Getting into hot water—Solar water heating pays for itself five times over

[OKIsItJustMe]

http://www.eurekalert.org/pub_releases/2009-03/ip-gih030909.php

Public release date: 9-Mar-2009

Contact: Vivek Khambalkar
[e-mail]
Inderscience Publishers

Getting into hot water

Solar water heating pays for itself five times over

An analysis of the engineering and economics for a solar water-heating system shows it to have a payback period of just two years, according to researchers in India. They report, in the International Journal of Global Energy Issues, on the success of the 1000-liter system operating at a university hostel.

The current focus in the developed world is on advanced technological approaches to alternative energy sources, such as photovoltaic cells for solar power and harnessing wind and wave with elaborate systems to generate electricity. However, the cost of such systems may be prohibitive for some applications in the developing world. They also often ignore the fact that a mundane process such as heating water might best be carried out using direct heat from the sun rather than including a waste energy-conversion step.

Vivek Khambalkar, Sharashchandra Gadge, and Dhiraj S. Karale at the Dr Panjabrao Deshmukh Agricultural University, in Maharashtra, India, explain how they have evaluated the various costs and benefits involved in solar hot-water production. They have compared solar hot-water production per liter with electrical energy approaches and found that solar heating is 57 percent of the internal rate of return.

"Solar energy is the only renewable energy source that has wide range of uses with commercial viability. Solar energy provide water heating, air heating and electricity through various modes of applications. The use of solar energy for thermal purposes is the most cost-effective way of utilizing the resource. A solar water heating system satisfies the need of warm water," the researchers explain.

Importantly, the payback time for the initial investment in equipment and installation is just two years. This compares very well to a photovoltaic system used for electricity generation if it were only being used to heat water. Photovoltaics have a payback period of several at least a decade and sometimes double that.

The solar hot water system used in the study is installed at the Jijau hostel, part of the Dr Panjabrao Deshmukh Agricultural University campus, in Akola, Maharashtra state, India. The team estimates that the system will effectively pay for itself five times over, given an estimated working life of about twenty years.

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"Solar water cost and feasibility of solar water heating system" in Int. J. Global Energy Issues, 2009, 31, 208-218

[Pab Sungenis]

1. How much do these systems run, usually?

How much of an investment would the average home owner need to plunk down to switch to solar water heating?

As with anything else in American culture and new technology, the important matter is price point.

[leveymg]

4. About $5000 before tax credit

Solar pool and domestic hot water heating, grid-tie and off-grid ...The typical cost of a residential solar hot water heating system is $4500 to $6000 before tax credits and they can reduce your water heating energy costs by ...
http://www.sunpowerofaz.com/wst_page4.html

[Captain Hilts]

7. Wow. But folks use these throughout the 3rd world. Why so expensive here? nt

[Massacure]

18. Copper is not inexpensive.

Copper is a good thermal conductor, so it is often for the pipes that hold the working fluid in the solar collector.

Some collectors are also vacuum sealed too. Vacuums act as good insulators and don't prohibit light from passing through. Making something air tight requires a fair amount of precision though.

[One_Life_To_Give]

8. Depends upon performance level expected

If you expect the Hot Water Tap to give you 120F +/- 3F will be much more expensive than one that gives "warm" water.

Customer expectations vary greatly around the world. The industrialized world has a much higher expectation of performance and with that comes conciderable price and complexity. A typical household shower may be warmed purely by sunlight across much of the globe. But in the developed world the Solar Input may be nothing more than a pre-heater for the fossil fueled system.

[Pab Sungenis]

9. True, but even then

it's an energy savings. It takes less electricity or gas to heat water from 80 degrees to 120 degrees than it does from 40 degrees.

[One_Life_To_Give]

13. Still it's a Niche Market

Outside of heating pool water, this tech is only being used by Environmentalists. Generally adds no value to a potential home sale.

I don't know what all the maintenance headaches are concerning leaks, finding someone to service the rest of the HVAC system in which this is tied, etc. But it appears that for many people in the US the savings is not worth the hassel.

[AZCat]

25. HVAC system?

I thought we were talking about water heaters for domestic hot water, not water heaters for hot water coils in air handlers.

[OKIsItJustMe]

26. Hot water is hot water

You can do either.

My pseudo-in-laws had a "boiler" in the basement that provided hot water for heating and for bathing/washing. An existing system like that can be hybridized with a solar water heater.

[AZCat]

28. Not really.

Heating hot water generally is treated to prevent rust/corrosion and bacteria, because it's a closed loop. It isn't potable. You can use it to heat domestic water, but you have to use a heat exchanger - no mixing.

