An experimental and numerical investigation on a paraffin wax/graphene oxide/carbon nanotubes composite material for solar thermal storage applications

•The thermal conductivity of the composite phase change material is 0.46 W m−1 K−1.•The composite phase change material contains only 2.2 wt% of hybrid graphene aerogel.•The solar absorptance of the composite phase change material is 0.952.•The composite phase change material has the advantages of good shape stability.•The light-to-heat efficiency of collector is 27% by numeral simulation.