This paper presents a methodology to determine and select a suitable excitation capacitance value for a winddriven self-excited reluctance generator (WDSERG), which would produce a constant output voltage under changing wind speed and connected load. A steady state mathematical model of WDSERG is developed from the dynamic model of self-excited reluctance generator (SERG) and phasor diagram. This model is used to develop an algorithm that searches for the optimum excitation capacitance which produces a desired output voltage level for any given wind speed and load within the operating limits of the WDSERG. Different scenarios of variable speed, load and power factor are considered and an optimal capacitance value is determined and selected for each cases. Published experimental data was utilised to validate the developed model. The results show that there is a distinct capacitance value that would produce a constant output voltage under any given operating conditions of wind speed and terminal load. The procedure presented can form a basis for the design of a variable excitation capacitor to maintain a constant output voltage under varying wind speed and load, which will invariably offer an effective and low-cost solution for output voltage control of WDSERG. (C) 2016 Elsevier Ltd. All rights reserved.