I can’t find documentation or models online that compare different solar heating systems, all things being equal, to each other. I can only find 'Before & After' comparisons, 'With & Without', or 'Solar vs. Conventional'. For a solar hot water house heating system: Is there a conventional wisdom as to whether; a well insulated above ground heat storage tank, is more or less effective, than a buried below the frost line geothermal tank that would ‘preheat’ the water to about 55F? Presume same size house, collectors, degree days, sunlight, etc.