This article investigates the use of off-the-shelf (OTS) diodes as opening switches in a 500-kV nanosecond pulsed power generator. A 40-J test bench based on a saturable pulse transformer and a primary thyratron switch is designed to evaluate the performance of the OTS diodes in comparison with standard semiconductor opening switch (SOS) diodes A distinguishing feature of the proposed circuit is the adjustability of the output pulse energy, which is achieved using flat hysteresis loop magnetic cores and variable reset magnetic field. The study confirms the operation of OTS diodes as an opening switch, although highlighting differences in the reverse current conduction that affect the generated voltage pulse characteristics. Based on the successful operation of the OTS diodes, a 500-kV pulsed power generator using an OTS Solid-State Opening Switch (GO-SSOS) is developed. The GO-SSOS provides output voltages of 100–500 kV across resistive loads from 50 Ω to 1 k Ω , with a pulse width of about 100 ns and a rise time of less than 40 ns. The generator achieves a peak power of 335 MW and demonstrates an overall energy efficiency in the range of 30%–70% depending on the load. Operation at a pulse repetition rate of 60 Hz is presented, showing a good reproducibility of the pulses with an amplitude and duration deviation of about 2% and 10%, respectively. No degradation of the OTS diodes has been observed after the tests (more than 1000 pulses). As an example of the possible applications of the GO-SSOS, corona discharge in the air is performed, also proving the stability of all the systems under conditions of strong electromagnetic interference