Developing a Solar Energy System Using Seasonal Earth Thermal Storage (SETS) at the Smithfield Academy (Hatfield, MA)

An investigation was conducted to determine the performance of a solar system which uses earth as a seasonal energy medium. A comprehensive computer analysis based on our experimental data showed that the performance of the system exceeded the performance of the same system without seasonal storage capability by a minimum of 10%. The results also showed that it is practical to store solar energy all summer and that it will still be available for heating the building as late as November. An economic analysis was carried out using simple payback and life cycle costing and assuming a discount rate of 9.1% and fuel inflation rate of 12%. The analysis showed that the payback time will be 12.5 years. Simple guidelines for the design of similar storage facilities have been prepared. These guidelines discuss the type of system suitable, the need for top and side insulation over the storage volume, and steps for the design of different system components.