Computational prediction of significant efficiency gain through multi-tank modular heat storage for solar thermal systems with variable-temperature input profile

•Short term temperature fluctuations are mitigated with sensible heat storage.•Experimentally validated numerical scheme is employed for thermal analysis.•Multi-tank modular storage provides significantly higher round trip efficiency.•Application on a PTC output data shows remarkable improvement of efficiencies.•Exergetic efficiency is more enhanced; hence application is apt for thermal power towers.