In this paper, a single inductor-single sensor based photovoltaic optimizer with an optimal current point tracking strategy is proposed. With only one inductor, one sensor and one MPPT unit, this optimizer can not only make all submodules output their individual maximum powers, but also utilize the least components compared with current solutions, greatly reducing the size and cost of photovoltaic optimizer and increasing the integration level. The effectiveness of the proposed solution is verified by both simulation and experiments.