Solar AC?

Wow! They are using solar for cooling. That is some space age stuff. Um....no. In 1878 a French inventor named Mucot made ice with solar thermal to win a gold medal at the Paris World Exposition. There are centuries-old solar cooling concepts used in modern applications such as passive solar, evaporative cooling, Trombe walls and solar chimneys. Recent technologies include absorption cooling, adsorption cooling and PV assisted air conditioning. The most recent innovation, and what I will briefly discuss,  is solar hybrid air conditioning. This technology uses evacuated tube solar collectors, the most efficient solar collectors,  to increase the temperature and subsequently the pressure of the refrigerant after it leaves the compressor. This leads to more BTUs of cooling at the evaporator using less power. On a sunny day these units will operate 30%-50% more efficiently. Basically, when you need AC the most, they work the best. Some units can also operate for heating in the winter. Emptor caveat as all solar hybrid AC units are not created equal. Models using DC inverters for the compressor and fan will be more efficient. Units using heat pipe evacuated tubes will be more efficient than thermosiphon evacuated tubes. By law, all air conditioners are required to have a SEER (Seasonal Energy Efficiency Rating) of 13 minimum. The Energy Star label may be used for units that are SEER 14 or higher. Unfortunately, many solar hybrid AC units do not have a SEER rating. Do not be fooled by terms such as "calculated SEER," "EER" or "aBTUs." Taking a conventional AC unit and adding after market evacuated tubes to the unit voids the SEER rating as the unit was not tested that way. Buy only units that have been tested for SEER with the evacuated tubes installed by the factory. Also be cautious about claims indicating a tax credit. I am not aware of any tax credits for solar hybrid AC.