Solar Water Heating

Solar water heating systems have a good economic payoff, and are manageable systems to install or build as a DIY project.  Some of the solar water heating designs are very simple and low cost.  You can save as much as $7000 by building your own system.  There are just over one hundred projects with full construction details listed below -- all free. 


The projects range from simple batch heaters for warm climates through closed loop and drain back systems that will work in any climate.

One of the systems is our own $1,000 solar water heating system that has provided a solar fraction in excess of  90% through our cold Montana winter.


My thanks to the people who have built systems, and then taken the time to send in pictures and descriptions for others to use.


Directory for this page:

Information on pumps, heat exchangers, heat storage tanks Controllers, pipe insulation, backdraft dampers and other components for solar space heating systems here...

Solar Water Heater kits or packages...


If ya wanna be a solar pioneer, take a look at the Experimental section as well.


Report Broken Links ...


Hands-on Basics
The Home Power and FSEC articles listed below are the best way I have found to get up to speed with building a solar hot water heater.  They are very well done, and very hands-on.
Solar Site Survey ...


Before you embark on any of the solar projects listed below, you MUST do a solar site survey.
This will ensure that you actually get enough sun on your collector to make it worthwhile.
It only takes an hour, its fun, its easy and you will learn something about how the sun moves.      Solar Site Survey...
Solar Hot Water: A Primer,
Ken Olson for the Arizona Solar Center


This is a basic introduction to solar water heating, and provides a description of different types of systems and their pros and cons.  A good place to start.

See the entries below for more details on each type of system, and for systems you can build yourself.
If the number of types of systems Ken describes seems a bit overwhelming, then concentrate on 1) batch systems, 2) drain back systems, 3) closed loop systems, and 4) thermosyphon systems -- these are the most common and robust.
Some additional considerations if you want to build your own system...
Solar Thermal Resources
Florida Solar Education Center

FSEC Solar Thermal Resources Pages (very good):

FSEC's main page on solar water heating...

Good detailed section on system installation including collector mounting, plumbing, tank, ...

The Solar Thermal Manual provides a good description of the various types of solar water heating systems, as well detailed sections on installation and troubleshooting -- lots of detailed how-to.  Very useful.

Also, good Installation Pictorials for the entire solar water heating installation.

A Solar Hot Water Primer
Ken Olson

This article is currently available as a free download from the Arizona Solar Center here

How to get articles from Home Power ...
Search for Issue 84
Overview of Solar Water Heating
Home Power magazine article, issue 84

A very good overview of the types of solar domestic hot water heating system that are available. Pro and cons of each. Some system sizing and installation information.

 This is similar to the article above, but with somewhat more detail in some areas.

SDHW Installation Basics -- Part 3: Drainback System
Chuck Marken and Ken Olson

How to get articles from Home Power ...
Search for Issue 97

Drainback Systems
Home Power magazine article, issue 97

Very Good description of the ins and outs of the drainback style solar hot water heating system.  Good hands-on detail.

Solar Hot Water for Cold Climates,  Parts I and II
Ken Olsen and Tom Lane

How to get articles from Home Power ...

Closed Loop Systems
Home Power magazine articles, issues 85 and 86

Very good articles on selecting the components for a closed loop solar hot water heating system (suitable for cold climates). Lots on installation detail.  Covers closed loop antifreeze systems and drainback systems.

Installation Basics for Solar Domestic Water Heating Systems,
Chuck Marken and Ken Olsen


How to get articles from Home Power ...
Search for Issues 94 and 95

Installing Systems
Home Power magazine article, issue 94 and 95

Good two part article on how to install the components of a closed loop solar domestic water heating system.  Lots of construction detail -- no prior knowledge assumed.  Very good explanation on how to put together and install a closed loop solar hot water system. Very detailed.

Pump and Plumbing Sizing for Solar Water or Space Heating System

Details on solar pump/pipe sizing...

This page covers the details of sizing the pump and the plumbing for a solar space or water heating system so that the system efficiently transfers heat from the collector to the storage tank without being excessively large.

