Consultation in regard to solar based water heater and water pipe design

Greetings I am considering placing central water heater for each unit in my house. Location: roof of the building which is 2 level with Annex and basement. Total 4 residential units. I want to use solar based water heater. I have 2 options Ecotherm and product from long standing national company Job requirements: Experience on solar based water heater Knowledge in routing water cycle for this kind of water heater Knowledge of downside and upside of solar based water heater Output: First output: Comparison table between both products using standard criteria for residential water heater (PDF). You should now these criteria. If you ask me. It means you do not know anything about water heater in general Second output: Revit model water cycle. You need to explain to me which cycle you are using (open or closed or independent ) with justification Time: before April 7 Budget: Not more than 65$ Report is 15$ I have ready made Revit model (check file)for the residential unit, ground water tank and septic tank and bathroom units with pipes in place. This can be shared later and the budget for pipe design is 35$ Read everything before you contact me on chat box.