From my experience I used T*sol (http://www.valentin-software.com/en/products/solar-thermal/14/tsol) for an annual dynamic simulation of a solar thermal system.

Another solution could be TRNSYS (http://www.trnsys.com/), which is a more general transient simulation tool, where you can also perform solar thermal simulations.

Thanks Noussan. I will seeT*sol. I had experience with TRNSYS 14 years ago. must be a much advanced version available now.

You can also consider freely available software:

- RETscreen that has a simple module for SWH systems from monthly global titled irradiations and air temperature

- System (or Solar) Advisor Model (SAM) from NREL from TMY meteorological hourly dataset with internal computation based on TRNSYS, if I make no mistake.

http://www.retscreen.net/ang/g_solarw.php

http://sam.nrel.gov/

Dear Taib,

Adding on Philippe´s answer recommending RETScreen for SWH projects, please find an example of one paper that my former master students (EMN-France) and I wrote on the feasibility of using SWH in an apartment building located in Cape Town, South Africa.

https://www.researchgate.net/publication/277311554_Technical_and_economical_prefeasibility_study_of_a_solar_water_heating_%28SWH%29_system_in_an_apartment_building_in_Cape_Town

I hope it gives you an idea of how this software works and, of course, how brilliant students may benefit from using RETScreen (free tool developed and sponsored by Natural Resources, Canada).

Best regards,

Luis 

Conference Paper Technical and economical prefeasibility study of a solar wat...