I have been thinking, reading, studying, experimenting for over a year now, and I am convinced that the most efficient form of "solar" airconditioning would be the use of a ground source, or "earth coupled" system, importantly WITHOUT THE HEAT PUMP, and combined with a desiccant wheel to remove the insensible load.
With ground temperatures usually below 18 or 19 C, and a target temperature of 23-24C, there should be enough diferential for a decent heat exchanger, especially if the air has been dehumidified first....
I've had the devil's own trouble finding someone to sell me a desiccant wheel cassette, and in getting specs for plate and frame heat exchangers.
The other info about pipe fields etc is readily available.
If anyone else is interested, I'd be keen to pool my work.