Hot Water

Serving the Colorado Four Corners region of Durango, Cortez, Dolores, Silverton, Pagosa Springs and the Farmington, New Mexico region.

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“You pay for a solar hot water system whether you buy one or not.”–Tom Lane (2004), author of Solar Hot Water Systems, Lessons Learned 1977 to Today


Solar energy has two basic applications: 1) photovoltaics to produce electricity, and 2) solar thermal or heating. The latter is primarily about heating water and sometimes applications to heat air. This page is concerned with water heating of what we call dhw (domestic hot water) or sdhw (solar domestic hot water). This is the water that is used for the dishwasher, food preparation, laundry, showers, and baths. How much of this hot water can a solar thermal installation in southwest Colorado realistically supply? Easily 80% over a year’s time and up to 100% in the summer. That would make solar the primary source of heat with electricity, natural gas, or propane as the secondary backup.

How reliable, efficient, and maintenance free are solar thermal systems?

Let’s put it this way: they are not the systems of your father or grandfather. From 1977 to 1986 the solar thermal industry enjoyed a 40% tax credit. Many large corporations introduced systems that didn’t work for long–they had design flaws, were too complex or too expensive. A few were effective and are still working today. However much has changed since the solar boom years that ended in 1986 when, seemingly, the energy crisis of the 70’s was forgotten and oil was again king and cheap. No more worries. Till now. There is a growing appreciation that fossil fuels are not infinite or cheap to access; and while coal, the direct competitor with most solar applications, is in abundant supply for now, there is a growing concern for its true cost in pollutants and CO2 emissions. In short, no more boom and bust for solar and now that the solar thermal industry is in its second generation, it has grown slowly and steadily in a sensible manner without all the quality problems that went with the aforementioned boom period. Today’s solar thermal technology has come a long ways and is truly reliable, effective, and low to no maintenance.

So, what does a solar domestic hot water system cost?

Here are some facts about cost to consider:

  • The Dept. of Energy says that electricity costs grew 24% in Colorado over the four years before the recession. This is about 5% inflation per year compounded.
  • LPEA says a sdhw system will cost somewhere in the range of $7000 to $12,000. $9500 is a good median number.
  • There is a federal solar water heating tax credit of 30% of the system cost and you can roll it over from one tax year to the next until you use it up.
  • The magazine Journal of Appraisal says that for every dollar saved annually in energy bills with a solar system, $20 should be added to the value of the home. If, for example, you save $500 per year in utility costs, then at a multiple of $20 your home is worth $10,000 more.
  • Your ROI will be 6 to 7%. This is better than most investment vehicles and you have made a meaningful contribution to the health of planet earth, a matter of unquantifiable value.

What about commercial applications?

The tax credit is 30% and the MACR accelerated tax depreciation method can be utilized over 5 years so that the sum of the two could realistically be the equivalent of a 50% savings off the initial cost of the solar system. If you own a car wash, laundromat, restaurant, hotel, motel, or institution you probably use a lot of hot water. Since these types of businesses usually have access to cheap natural gas it might seem at first like solar heating would not be cost effective, but due to economies of scale and the fact that the heating demands are often in real time (less hot water storage required) solar heating can be a good deal even as a replacement for natural gas.

What about tankless water heaters?

These are growing in popularity and it seems that just about everybody asks about them as an alternative. Tom Lane, author of Solar Hot Water Systems says: “Tankless water heaters do save space, but not much energy. Numerous tests by independent third parties, have shown only 10% savings versus conventional electric water heaters and 15% to 20% savings versus energy efficient conventional gas water heaters over a 24 hour period. Most manufacturers of these expensive water heater systems exaggerate the savings. Daily savings quotes of 25% or higher versus modern electric or gas water heaters are simply not true. In 2004, hot water manufacturers were required to add additional insulation to all water heaters, making instantaneous water heater savings more insignificant. Tankless water heaters have serious problems with scaling in hard water areas.” So when the true percentage savings of the instantaneous tankless heaters is compared to the 80% for solar, then solar is usually the obvious choice. But if you can’t do solar for whatever reason or need to save space and don’t have hard water, then a tankless heater might be right for you. A tankless heater could also be the backup for solar.

So there you have it, and the quote at the top of this page makes perfect sense. If we don’t buy a solar hot water system, we have as good as paid for one with never ending utility bills and the money that could have gone to our pocketbook is given to the utility company instead. So if you think a solar hot water system will work for you, please give us a call or use the contact page to email us and we will be happy to set up an appointment for a solar site analysis to see what kind of installation is possible.

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