Check out this Youtube TED video on a low-cost, high-tech refridgeration technology by Adam Grosser;
Crazy cool stuff - use a campfire as an energy source for cooling 3 gallons of water down to just above 0deg C, for 24hrs, in a 30deg C environment. Funny thing is that to figure out this technology, they had to get the entire thermodynamics dept at Stanford involved and used CFD (computational fluid dynamics) to regenerate the property tables for ammonia, discovering that the old ones were all wrong.....this is pretty freaky stuff.
So, we need something that takes energy from the sun to power an absorption chiller designed to cool down a house.
Alternative: Take the heat from inside the house (via the ERV/HRV), concentrate it to use as a heat source to power the absorption chiller to cool the house (again via ERV/HRV). Any losses in efficiencies (waste heat) go to the domestic hot water system. How cool would that be?
The Einstein refridgerator (an absorption chiller variant) uses no moving parts. A guy named M. McCulloch is involved with reviving this technology at Oxford university.
Now the search for practical units in the marketplace begins.