The role of thermal energy storage (TES) is critical in addressing the intermittency of solar energy, enabling continuous power generation in solar thermal power plants. The present paper evaluates TES options for a 20 kWe Organic Rankine Cycle (ORC) based thermal power plant that is to be commissioned in Sri Lanka, developed under the Innovate UK project RESORCS (Off-Grid Renewable Energy Production and Storage). The study explores sensible heat, latent heat, and thermochemical storage technologies, with a focus on commercially available options such as molten salts, water-based systems, and phase change materials (PCMs). HiTEC salt and Na-Li nitrate eutectic salts are optimal TES solutions for low- to medium-temperature applications, offering low melting points, high specific heat capacities, and robust energy densities. Performance analysis at 200 °C and 220 °C confirms their thermal stability and efficiency. Preliminary calculations support 24-hour plant operation but emphasize the need for further modeling to account for system thermal losses. This analysis provides a framework for selecting an efficient, cost-effective TES medium to ensure reliable off-grid energy production with an ORC system.