An integrated model for designing a solar community heating system with borehole thermal storage

Borehole thermal energy storage (BTES) is found to be a favorable method for storing a large amount of thermal energy, and suitable for seasonal solar thermal storage, especially for large communities. Drake Landing Solar Community (DLSC), built in 2006, is the first such solar community in Canada. DLSC has achieved a 97% solar fraction after five years of operation. Although the DLSC project has been a success technically, the cost of the system is not attractive. In this study, an alternative design approach for a similar community is presented. The primary goal is to develop a system that not only achieves similar or better performance but also costs less. TRNSYS 17, along with a novel custom BTES component, is used for the system design and simulation. With the alternative design, the annual community thermal load of 2350 GJ is mostly met by solar thermal collectors via BTES and after five years of operation a 96% solar fraction is predicted. The simulation results are compared with published results for DLSC. It is estimated that the proposed system offers a 19% saving in initial cost in addition to reductions of BTES area of 38% and solar panel area of 25%.