A simulation model for solar assisted shallow ground heat exchangers in series arrangement

Results show that solar heat injection into the ground decreases the required borehole length by a greater amount for a field of shallow boreholes than for a one deep borehole configuration. Minimum fluid temperatures returning to the heat pump has a significant effect on the required borehole length for both a one borehole configuration and shallow bore fields (50% and above from 0 °C to −5 °C). For networks of shallow boreholes, borehole spacing has to be determined carefully as the total required length of shallow bore fields can be as short, or even shorter, as a one borehole arrangement.