Sadly, the only contact I have with solar water heaters these days is removing them. The Southern Arizona VA Hospital here had a large array that had been dormant for years - they just demo'd it a few years ago.

[OKIsItJustMe]

30. Exactly (they had a heat exchanger)

I didn't mean to say that the same water was used in both systems.

[AZCat]

31. Then yes, it works fine.

The same thing applies to geothermal systems, which should have similar payback periods (depends on size of installation and useage).

[One_Life_To_Give]

27. A Hot Water system for most of the world is "Roughing It"

for most westerners. Billions would be happy to shower with clean water, and it being Optionally over 50F is a real plus. But people in the US have come to expect 120F on demand, any time, in not so insignificant quantities. Not so easily done with solar and for simplicity done by using fossil fuels to make up the difference to a consistent, warm enough temperature.

[AZCat]

29. Are you sure you meant to respond to me? n/t

[leveymg]

10. A basic system can be an old oil drum painted black and a garden hose.

It's set you back about $30. If you already have a well and a pump, it's almost free.

[Sal Minella]

14. Black garden hose laid back and forth, back and forth, on roof with southern exposure

also worked in one environmentally-friendly house we stayed in -- they had auxiliary water heater for rainy/cloudy days but it wasn't used much.

Edit to add: Water came from a spring higher on the hill, so plumbing was
gravity feed.

[NickB79]

17. I've seen a system like that, only with a glass sheet over it to act as a greenhouse

And the owners claimed it worked very well. They said their first attempt was to run the hose through hundreds of empty plastic bottles, which also worked but looked a little too ugly for their tastes.

[Dont_Bogart_the_Pretzel]

19. Question... did the water taste like rubber?

I've got hot water problems at home and bought 20 ft 3/4 black rubber hose at Lowes and was gonna snake it around a door way and down a short walkway from the water heater to the kitchen sink(under the cabinet). Anyhow, I was about to start the project and my S.O. smelled it and said no. He doesn't like his water tasting like rubber. I guess I'll go with PVC... measure... cut... elbow... repeat, repeat,....

[OKIsItJustMe]

20. First, there are different types of hose

Some hoses are intended for drinking water, most are not.

Second: what you really want is a heat exchanger, to isolate your drinking water, from the water that's flowing through the hose. Something like this:
http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12850

[Dont_Bogart_the_Pretzel]

21. Thanks for the info...

good read.

[OKIsItJustMe]

23. You're welcome

Decades ago, I spent a Summer working for a pool company. I saw several ways people took advantage of solar heat to heat their swimming pools (including coils of hose on the pool deck.)

[Nihil]

22. Question: Why are you drinking your hot water?

As long as you don't use the rubber hose for your cold water supply
then what's the issue about taste?
:shrug:

[Dont_Bogart_the_Pretzel]

24. I don't want my rice to taste like rubber,

or will it?

[leveymg]

2. Take the money out of the banks and buy

things people need and will provide sustainable green employment and energy-independence. I'd like to see the remainder of the TARP put into production and installation of residential solar, photocells and wind turbines, along with immediate production of plug-in hybrids.

[Captain Hilts]

3. I've never understood why we don't do this here. It's done througout the world. nt

[leveymg]

5. Same reason people commute in 7,000 pound SUVs

Tax structure and piggy GOP culture encouraged petroleum consumption while it tried its best to ignore green alternatives.

[Captain Hilts]

6. What kind are used in this country? nt

[leveymg]

11. Ford, Chevy, Dodge, Hummer . . .

Duh . . . ????

[OKIsItJustMe]

12. EERE Conumer's Guide: Solar Water Heaters

http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12850

[pscot]

15. India is a warm, sunny place

Results here in cool, rainy 16-hours-of-winter-darkness Seattle might be a tad less positive.

[OKIsItJustMe]

16. You might be surprised—Even with (Seattle's) clouds, solar water heaters are a viable option

http://seattletimes.nwsource.com/html/makeitcount/2002842178_ecoconsumer05.html

EcoConsumer

Even with our clouds, solar water heaters are a viable option

By Tom Watson
Special to The Seattle Times

Think of it as your revenge on those endless gloomy Northwest winter days.

You can put the sun to work for you, to help the environment and reduce your energy bill. It's no joke — Washington state has become a hotbed for solar energy. And the best way to start is to jump into hot water.

For the average Western Washington homeowner, a solar water-heating system has the fastest payback of any solar technology. By greatly reducing the costs of water heating, a solar hot-water system can pay for itself in eight years, says Larry Owens, president of the nonprofit Shoreline Solar Project.

It may not be Southern California, but our climate works surprisingly well for solar. Findsolar.com gives Western Washington a "good" rating for the sun available for home solar-energy projects.

…