To maximize and improve utilization of solar collector system, there is need to integrate the system with thermal energy storage (TES), this will increase the over all efficiency of the system and guaranty continuous supply of energy day and night. The performance of the TES depends on its thermal conductivity and this can be enhanced by introducing nanoparticles. Thus, this paper focus on the thermal conductivity enhancement of Cu and Fe nanoparticles dispersed in paraffin based suspension was investigated experimentally for utilization in solar collector integrated with TES. The enhanced thermal conductivity measurement was performed by transient hot disk sensor technique. The increment in thermal conductivity showed approximately linear progression with increase in percentage of mass concentration of the dispersed metal-nanoparticles. It was observed that the nanoparticle with lower thermal conductivity value (Fe- 80 W/m·K) at bulk enhanced the polymer matrix higher than the nanoparticle with higher thermal conductivity value (Cu- 401 W/m·K) at the bulk. The Cu and Fe nanoparticles, at mixing ratio of 1.5 by mass, increased the thermal conductivity of the paraffin based nanocomposites by 20.63 and 51.95, respectively when compared with the pure paraffin. The experimentally measured thermal conductivities of the Cu and Fe-paraffin nanocomposites were compared with some models and it was observed that they were under predicted. The thermal diffusivity and specific heat showed irregular increase and decrease with varying percentage mass concentration of the nanoparticles. The enhanced nanocomposite will be utilized as heat transfer medium in a solar collector system integrated with TES. © (2014) Trans Tech Publications, Switzerland.