Details on solar pump/pipe sizing...

Build and Integral Passive Solar Water Heater

David Bainbridge

Finding Mother Earth News articles...


Mother Earth News Article, Issue 85 Jan/Feb 1984

A primer on building passive solar water heaters that integrate collection and storage in one package – sometimes called batch heaters.  A good overview, and just enough detail to be useful.

David is also the author of "The Integral Passive Solar Water Heater Book", which is good, but hard to find -- Thanks to David, its a free download below.

Solar Water Heating Calculator

On the Wayback Machine:



This is a good solar water heater calculator from

It calculates what you are spending on heating water as a function of water heater type, fuel type, usage, ...
And it estimates the savings for a solar heater.

The website is now gone, but the calculator is still avialable on the Wayback Machine.

Get Into Hot Water -- Home Power's 2008 Solar Thermal Collector Guide,
Check Marken with Doug Puffer

How to get articles from Home Power ...

Good review of all SRCC certified flat plate and evacuated tube collectors. 
A rundown on construction and SRCC performance is provided for each collector.
Good discussion on flat plate vs evacuated tube features and efficiency.

Other related info:
SRCC ratings info ...
Our collector performance calculator ...
Suppliers ...
B2E Expansion Tank Calculator


A calculator you can used to size the expansion tank on your solar water heating system.

Empirical Investigations of Solar Water Heating Technology

Dennis Scanlin

How to get articles from Home Power ...

Home Power Magazine article, issue 58

Appalachian State University does side by side comparisons of several types of solar water heating systems.  Good comparison data for several types of systems.

Batch Water Heaters
Batch solar water heating systems are very simple.  Easy to build and easy to maintain.  Good Do-It-Yourself projects.  These systems must be drained during the winter in cold climates to prevent freezing.
The Integral Passive Solar Water Heater Book, David Bainbridge

Download this book

This book is out of print, and difficult to get, but David Bainbridge has agreed to make it a free download.


This is a really fine book on all aspects of designing and building a wide variety of solar batch water heaters.

The book has a great mix of how-to and engineering design information -- great for builders and experimenters.

Thanks to David, the full content of the book is available here as a free download.

By Example Batch Water Heater



This is a pretty detailed story on the building process for a homemade batch hot water heater. 
I think one of the most valuable things is it passes on some things NOT to do -- things they tried that failed.

Here are some more things NOT to do on a batch heater.

Batch Solar Water Heater Plans and Data,
W.S. "Gus" Baker, Tome Wykes, Oregon State University Extension, 1986


This is from the Oregon State University Extension...
Lots of good material there.

Detailed plans and performance data for a simple Do-It-Yourself batch solar water heater.

Thanks very much to the folks at the Oregon State University Extension for making this 1986 Extension publication available -- a note about this doc...

Rodale Batch Water Heater

Very good write up and plans for a batch water heater.  This one even looks nice.  Good how-to detail.


Florida Batch Water Heater
Rovert Owens

How to get articles from Home Power ..


Home Power magazine article, issue 93

Good description of installing a commercial solar batch water heating system.  Good detail on installation process and experiences with the batch heater.

Maine Solar Primer Batch Water Heater

Maine Solar Primer

A simple homemade solar batch water heater design suitable for summer use in a cold climate, or year round use in a warm climate.

Courtesy of the Maine Solar Energy Association.

Batch Water Heater Using Stock Tank as Enclosure


New updates October 09

This is a nice simple batch water heater design from Ron that uses a galvanized stock tank as the outer enclosure.

It also includes a movable reflector that increases solar gain without increasing heat losses.
Getting the Tank for a Batch Heater and Preparing It ...



It can be difficult to find a good tank for a batch heater -- here are some ways to find one, and to prepare it for use....



Simple Solar Water Heater for Developing Countries
A. Jagadeesh

How to get articles from Home Power ...

Home Power Magazine article, issue 76

Description of a very simple non-pressurized batch water heater intended for developing countries. Might be good for a cabin application. 

