Solar flat plate collector (SFPC) is regarded as one of the best renewable energy devices to acquire hot water for domestic usage. Though its theoretical efficiency is projected at higher scale, its conversion efficiency is observed to be low due to various collector losses. Hence, to achieve improved performance of collector different techniques for heat transfer augmentation in circular pipes can be adopted. Among passive and active techniques available, passive is preferred over active due to economics and saving in exergy. Hence, in the present study absorber tube configuration is modified with internal grooves in the collector setup to enhance the rate of heat transfer. Also, fluids dispersed with metal oxide particles provide an increase in thermal conductivity such that ZnO-based aqueous EG mixture nanofluid is used as working medium to analyze the performance of collector setup. Also, the change in heat transfer rate and temperature profile of grooved tubes under forced laminar conditions for different working fluids are compared and reported. © 2017, Allerton Press, Inc.