This paper presents the Newton-Raphson discrete equivalent circuits for the diode. The models are derived succinctly, proved theoretically, and verified computationally. The Newton-Raphson discrete equivalent circuits are the large-signal terminal models for the diode, from which simplified diode equivalent circuits and diode small-signal equivalent circuits can be easily deduced. The standard circuit model for the photovoltaic module is a current source in parallel with a diode and a shunt resistor and in series with a resistor. The proposed diode models make the solution of the photovoltaic module natural, accurate, simple, reliable, and non-software dependent.