ZJ - Solar Thermal Heat Conduction is different from Geo-Thermal.
Geo = Earth, Solar = Sun. I'm going to be using a big tank full of coils with a glass cover pointed directly at the Sun, which will heat the water. Since the tank is downhill from me, once the water is heated, it will begin to circulate on it's own (thermal conduction). The hot water will rise up the hill into the floor (or bypass valve), and the cooled water will flow back down into the tank to be reheated. (It's not actually water, it's an eco-friendly coolant material that I haven't found yet.)
As far as waterproofing, I'm going to use liquid membrane on the buried walls of the house, with drainage stone and sluice pipes at the lowest point of the foundation.
This stuff is the first thing that comes to mind:
Rubber waterproofing for foundations: ICF and standard concrete