We present a DC-DC converter for photovoltaic (PV) applications that is suitable for distributed power conversion obtained by transferring part of the electronics from the inverter to the module. The proposed circuit implements a high-efficiency four-phase interleaved boost converter employing relatively low-valued inductive and capacitive components. Its compact realization is made possible thanks to the innovative design of a dedicated integrated circuit (IC) embedding the power MOS switches and performing the converter control section as well as the Maximum Power Point Tracking (MPPT) algorithm. The solution is designed for a maximum delivered power of 300 W and to work with an MPPT voltage between 9 V and 36 V, with maximum allowed panel current of 9 A. The area of the complete printed-circuit board is 4 cm $,times,$7 cm. Experimental measurements show that the average power conversion efficiency is between 93% and 99% and that the MPPT efficiency is always greater than 99.7%.