The micro combustor is a key component of a micro thermophotovoltaic (TPV) system. In order to maximize the power output, a high wall temperature and uniform distribution along the combustor wall are desirable. Compared to the cylindrical structure, a modular TPV system has been developed with the advantages of easier fabrication and assembly. Three kinds of micro combustors with widths of 1.0 mm, 1.5 mm and 2.0 mm have been experimentally studied. The results indicate that the wall temperature decreases with the increase of width due to the weakened heat transfer between the wall and the hot gases. Other parameters affecting the performance of the micro combustor have also been studied. For the first time, a SiC porous foam was inserted in the micro combustor to enhance both the preheating of the inlet mixture and the heat transfer between the hot gases and the wall, thereby increasing the wall temperature. An increase of 80-90 K has been obtained along the wall of the micro planar combustor with SiC as porous media. This enhanced performance translates to an increase of 33% in radiation energy density.