The storage by ultracapacitors of photovoltaic energy is modeled in order to have an accurate and accessible model to integrate ultracapacitors into solar energy conversion systems. Ultracapacitors are modeled by a multibranch circuit representation composed of resistors and capacitors with variable voltage whose values are determined by an accurate characterization experiment. Moreover, all the elements of a typical photovoltaic energy conversion system are modeled by using the Matlab/Simulink software (solar radiation, photovoltaic panels, batteries and charges). The energy storage model by ultracapacitors is then validated by the good agreement of measured values taken in real conditions with the results provided by simulations. Finally, two examples are proposed and discussed: the determination of the storage duration of ultracapacitors versus solar irradiance and ambient temperature, and the integration of ultracapacitors in the electrical feeding system of a DC motor to reduce the electrical current peak of the battery at the start of the motor
