Increasing efficiency with solar water heating

You probably know by now that photo voltaic solar panels have been part of my master plan for this home since day one. Utilities are expensive, especially electricity. My wife and I are usually pretty good about turning the lights off when we leave a room, but the bills can still add up.

My goal in doing this project is to keep energy costs down and minimize my carbon footprint while maximizing indoor comfort. There’s a complimentary technology available that I’ve been considering installing on the roof adjacent to the one where our 42 PV panels will be installed.

Solar thermal panels are a bit more expensive than PV panels, and there are a few differences. PV panels use the sun’s energy to generate electricity, while solar thermal panels use solar energy to generate heat. The heat generated by a solar thermal panel can be used to heat water or other fluids and can power solar cooling systems. That means, when I turn on my hot water, the system would be pre-fed with solar-heated water. This type of system would reduce the amount of electricity needed to heat hot water, which would further drive down my utility bill and carbon footprint.

Solar thermal systems are great because they don’t require any fuel and they’re predictable. Under optimal conditions, solar thermal panels can generate power 24 hours a day - you can probably see why I am excited at the thought of installing such a system onto the roof of my new home.



As with all systems though, there’s more than one type of solar thermal panel and some intricacies that I have to get through before I make a final decision. For this two-part episode, we will be joined by Rod Hyatt of HTP Comfort Solutions - he’s been working in the field for many years and should be able to give me some insights into what type of system to install and what the material requirements will be.

In part two, I’ll make my final decision about whether or not to include this system. Stay tuned!


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  • Hi Barnabas, thanks for your comment! Part two of our solar thermal super feature includes an in-depth conversation that covers many of the subjects you are interested in learning about – Rod and I take a look at the components we’ll be installing and go through some of the particulars of the system I chose. I think you’ll enjoy it!

    As for propane alternatives, I didn’t factor it into the equation because I am trying to minimize my use of fossil fuel sources for this project. My goal is to be as eco-friendly as possible in selecting and building systems for my new home, so that we can save money and enjoy optimal indoor comfort!
  • Hopefully, Part 2 will include some factual documentation – utility rates, system costs, construction hurdles, geographic location. Also, if you intend to mention thermal system cooling, please differentiate these system performance characteristics from thermal heating; these are totally different animals with vastly differing financial performance metrics. If the article length of Part 2 is no longer in length than Part 1, I doubt this topic could reasonably be covered. And, as Mark K. has pointed out, 24/7 power not going to happen, at least not any time soon without an investment in either significant battery storage – hot water tanks are certainly thermal storage – or an envelope design with exceptionally high thermal resistance.

    Some other points: (1) The argument completely negates water heating sources other than electric. You should include propane alternatives to the decision model. (2) the contractor references a “drain-back” design vs, a glycol solution. If this it to be considered you should weight the freezing risks and carefully evaluate the drain-back controls and redundancy; (3) any such evaluation should also consider instantaneous electric water heaters.
  • Hi Marc, Thanks for your comment. My home won’t be totally “off-grid”, but we’ll definitely try to use our renewable energy systems as much as possible. If you have any tips for us, we’d love to hear them!
  • Not sure how your Solar Thermal will generate power 24 hours a day. Solar Thermal production is dependent on sunlight,