Construction and Installation of a batch-type homemade solar water heater -- An inexpensive, Durable System


Pretty much just what the title says.  Simple, cheap, durable, homemade.
Non-Pressurized $70 Batch Water Heater

Build Your Own Solar Batch Water Heater
Florida Solar Energy Center FS-36



This is a plan from the FSEC for a VERY simple batch water heater made from a 50 gallon barrel.  It cannot be pressurized.  You fill it from something like a garden hose, and use gravity feed to use the water. 
A system of similar, but lighter, construction might be mounted on the roof of a house/cabin to supply gravity feed hot water.  Similar to the "pillow" systems in this book.
Can't beat the price!

Simple DIY bucket at a time solar batch water heater


diy bucket batch solar water heaterA very simple batch water heater that heats up one 5 gallon bucket of hot water at a time.

Just place the bucket in the glazed box, point it at the sun, wait for a few hours, and then take the heated bucket of water to where its needed.


Beer Bottle Solar Water Heater,
Ma Yanjun



An unusual approach!

I guess you work with what's available.

A Solar Water Heater Made of PET Bottles

Update: ...

English Translation of Manual:
Construction Manual in English ... (pdf)
(Thanks to Chris for finding this!)


An interesting solar water heater design made from PET bottles.  It looks like plastic(?)  pipes run up the center of each row of PET bottles.  The PET bottles (I think) act as glazing, and also hold reflectors made from beverage cartons(?)

The Instructional Manual has a lot of good pictures that make it fairly clear how it goes together.  
Its an inventive design with most of the materials coming from stuff that would otherwise go to the landfill.

(Thanks to Cameron and Tom for providing more info on this.)

Thermosyphon Water Heaters
Thermosyphon use the fact that heated water becomes less dense and rises to power the water circulation through the collector.  No pump or controller is required.  The storage tank must be above collector.
A DIY Thermosyphon Water Heating System,
by Lonnie

Full details on construction...

This is a very nicely done and very simple thermosyphon solar water heating system.

The system basically consists of a collector, a tank, and connecting plumbing -- no pumps, no controllers -- very simple, not expensive, yet quite efficient.

A Simple Thermosyphon Solar Water Heater for the Tropics


All the details...

thermosyphon solar water heater for tropicsThis is Peter's nice, simple thermosyphon solar water heating system for warm climates.

All built with locally available Costa Rica materials, the CPVC collector heats water in the elevated tank, which gravity feeds to showers.

All the details...

Philip's Fiji Island DIY Thermosyphon Solar Water Heater

Details on Philip's thermosyphon solar water heater...

Philip of Fiji has built a very nice warm climate thermosyphon solar water heater.  This is a really simple system -- no pumps, no controllers, no heat exchangers, no antifreeze -- total cost $250. 
All the details...

(Could not resist showing Philip's beautiful Fiji photo)

The "lucy Caliente" Thermosyphon Solar Water Heater...

A very detailed construction manual is provided.


DIY solar water heater thermosyphonThis is a thermosyphon solar water heating system developed in Mexico that heats water in in a tank just above the collector. The heated water gravity feeds to showers etc.

There is a very detailed construction manual for the system.

The decorations are optional, but they add a lot!

How to Build and Install Your Own Thermosyphon Solar Water Heater

Perry A. Bocci

How to get articles from Home Power ...

Home Power Magazine article, issue 58

Very complete design and construction detail for building a thermosyphon solar water heater.  Includes building the collector panel, enclosure, plumbing…  Only mystery is how did he bond the copper pipes to the corrugated metal absorber?

Solahart Thermosyphon Water Heaters Website

Eco-Smart -- Installation manual and more...



Solahart is a major manufacturer of thermosyphon water heating systems.  They provide a lot of information on their site that would be helpful to a person who wants to size and build a thermosyphon system.
The 2nd site has a very detailed installation manual with a lot of helpful information on bracing roofs for the added weight and other installation issues.
Doug's Thermosyphon Solar Water Heater ...



A description of Doug Kalmer's homemade thermosyphon solar water heater.

