Solar Hot Water Systems
Way back in the 70s and decades before, too, hundreds of us tried lots of ways of heating water with sunlight. Some schemes worked fine at first, but later succumbed to failures of materials and technique. Some defiantly produced only lukewarm water available only at awkward hours. Some defied the laws of physics and didn’t work at all. A few exploded. It wasn’t long before it was common to see deteriorating solar water heaters perched disconsolately on rooftops, abandoned by humiliated, exasperated owners.
Time to try again! This inspiringly-comprehensive book presents what has been learned the hard way over the past 30 years or so. Clear illustrations—many in color—show the layouts that have proved to be the best in every way. Recommended hardware is here complete with brand name and even the part numbers. Here are the most effective pipe sizes and materials and why they are chosen. Classic mistakes are attended along with their corrections. Cautions are noted; success is celebrated.
My experience in the field and 25 years at the Whole Earth Catalog tells me that every aspect has been well covered and detailed. If you follow the recommendations, your solar hot water system will be sure to work and last a long time. I consider this book as a model for collected experience on other subjects as well.
Note: a black and white version of the book is also available. I recommend the colored version.
PDF download of Chapter 2: Drainback Solar Water Heaters
PDF download of Table of Contents
Changing sunlight into electricity (PV or photovoltaic systems) captures everyone’s imagination and the publicity causes them to contact solar contractors. Once they focus on KWH’s [kilowatt hours] saved, it becomes clear that for every $20 to $30 spent on a PV system you can save the same amount [of KWH] for $1 spent on a solar hot water system.
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NEVER RUN THE INSULATION THROUGH THE FLASHING THROUGH THE ROOF DECK WITH THE PIPING. This can cause rain to run between the insulation and the piping into the home. Seal under the stand pipe before soldering around the “coolie hat.” DO NOT USE SILICONE SEALANTS.
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Favorite (15)
Katherine Hoffman
We got a solar hot water in late '07, and I LOVE it. Out electric bills went down more than I expected, and the water is HOT (unless it is cloudy for a whole day, then the electric element kicks in, and it is 120). I am in coastal Florida, and have a direct system where the water goes to the roof, no need for exchangers because no fear of freezing, so it is extra efficient. I encourage anyone in the no-freeze zone to get one of these, and anyone else to at least think about it.
gmoke
Went to the 2009 Building Energy renewables trade show last week and saw that Velux, the skylight manufacturer, is now building solar hot water systems and establishing a network of trained installers. More at http://www.veluxusa.com/products/solarWater/
The most popular solar hot water model seems to be the evacuated tube and heat pipe design, although there may be some problems with winter snow as they are so efficient that the snow doesn't melt from the evacuated tubes. At least, that's what I heard on the trade show floor.
Mike K
I'm from Israel, and we've got solar hot water in just about every single building over the whole country, and this has been the case for decades.
I wonder if there's any cross-pollination between Israeli and American expertise on the subject?
Israeli companies are used to large scale manufacturing and deployment of such systems. Would be useful to apply in the US.
jenkinsr
Australia has many variants of solar hot water systems and some federal and state initiatives offer incentives to replace old and inefficient electric heaters with solar. They work very well in our sunny latitudes, cost very little to run (depending on your booster) but are not particularly cheap to buy; for the most part they last for about 10 years and cost around $AUD3800 to replace. I think there is a disproportionate amount of profit in what is essentially a tank, a few tubes and a sheet of glass; no moving parts, just a thermo siphon...
Heat pump HW Systems from SE Asia are more cost effective at the moment, which is disappointing. .
I have yet to see a hybrid solar thermal and photovoltaic system but expect there will be one eventually.
I was not aware Israel had such a large solar industry. Linky?
Julian Cullen
There is no link to the second chapter as a free download, nor does this outfit have any intention of making it available. Bravo Sierra-
gmoke
http://www.sundrumsolar.com should get you to a hybrid PV and hot water collector.
There are also PV and hot air collectors but I don't have a link handy for them.
Kevin Kelly
@Julian Cullen: The link is there, it is just not so easy to find. I just downloaded the second chapter.