Stationary Heat exchanger for solar tracker???? Greeting, I am working on a solar tracker and I considering a stationary heat exchanger to aid in ease of fabrication and to keep cost at a minimum. I am planning to add a small reflector dish and a magnifying lens to relocate the focal point behind the main parabolic reflector. This would allow for the heat exchanger to be stationary. The shape of the heat exchanger would resemble the appearance of a reversed capital J, that would allow the focal point to always be focus on the heat exchanger as the tracker followed the sun through out the day. What is the best material to use for the heat exchanger fabrication that can be easily obtained. This is my first attempt at a solar tracker. Thanks in advance for any help received.