Studies and research on the thermoelectric power generator which converts heat into electricity had given attention ever since the Seebeck effect was discovered by Thomas Seebeck in 1821. This effect inspires a temperature difference is executed between two junctions, the potential difference will occur on the voltmeter. This voltage difference is proportional to the temperature change. However, the main limitation for technological development and application was the low conversion efficiency because it depends on the difference in temperature between the heat source and the heat sink. The power and conversion efficiency for a thermoelectric module is the objective of this study to be enhanced by maximizing change in temperature using a direct evaporative cooler as a heat sink of TEG. The experiments and numerical analysis were carried out to study the influences of the main factors of the evaporative cooler such as the air velocity, the flow rate of water consumption, and the staging of cooling pad on the power and efficiency of the thermoelectric generator. The parameters were found to significantly affect the cooling capacity and the power and efficiency of a thermoelectric generator. A search for optimal conditions such as air velocity, water consumption, and cooling pad staging of 3m/s, 3.2g/s, and three-stage was carried out as a result of the maximum power output and the corresponding thermoelectric generator conversion efficiency of 37.2W and 6.08%, respectively was found at approximately 150°C temperature change between the hot and cold surface. Validation of the numerical results with those from the experimental results was also presented; the predicted and experimental results would be in good agreement with less than 2 % error.