solar hot water - worth the cost in W. Washington?

bahansenAugust 6, 2008

Has anyone from Western Washington put in a solar (thermal) system for heating hot water? Was it cost-effective?

I've done some research on this but still have questions about our specific situation.

We had planned on having a propane-fired hot water heater for the home we are building, but our builder suggested we consider a solar system with an electric water heater as a backup instead. It would cost an additional $4,700.

We have 3 kids, ages 2, 5 and 8. The home is on 4 acres. We are a family that likes to get dirty, however I am pretty careful about keeping showers short, running the dishwasher only when full, and washing with cold water when I can.

The home is two-story and the roof has a nice, unobstructed southern exposure, which is where we would site the solar panels. The home is already roofed with a lifetime roof.

My husband, who is a CPA and former loan officer, said by the time we pay interest on the $4,700 and the system depreciates, it doesn't make sense to do this, especially since we have a lot of cloudy weather in winter. He wonders if this is a fad.

We will be using propane for cooking and to fire our backup furnace, but our primary heat will come from a wood stove.

Thank you in advance for any feedback!

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I lived in the Seattle area for many years, and have solar water heating now (but no longer in Seattle). From my recollection of the climate, a solar heater would do well most of the year.

If your family uses 80 gallons of water a day, and propane costs $2.30 a gallon (as it does here), then your cost for water heating with a 65% efficient gas water heater will be about:

(80 gal)(8.3lb/gal)(120F - 60F)(1 BTU/lb-F) = 40000 BTU/day

Or, 40,000/0.65 = 62000 BTU into the water heater,
This is 62000/92000 = 0.67 gallons of propane a day.

At $2.30 per gallon, this is $560 per year.

A well designed solar water heating system should save about 75% of that, or about $420 a year.
A pretty good return on a $4700 investment, and the return is tax free and fuel price inflation protected. In our area, propane has gone from $0.86 per gallon in 2000 to $2.30 per gallon this year. The system also adds value to the house. There may be some rebates available as well.


    Bookmark   August 7, 2008 at 12:33AM
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Thank you so much, Gary. That is exactly the information I was looking for. The only other thing I am curious about is maintenance on these types of systems - is it much more time-consuming or expensive than a standard system? I'm wondering if the panels need frequent cleaning, etc.

Thanks again for those calculations. They helped us a great deal!

    Bookmark   August 7, 2008 at 5:33PM
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you should look into an evacuated tube system.

    Bookmark   August 9, 2008 at 12:15AM
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The good solar water heating systems are low maintenance.

The collectors have around a 30 year life. I suppose its a good idea to clean them off once in a while, but I don't think that most people bother.

There are usually one or two pumps -- these are reliable,and used a lot in heating system (e.g. radiant floors) -- life is around 20 years.

There is also a controller, which should also last a good long time.

If the system is a closed loop system that uses antifreeze for freeze protection, the antifreeze should be checked for acidity every year or two. It should be replaced if it becomes acid. The check for acidity is very simple, and you could do it easily. Replacing is the antifreeze is not difficult, but can be hired done if you prefer. Just as a guess I'd say this might be an every 5 year kind of thing.


    Bookmark   August 9, 2008 at 7:01PM
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hey are you in Washington DC or Maryland & need your AC/heating system repaired or installed? just visit or call 301.219.3000 & satisfy your needs

Here is a link that might be useful: Washington DC & Maryland AC repair

    Bookmark   June 22, 2013 at 6:13AM
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