This article proposes to use the idea of equivalent impedance to investigate the electrical
response of an array of piezoelectric oscillators endowed with distinct energy harvesting
circuits. Three interface electronics systems are considered including standard AC/DC and
parallel/series-SSHI (synchronized switch harvesting on inductor) circuits. Various forms of
equivalent load impedance are analytically obtained for different interfaces. The steady-state
response of an array system is then shown to be determined by the matrix formulation of
generalized Ohm’s law whose impedance matrix is explicitly expressed in terms of the load
impedance. A model problem is proposed for evaluating the ability of power harvesting under
various conditions. It is shown first that harvested power is increased dramatically for the case
of small deviation in the system parameters. On the other hand, if the deviation in mass is
relatively large, the result is changed from the power-boosting mode to wideband mode. In
particular, the parallel-SSHI array system exhibits much more significant bandwidth
improvement than the other two cases. Surprisingly, the series-SSHI array system shows the
worst electrical response. Such an observation is opposed to our previous finding that an SSHI
technique avails against the standard technique in the case based on a single piezoelectric
energy harvester and the explanation is under investigation.