A pilot scaled solar collector was used to compare different heat transfer fluids, with a radiation source of a 1000 W halogen lamp, real time acquisition with a multiplexer and a Pt100 temperature control. The heat transfer fluid studied was a mixture of water and ethylene glycol 30% (w/w) with three different concentrations of nanographene (0.05, 0.08, 0.10 wt.%). The concentration that showed better results was used in a real test situation, without addition of dispersive agents. For both situations we report a higher efficiency of the collector, without visible clogging problems, due to the low nanomaterial concentration used.