I have contacted kaltech for solar water heater and they made something called site inspection three times, which made me bit doubtful about the company.
My plan was to install 150 liters as we have three bathrooms and kitchen. They said 210ltrs and finally we installed 210. 8 months running, so far never faced any problem. The company says that the maximum temperature is 80 degrees. But I feel its more than that .
I believe the company gives proper support also as they have called two three times to check if all okay; based on my experience, I would recommend this product.