Mark built his own solar hot water system.  Here's how he did it.

As Submitted from Mark:

I made the panel years ago.  The panel backing is corrugated metal roofing.  I placed 1/2 copper pipes in each valley, a total of 10 pipes.  This year I remade the box for it.  The box is made of 2x4s and the double insulated glass comes from a used French door.  The box is approximately 5' by 3'. 

I insulated the box with blue foam and painted the entire collector flat black.  The panel is connected directly to my hot water heater in a loop.  The connection starts at the bottom of the tank, then through a solar water pump, and next to the collector.  From the collector, the water travels back to the top of the tank to the connection for the cold water.  The pump is powered by a 10 watts solar PV panel.  I also purchased a solar powered differential temperature sensor.  It will turn on the pump when the temperature to the water coming out of the panel is hotter than the water in the middle of the tank.  I tested the panel in July before installing it.  I laid it in the sun for 45 minutes, and it heated the water to 190 degrees!  I then connected it, and it heats my 30 gallons of water 130 degrees on a typical sunny day.

If you have any questions for Mark, email him at mmergist@bellsouth.net.
Check out his website for more up-to-date installs: mmergist.esmartguy.com