in this link u will find details on thermal performance of evacuated tube solar collector. and u can refer SUKHATME text book for more details related to analysis of solar water heater.
There are two different evacuated tube solar water heaters, one normal one where water passes through a metal tube coated with black paint from outside and tube is replaced inside a glass tube. The space between the metal tube and glass is evacuated. Then simple energy balance can be used for analysis from basics of first law of thermodynamics and heat transfer.
The second type, it uses the concept of heat pipe. In this case the working fluid passes through a pipe with on end of the heat pipes are mounted. The analysis more involved.
A number of books are available from McGraw Hill and other reputed publishing companies. You can refer the books by Kreith, Sukhatme for the thermal analysis of evacuated tube. As Prof. Abdulmajeed has stated, you may have to decide on the type of evacuated tubes you wish to work. The analysis differ with the type of evacuated type.
It is still difficult to obtain experimental data on any type of evacuated tube in the literature with the inclusion of the parameters involved in the analysis.