DC-DC converter reducer and elevator, CC-CC conversion method, and photovoltaic plant that incorporates said converter. Converter (10) and method of converting direct current to direct current with reduction capacity and current rise, which incorporates a recovery circuit that uses the energy stored in parasitic inductances of an autotransformer (A), transferring it to an auxiliary capacitor (Cs), and partially to the output capacitance (Coss), when opening an input switch (S). It is thus possible to use the parasitic energy of the autotransformer (A) advantageously, achieving an optimized performance, for applications without the need to incorporate galvanic isolations, in addition the topology and operating mode favors achieving a rapid dynamic response and smooth switching. The converter and its associated method can be applied both to photovoltaic systems for serial connection of panels and portable devices powered by batteries, LEDs, etc. (Machine-translation by Google Translate, not legally binding)