We chose to install a drainback system, which allows for excellent freeze protection during the winter and has features that keep it from overheating.  The gist of the system is that when the sun is out, a sensor gets warm and turns a pump on that circulates a water/anti-freeze mixture through the collectors.  As the fluid travels through the collectors, it picks up the heat from the sun and warms the water in your tank.  When the sun stops shining or your tank water gets hot enough, the pump turns off and the water drains from the collectors and back into a reservoir.  This draining process is where the drainback system gets its name and is the foundation of its operation.  There is no fluid in the collectors to freeze or turn to steam.  A very simple and elegant system; however, installation can be more complicated than other designs.

We began our journey into this system with the installation of the collectors on the roof.  Each of our four collectors are 4’x8’x4” and weigh about 150 lbs each.  I wanted to get the collectors mounted on the roof during the fall so I could make all the roof penetrations before the snow came and made working on the metal roof hazardous.  One afternoon, eight friends and a keg of beer (after the raising of course) made the panels go up like clockwork.  We had several people on each roof level of the house and just handed the panels up.  Before the raising, I had affixed mounting hardware to the roof the panels would be anchored to.  As the panels went up, they needed to be plumbed together; an interesting and comical process.  I roped up and hung head first down the roof and was sweating copper pipe as best I could.   At the end of the day, the connections were made and beer was had by all…

At this point, I had to bring copper pipe down through the roof and into a utility closet on the top floor of the house.  Doing this in a house that has eked out every imaginable storage space is difficult to keep the pipes hidden.  There was much finagling and tricky sweating to be done, but in the end it was complete and a tidy installation.  The closet that holds the SDHW system is about a small as you could make it; plumbing was tight and difficult to access.  I would recommend sizing the area larger than you think, especially if you ever have to service the system. I’m skinny, and I barely fit into the closet to work on the system.

Our system has two storage tanks (one in the SDHW closet and the other in the basement).  The upper tank is strictly for storing heat and doesn’t contain potable water.  We use a series of heat exchangers to transfer the heat from the upper tank to the tank in the basement.  The system is more complex than most since we have a masonry heater that heats the water as well.  Most homes can have a system that consists of one tank.  Our upper tank is a 104-gallon tank from Europe that weighs 412 lbs when empty.  My friend Bill and I hauled the tank upstairs using a 20:1 haul system and creative lifting techniques.  In the end, the tank was in place and no one was hurt.  The weight of the tank must be taken into consideration when placing them upstairs.  Our tank weighs 1,362 lbs when full of water.  The structure of your ceiling must be able to support this significant load.
Next month, I’ll continue on through the system and detail my final plumbing connections and start with the operation and tweaking of the system.

Mike hopes others install solar hot water systems while the federal tax credit lasts.  He can be reached at This email address is being protected from spam bots, you need Javascript enabled to view it