Last Sunday my friend Mauricio and I extended the plumbing for the loop that will cycle distilled water through the panels.  We also mounted a piece of 3/4" ply to the framing I built to mount the Steca TR0301U controller.  I realized today that perhaps I should have used some kind of dialectric union between the iron pump flange and the copper pipe to avoid galvanic corrosion.  Luckily this is easy to add at this point as I haven't sweated anything into the pipe beneath the pump.

 That got me online researching what kinds of dialectric unions to purchase.  I read many opinions on DIY and plumbing forums that suggested that water temperatures over 160 F can quickly degrade your typical galvanized steel-to-rubber-to-brass union.  The hot water loop through the panels should be able to easily achieve those temperatures, so I'm left wondering what to do.  So many questions!  I have a email in with Solartrope to get resolution on this.

Next to do is hooking up the galvanized steel pipe to the cold and hot water ports on the SunEarth tank.  Again, dielectric unions will be required to transition to copper and I have the same issue of running very hot water through the unions.  My understanding is that the water in the solar storage tank will very often be scalding and that it's the mixing valve that ultimately modulates the water temperature.  

The panels are still lying on the roof awaiting my purchasing Geocel roof sealant and the right kind of membrane roofing.  It's slowly coming together...