Machine-History.Com

A standard air conditioning system uses a compressor to increase the pressure on the gas, forcing it into a liquid in the condenser coil. The change of state of the refrigerant starts to take place approximately 2/3rds of the way down the condenser.

A Solar Hybrid Air Conditioning System uses a different method. It uses the heat from the sun to superheat the refrigerant which enables it to begin changing state in the top 2/3rds of the condenser coil.

By using this method it reduces the superheat of compression required to achieve the cooling process in the conventional cooling system as well as utilizing more of the cooling face of the condenser coil.
See http://www.machine-history.com/Solar%20Powered%20Air%20Conditioning