Looking for some input on a design that I am kicking around. Tried finding some detailed information from other similar installed systems but no luck so far. Hoping someone here has some insight on something like this.

House:
Located in Southern Maine, 1700 sqft ranch which includes the soon to be finished basement. Retrofitted sub floor radiant heating system for basement and first floor. R-19 walls and R-60 attic. House has attached garage on south side, no south facing roof as ridge line is almost due north - south. House was constructed in 1996. Have 108' well.

Current heating system is a 2004 oil fired boiler, also get my hot water from the boiler. Efficiency of boiler is 86% based on the last service done fall 2014. I will be completing the radiant retrofit in time for next winter.

System I am trying to find more info on:
 - 3 ton Geothermal system also provides hot water
- Evacuated tube solar collectors plumbed into hot water storage tank and heat sink. With temp regulating valves on hot water tank to properly divert water from collectors to heat sink when it hits 120F Heat sink is constructed out of Concrete with loops through out. One loop for the solar hot water system and another loop for the geothermal system.
- Heat sink would be buried 12' deep, ground temp is about 45 F at this point.

Also will install thermocouples in various locations in the system to monitor and troubleshoot with the whole system tied to PLC and HMI for house monitoring and zone temp control.

Questions I have:

- Will this system work? Would like to have enough heat in the heat sink to provide 75% of the heating needs at night and also be big enough to dump the heat from the evacuated tube collectors in the summer when I don't need as much heating.
- How big would the heat sink have to be? Was doing calculations based on 25'x25'x3' for the heat sink but realize that this is probably overkill? Foot print isn't an issue.
- Would an electric hot water tank with the solar collectors be better than using the geothermal for hot water?
- How many 30 tube evacuated tube collectors would be needed for the appropriately sized heat sink?

I have gotten quotes for drilling my well deeper and going with a standard geothermal system but it was way to expensive for the well and no guarantees my well water would still be potable when it was completed. Issues with brackish water in our area.

Thanks for any help and info!