natural gas flow and the thermal and electrical efficiencies of the CHP unit. Afterwards, an economic analysis was developed to determine the consumers cash flow progression and the total cumulative cost of the system in an 2020-2040 horizon in order to investigate the influence of increasing natural gas and electricity tariffs, different system configurations, the number of consumers and the reverse metering factor from the grid. Different types of tariffs (conventional and alternative) and the possibility of cogeneration with the thermal rejection from the PEMFC were also evaluated. At last, an environmental analysis was developed to assess the contribution to the global warming potential of the micro-CHP. Paybacks between 6 and 20 years of system s operation were achieved for different combinations of the studied parameters considering beginning of operation in 2020. Additionally, great reductions in the total cumulative cost were obtained considering the predicted decrease in system s components acquisition costs for the next decades. Finally, reductions in CO2 emissions of up to 30 percent compared to those of the electricity from the Brazilian energy matrix and heat supply from burning natural gas were obtained when cogeneration from CHP unit was accounted to meet the consumers thermal demand.