A very simple and inexpensive setup.


See all of Doug's solar projects ...

A Large Thermosyphon Solar Water Heater System for a Hospital Laundry in Pakistan

All the details on this fascinating solar project...
thermosyphon solar water heating system in PakistanThis is a fascinating story on building a large Thermosyphon solar water heating system for a hospital laundry in Pakistan. 
Very good detail on the design and build and a great stories on the Pakistani culture and scenery.
A Solar Water Heater That Has Stood the Test of Time, Lindsey Roke

Full Details (pdf)


An interesting thermosyphon solar water heater from New Zealand.  Built in the 60's, it has a long track record of good service.
The collector has several unique and interesting features.

The article refers to SILFOSSING -- this is:
A silver-alloy solder containing 5-15% silver. It is used to weld copper to copper joints in refrigeration systems and able to withstand high pressures.  Used to braze risers to headers.

Review of Thermalstar Technologies Thermosyhphon Water Heater,
HomePower Magazine, October 2003, Ian Woofenden

thermalstar vac tube water heaterA good review of the Thermalstar Technologies thermosyphon water heater.

This is an unpressurized solar water heater. The heater uses evacuated tubes for low heat loss -- the inner tubes are filled with water that circulates to the tank via thermosyphoning -- the outer tube provides the vacuum insulation.

Opinions on freeze protection the unit provides vary, but it does provide some freeze protection via the mechanism explained in the article.

Imported Thermosyphon Solar Water Heaters

One example: ...



There appear to be a number of these imported thermosyphon water heaters with integrated storage tanks appearing for reasonable prices.  This may prove to be a good option for cost effective solar water heating.

If you have one of these, and could share your experiences, please let me know.  Gary...

Homemade Thermosyphon Solar Hot Water Heater



While this design is not going to be for everyone, it shows how simple and inexpensive a solar water heating system can be, and it incorporates some clever design ideas. 

Some thoughts on this design...

Thermosyphon Solar Water Heating System Tests,


Test of the PEX/Aluminum collector...

Test of the Copper/Aluminum collector...


Some tests to determine how well two of our homemade collectors perform in a simple thermosyphon solar water heating system -- and, just to learn a bit about thermosyphon systems.

Test of the PEX/Aluminum collector...

Test of the Copper/Aluminum collector...

One caution on thermosyphon systems is that if the potable water circulates through the collector, there can be a build up of mineral material over time.  Using larger diameter manifolds and risers should help this. 
But, if you have high mineral content water, a therermosyphon system in which the potable water circulates through the collector may not be a good long term choice.
It may be possible to clear out the deposits with one of the commercial descaling fluids.
Closed Loop and Drainback Solar Water Heaters
Drainback and closed loop systems provide freeze protection for year round operation in cold climates.  They are more complex, but within the capability of many DIYers.

Some of the articles listed below on closed loop and drainback systems are sufficiently detailed to use as plans to assemble a system from components (collectors, pumps, ...) that you purchase from suppliers.  See the information below and in the Suppliers section for some potential sources.

David's drainback solar water heating system...

This is a drainback water heating system designed and built by David. Collectors are mounted on a vertical wall and drain back to a non-pressurized heat storage tank in the crawl space. Nice tank and heat exchanger design.

David's website has a number of interesting projects...

Installing My Solar Domestic Hot Water Heating System,  Guy Marsden


This is a really excellent blog style article on installing a solar water heating system that uses the Butler "Solar Wand" heat exchanger. 
Lots of good pictures and details on the whole process.
Solar Hot Water Homebrew Style

How to get articles from Home Power ...
Home Power magazine article, issue 88

Great article on designing, building and installing a drainback solar water heating system for less than $800.  Good hands-on.

Solar Water Heating in Iowa
Roy Tonnessen

How to get articles from Home Power ...
Home Power magazine article, issue 91

Article describes an homemade closed loop, flat plate collector system for heating domestic hot water. Total system cost only $900 with some salvaged parts. Good detail.

