The demand for renewable energy sources is limited by their inherent intermittent nature. The thermal energy storage technique overcomes this shortcoming by allowing storage of naturally occurring energy (e.g. solar) during "non-peak hours". The article presents an experimental investigation of the sparsely studied 'single medium thermocline' (SMT) based single tank sensible thermal energy storage (TES). The work aims to reconsider its potential by minimizing the fluid dynamic perturbations during the charging cycle which disrupt the stability of the thermocline leading to undesirable energy losses. The article discusses the effect of Atwood number (density stratification) and mean temperature on TES effectiveness as well as providing the appropriate thermodynamic insights. Implementation of the experimental procedures and strategies discussed in this article demonstrates a stable thermocline which persists for more than 6 h (hours) with minimal energy degradation. (C) 2020 Elsevier Ltd. All rights reserved.