As the Solar Focus panels are new (and untried for this purpose), we did a dry mock up of how the panels would be plumbed on the south wall of our house, using 40mm pipe joints. On the upper wall, we have 2.55m of clear space between the window and the RW downpipe, so need to work out exactly how the panels will fit, along with all the joints, which add 65cm to the width of the actual panels. I am doing an ArchiCAD drawing of the arrangement - the total width of both panels including fittings will be 2.25m, but another arrangement could be to space the panels either side of the window, so that I can reach the air release valve without needing a ladder.
David Atkins mooted the idea that with enough of Solar-air panels like these, you would not need slinkies or borehole at all to support a GSHP, as solar air-panels can be more effective than ground loops, or can be very effective supplements to a reduced cost ground loop, as indeed we are intending to find out.
There would be many variables such as glycol flow rate, and how many degrees of frost the panels can endure, if the GSHP pushes glycol round even colder than a winter's night air. (He has seen collectors encrusted with ice, but safe). As one most frequently requires heat at night, a system drawing heat from a buffer solar water tank (that is warmed in daytime by the solar-air panels) would smooth out day-night fluctuations. It's worth modeling on the computer, if not in real life.
The water in the buffer tank wouldn't freeze, as there comes a time in winter when the GSHP is getting more of its heat from the deep ground (which is 10-12º) and I have never seen the outgoing glycol to be less than -1º for short periods. Ice needs a lot of latent heat to freeze, and then doesn't expand until it gets below -4º.