Maine Solar Primer Closed Loop Water Heater

Maine Solar Primer, Richard Komp

Plans for a closed loop water heater suitable for year round use on cold climates.

Courtesy of the Maine Solar Energy Association

Large Drainback System for 16 Unit Appartment

Full Details...

From Alan:
" I believe a lot of commercial SDHW applications can make more financial sense than residential applications with the increased economies of scale.  I have adopted commercial solar DHW as a hobby, and would be happy to help anyone with questions."

A really nicely done large drainback domestic water heating system that serves a 16 unit apartment building in Philadelphia.

A very simple, efficient, low maintenance, and economically sound system.

Doug's Solar Water Heating system ...


A detailed description and track record of the PV pumped solar water heating system that Doug built some 17 years ago. 
Still going strong!

And, a 2nd PV powered system built for a friend.

See all of Doug's solar projects ...

Large Horizontally Oriented Water Heating Collector with a Unique Heat Storage System

All the construction and performance details...
solar space heating system This is a really nicely done water heating system from Bob and Dave.   The system uses a unique collector design in which the "risers" run horizontally instead of vertically -- for a wide, built in place collector like this, the horizontal riser arrangement saves materials and labor.
The system also has a unique heat storage vault that makes use of a bank of barrels in an insulated enclosure. 
Lots of good design, construction, and cost data...
Kris's Collector

Kris's Collector Pictures/Plans


Kris provides an extensive set of pictures of the  solar water heating collectors and heat exchangers he is making.  I doubt that most of us will ever achieve the high level of workmanship that Kris does, but there is much to learn from these picture plans.  Beautiful work.
Solar Wand -- Hot Water Assist for Cold Climates

Barry Butler

How to get articles from Home Power ...


Butler website -- good installation and design info:


Home Power magazine, issue 104

Describes a solar water heating system that uses only one conventional water tank.  The innovative heat exchanger fits through one of the water tank plumbing connections.  This system sacrifices some efficiency for a more compact system with fewer components -- this might well be a good trade depending on your situation.

The article covers another innovative Butler product that prevents solar collectors from overheating.  The Butler web site has pictures of several DIY installations, and the Documentation tab has full install and maintenance manuals for download.

One-Tank SDHW Storage With Electric Backup
Marken and Olsen

How to get articles from Home Power ...

Home Power magazine article, issue 96

Complete description of how to modify a conventional electric hot water tank so that it can be used as both a solar hot water storage tank and the backup tank.

A Homemade “Factory” Solar Collector,

Mother Earth News

Finding Mother Earth News articles...



Mother Earth News Article, Issue 93 May/June 1985

A fairly hands-on article on building a solar collector using water at the heat transfer medium.

JC Solar Homes and Solar Collectors


John   Canivan's book $30 "How to Build a Solar Hot Water System" has plans for building a solar water heating collector.  I have not reviewed these plans myself, but they are reported to produce a good product -- and, you get email help from John!

John can also be found at the Solar Heat Yahoo Discussion group.
Heat storage tanks, pumps, heat exchangers, controllers, ... Full information on heat storage tanks, pumps, heat exchangers, and controllers here...

An Experimental Trickle Down Solar Water Heating System


Lu has designed, built and tested a version of the Thomason trickle down collector with some unique features.

The system includes a unique trickle down collector, a storage tank with a new liner design, and an innovative version of a copper heat exchanger.


Handling Drain Back Plumbing with Dips
Kevin Dickson

All the details...
drain back plumbing with dipsKevin goes over a technique that can be used to allow a drain back system to be installed in cases where the plumbing cannot be installed in such a way that it all slopes toward the tank.
Be very very careful in applying this technique -- be sure to read all the rules carefully, and be sure to test the finished system for proper drainback.
All the details...
The $1K Solar Water Heating System
The next 5 Entries are for a simple, all climate, drain back solar water heating system I have been developing, and have installed at my place. 
Objectives for the system are: high performance, easy construction with simple materials, long life,  and low maintenance  -- all for a price that is about 1/7th of equivalent commercial systems.  For the first 3, quite a bit of prototyping and testing have been done to get to a design that (hopefully) achieves these objectives.
The last two are more in the experimental stage, so there would be more risk associated with using them now.

