Electrical energy produced by an energy harvester is stored on a temporary basis in an interim energy storage module before transferring it to a load. The current fed to the load is controlled so that a voltage limit of, for example, a capacitor in the interim storage module is not reached. By at least partially synchronizing the current consumed with the power produced, the capacity of the interim energy storage can be minimized, while still beneficially reducing fluctuations in the current. Current consumed may be determined by the use of a voltage to current look-up table, so that minimal communication overhead between the load and the power source is needed.