I have been using Kaltech Energy solar water heater since July 2011. 150 ltr capacity, temperature generally above 70 degrees, I was bit worried that may not work during rainy season, but it works. So far it worked very efficiently, I have called the customer service when found a leak from the tube top. Two technicians came after an hour or so, they were very keen to know the problem. They explained why the leak was, tightened the tube. They called two three times later to check the leakage, very good customer service.
Generally very satisfied, would recommend.