Quite a few people have built these systems with good results -- some have taken the time to send in material on their projects ...
A $1000 solar water heating

Full Details ...


As of late May 2009,  the system has been in operation for about 9 months and has performed well and reliably, achieving solar fractions over 90% over our cold Montana winter.

This is a cut at $1000, all climate, high performance, long life, low maintenance, and easy to build solar water heating system.

It combines one of the two collector designs just below with a very simple drain back scheme.  The system is unique in that it combines drain back and storage tanks into a single, large, inexpensive, non-pressurized tank.  A unique heat exchanger that is inexpensive and very efficient is used.

Extensive build, testing, and performance information is provided ...

A $5/sqft solar collector using Copper tubing and Aluminum fins

Full Details ...



This is one of the two collector types that can be used in the $1K system described above.

This is a cut at a solar water heating collector that offers a combination of high performance with a low cost per sqft, and an easy build.
See what you think!

The fin to tube thermal connection is similar to the collector above, but copper is used for the tubing instead of PEX.  This provides performance within 4% of an all copper collector in an easy to build package.

Extensive build, testing, and performance information is provided...

A $4/sqft solar collector using PEX tubing and Aluminum Fins

Full Details...


This is one of the two collector types that can be used in the $1K system described above.

There has been a lot of interest in a collector that uses PEX tubing rather than copper to convey the heat transfer fluid.  Here is a cut a collector that does this -- with careful attention to the PEX/fin joint, it can perform surprisingly well. 

This is a cut at a solar water heating collector that uses PEX tubing instead of copper to convey the heat transfer fluid.   The fins are aluminum, and a lot of effort was put into attaining a good thermal bond between the PEX and aluminum.  Testing indicates that the collector performs at 84% of and all copper commercial collector at about 1/7th the price.

Extensive build, testing, and performance information is provided...

Off The Shelf Solar DHW -- Cheap and Easy DIY Solar Water Heating

This is a more experimental design than the first three.

All the details on the prototype...


off the shelf diy solar water heater

off the shelf diy solar water heating tankThe goals of this system is to provide an easy to build and inexpensive solar water heating system that uses all off the shelf components (i.e. nothing to build yourself -- just assemble).

This is a four season drain back system.  While the parts are inexpensive, they are high quality and the life and reliability should be comparable to commercial systems.

Total cost is projected to be about $1300, and the system qualifies for federal and some state rebates.

The system is in the design and prototyping stage -- comments and suggestions are most welcome.
All the details on the prototype...

Comparing the Performance of Two DIY Solar Water Heating Collectors -- CPVC vs Copper

This is a more experimental design than the first three.

All the details on CPVC collector performance test...


Scott's YouTube video on his CPVC collector...

cpvc solar collector testThis is a collector design that Scott Davis came up with that uses half inch CPVC pipe cpvc solar collectorbacked by aluminum flashing material.   I think it is another candidate as a collector for the $1K solar water heating system.

The collector is easy to build and performs well (see test below).  There are some pluses and minus relative to durability, cost, ease of build, and designing for stagnation temperatures, but I think that in some cases and for some people this collector will be a good choice.

All the details on CPVC collector performance test...
Road Map of $1K Solar Water Heating Pages


This is a list of all of the pages on the $1K solar water heating system. 

There are some alternative designs, lots of construction detail, several tests to verify performance of key components, performance data, and several descriptions of example systems....

Working DIY examples of the $1K Solar Water Heating System
I've received feedback from a number of people who have built or are building the system described above or variations on it -- I've included some below that provide good pictures and/or writeups.

The examples listed below are from people who built a system and documented it.  The new things they have tried, and the ways in which they have adapted the system to their circumstances should be very helpful if you are building your own system.

Thanks very much to the people who have taken the time to carefully document their systems!
Kevin's WAY North Solar Water Heating System


Full details on design, construction, and performance...

NEW Performance update...

