The effect of metallic copper nanoparticles on the thermal efficiency of an evacuated tube solar collector was studied. Different volume concentrations of copper nanoparticles e.i. 0.01%, 0.02% and 0.03% were examined to explore the effect of nanoparticles on evacuated solar collector performance. The tests were performed at three volume flow rates of 0.6 L/min, 0.7 L/min and 0.8 L/min. The results demonstrate a 50% increase in the output temperature. Also, the heat energy incremented from 417 W to 667 W, which is equivalent to 34% area reduction for the same energy production. The remarkable enhancement in the heat removal factor to reach a value of 0.97. Copper nanoparticles played a significant role to increase both the absorbed energy and the removal energy parameters. Their maximum values were found for a volume concentration of 0.03% and at the volume flow rate of 0.8 L/min to be 0.83 and 21.66, respectively. Finally, environmental analysis is carried out to find the role of copper nanoparticles in CO2 reduction. The comparison between current results with reported results in the literature for other types of nanoparticles show the high potential of copper nanoparticles for solar collector applications.