The optimal energy transfer is investigated for a system combining a photovoltaic module, a bank of ultracapacitors and a resistive load. Each ultracapacitor element is modeled with an accurate multibranch circuit composed of resistors and nonlinear capacitors which permit to reproduce its non-ideal behavior. The charge/discharge of ultracapacitors fed with the photovoltaic module into the resistive load is numerically simulated for irradiance of 1000 W m(-2) and cell temperature of 25 degrees C. The energy and the durations of the charge/discharge cycles are sought according to the low and high voltage thresholds of the controller switches. The cycle efficiency is found in the range [86.5%, 93.5%] and the best time ratio cycle is determined. Finally, the voltage thresholds of the controller switch which enable to transfer the maximal energy within an hour are deduced. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.