Ammonia is an alternative renewable green fuel with significant potential for addressing climate change concerns. Blending ammonia with methane has emerged as a viable strategy to improve the laminar burning velocity of ammonia. In this study, we propose a mechanism for methane/ammonia combustion, comprising 31 species and 131 chemical reaction steps, and investigate the emissions of CO and NO, along with electrical power output and energy efficiency of a micro-thermal photovoltaic (MTPV) system fueled with premixed ammonia/methane/oxygen. Three key parameters are identified as: 1) the inlet mixture flow velocity, 2) the CH₄ mole fraction blended ratio (ξCH₄), and 3) the material of the micro-combustor. The MTPV system achieves its highest energy efficiency (5.8 %) at an inlet velocity (vin) of 2.3 m/s, and reaches its maximum electrical power output (6.9 W) at vin = 7.2 m/s. Further, increasing ξCH4 can enhance electrical power output (ξCH₄ = 0.9 yields 1.37 W more than that at ξCH₄ = 0.1). Finally, altering the micro-combustor material is shown to have little effects on electrical power output, NO emissions, and energy efficiency. However, the MTPV system made of quartz is found to reduce CO emissions by 15 % and 12 % in comparison with those systems made of Sic and steel, respectively.