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Broadband energy harvesting approach is crucial particularly for extracting electrical energy from ambient vibration which is random. The bandwidth of the harvested energy can be effectively improved by using multi-cantilever with different resonant frequencies, however, as the wider the bandwidth the resonant frequencies are far apart from each others leaving a huge drop of harvested energy between the peak frequencies which would not be practical for harvesting random vibration sources. This issue is being addressed in this paper to investigate the effect of different combinations of electrical connections of the cantilevers. An array of four similar piezoelectric cantilevers were mounted side-by-side to operate as a system in generating electrical output across frequencies range up to 500 Hz. The resonant frequency of each of the cantilever was varied by introducing a proof mass at the tip with an increment of 0.05 g. The bandwidth of the multi-cantilever system is effectively increases to 110 Hz with an open-circuit output voltage peaked at 6 Vrms and the voltage level gap is also improved when connected in series and opposing configuration.