The intermittent, variable and unpredictable nature of solar energy lead to mismatch the rate and time of solar energy collection and its thermal applications. As a result, it is necessary to have energy storage unit which stores solar energy when the collection is in excess of load and discharges the same when the direct collection is inadequate. To store solar energy in sensible heat storage materials, pebble bed systems are simpler, economical in design and development as compared to latent or thermo-chemical energy storages. A number of studies are available on heating and cooling of pebble beds describing their parameters like pebble size/diameter, bed porosity, surface area, a shape factor of storage media/pebbles to observe the behavior and characteristics of storage devices. Many correlations are available to analyze the heat transfer coefficients, friction factors and pressure drops in between the solids and circulating fluids in pebble beds. The relations are of importance and best suited for energy storage system modeling.