All solar thermal systems need electric pumps to operate, except thermosiphon and ICS setups. However, you can't just plug the pump in and leave it running all the time. If you did, it would reverse the energy gathering process, dispersing stored heat through cold solar collectors into the night. The installation needs a control system to switch the pump on when there is heat to be gathered and off when there isn't.
In many cases, mounting the heat exchanger is one of the easiest parts of system installation, especially if you buy a pre-packaged kit; you just put the module on the storage tank and tighten a few unions. However, you may decide to construct your own heat exchanger from individual parts. In any case, the first step is to install the storage tank, then attach the exchanger.
There are many different sensors that work with solar thermal control systems, ranging from flat models which bolt onto equipment, to screw-in threaded models, to pointed models designed for immersion in liquids. Most consist of a ¼-inch diameter copper cylinder about an inch long, with two wires sticking out the end.
Good plumbing is a return on investment in itself. Proper plumbing, carefully planned and implemented with professional soldering and workmanship can last 100 years, so it's worth doing it right. If you're a newbie, you will want to either practice beforehand or employ a skilled professional.
The main advantage of using DC power to run a solar thermal installation is that you can draw that power from a PV panel and, at the same time, eliminate the need for a controller.
Since PV-based power will only switch on when the sun shines, the solar thermal installation's pump will only run when there is heat to be gathered. When the sun disappears, both the PV power and the pump will switch off.
Before you start any serious plumbing work, make sure you have the right tools. Your system schematic (you did create one, didn't you?) will tell you how much piping you need, as well as all the fittings and other consumables required.
You will also need:
Like any expensive equipment containing lots of metal and liquid, a solar thermal collector array needs to be grounded. Collectors can act like huge static electricity absorbers, gathering charge from nearby lightning strikes and passing it along all the copper pipes to the controller (in an AC system). One big power surge and your controller goes pop!
There is a definite art to plumbing with copper pipes. Thankfully it's fairly quick to learn, though your first few cuts and joins are likely to produce amateur results. If you've never installed copper pipes before, buy some extra parts and practice!
Like most questions in the solar thermal arena, the choice of an AC or DC system is subjective, depending on your needs and your system type. Let's start with the unavoidable limitations:
If you're new to plumbing, you will want to practice soldering pipes before you try your skills on an actual solar thermal installation. It's not difficult but it's extremely important to do the job well or you'll get leaks and other problems. Practice makes perfect!
