Solar thermal collectors (STCs) are pollution-free and can be found in many parts of the world makes them a possible solution for both heating and cooling environments. The optimization of energy conversion is dependent on the improvement of the thermal efficiency of STCs. In light of this, the objective of this article is to present an overview of the utilization of carbon nanotubes (CNTs) for the aim of improving thermal performance in evacuated tube and flat plate solar thermal collectors from a technical standpoint