This paper looks into how best to determine the parameters of an experimental monocrystalline photovoltaic (PV) module placed outdoor using Microsoft excel and single diode model. The non-stability of weather parameters added a little twist to the equation used. The average weather data used, as a fallout of weather fluctuations, are average solar irradiance G1 = 842.7Wm-2, and module temperature T1 = 52.35oC, the results obtained for the photocurrent (Iph), series resistance (Rs), shunt resistance (Rsh), open circuit voltage (Voc) maximum power point (Pmp), maximum power voltage (Vmp), maximum power current (Imp) and ideality factor (n) are 1.581 A, 0.71 Ω, 4.272 x 10-3 Ω, 9.9 V, 4.03 W, 14.4 V, 0.28 A and 201 respectively. However, saturation current (Io) could not be obtained using this method. When the parameters used were module temperature T2 = 27.58oC and solar irradiance G2 = 687.9Wm-2 were used, the I-V characteristics deviates totally from ideal situation and no model parameters could be deduced except Iph and Rsh which was found to be 1.262 A and 5.234 x 10-3 Ω respectively.