Kevin has done a really fine job on his system, and provides a very helpful write-up.  His system is in Northern BC at 55 degrees latitude, a very challenging location. 
Kevin had limited space for a tank, and worked out a copper/PEX hybrid heat exchanger design that requires less tank space, and has proven to be very efficient.

Kevin has installed a data logging system, and provides data on both system performance, and the performance of his hybrid heat exchanger.

Knick's $1K Solar Water Heating System


Full construction details here...

This is a very aesthetically pleasing $1K system installation.  The system uses large vertical collectors to give good winter performance without overheating in the summer.  The twinwall glazing also improves winter performance.
Aluminum trim work looks great and provides weather resistance.

Full construction details here...

Large DIY Solar Water Heating System in Virginia Using Commercial Collectors


All the details in a 13 page pdf...

diy solar water heating systemThis is Chris's very nice solar water heating system in VA.

It uses 80 sqft of AET commercial collectors with the rest of the system being similar to the $1K design with some nice refinements.

Unique features include using the MAXDTC programable controller, the Grundfos Alpha pump with ECM motor, a nice roof mounting system, and a fabricated single pass copper heat exchanger.

David's UK Solar Water Heating System


All the details...

DIY solar water heating system in UKThis is David's very nicely done solar water heating system in the UK.
A very nice job of design and workmanship -- many details to learn from.
The system shares the existing vented thermal store for the house to store solar heat -- a nice arrangement.

Solar Water Heating Using a Unique Master and Slave Collector Design

Full details Gordon's new solar water heating system...


Gordon's deep energy retrofit of a schoolhouse into a very low energy use home...

This is a very unique solar water heating system with several innovative features:
- It uses a Khanh Master/Slave collector to improve collector performance.
- The storage tank uses a low profile galvanized metal livestock tank.
- The heat exchanger is multiple coils of small diameter copper pipe in parallel.

Gordon also shows how a drain back system can be adapted to a difficult situation.
Full construction detials...
Rob's Solar Hot Water Project With Space Heating and Cooling

All the details on Rob's solar heating system...
solar water and space heating systemRob's solar water heating system provides domestic water heating and some space heating (and maybe cooling next summer). 
Its the first drain back system I know that uses the "hizer" (horizontal risers) design.  Heat transfer to the house is via a water to air heat exchanger in the furnace ducting.
Rob provides 42 pages of detail on design and construction.
Eric's $1K type solar system for space heating and domestic hot water
A one thousand dollar diy solar water heating systemEric provides the details on building his solar domestic water heating and space heating system.
Based on the $1K design, but with some nice refinements to meet Eric's needs.
Chad's Solar Home Heating System

Details here...


Note: this is a space heating system that uses the same collector design as the $1K solar water heating system.

Chad uses 6 4X8ft collectors mounted on his shop to heat his home, which is 200 ft away.  The collectors are based on these copper/aluminum collectors with some refinements for Chad's situation.  The collectors pivot to allow the tilt to be adjusted.
This is a closed loop system with antifreeze for freeze protection.
Details here...
Matt's $1K in Pennsylvania
copper coil heat exchangerThis is Matt's very nicely done $1K in PA.  It uses two roof mounted collectors with an about 250 gallon tank.

One unique feature is the coil of copper used for the heat exchanger rather than the usual coil of PEX. 

All the details here...
Scott's 24X8 ft Solar Space Heating Collector

Details ...


This is Scott's very unique collector.  It is built as one single unit that is 24 ft wide by 8 ft high.  The absorber is a wide version of the PEX/aluminum collector.
The ground mount and single unit construction make for an attractive and easier to build collector.  Details ...
Sandy's $1K Solar Water Heating System on Prince Edward Island

All the details...


This is a very nicely done system.  The collector design uses a unique horizontal "riserr" arrangement, and the tank includes a couple innovations, including a large PEX coil heat exchanger wound on a form for more efficient heat transfer.

Lots of good pictures and construction detail...

Apartment Version of a $1K System

Details on apartment solar water heating system...
DIY apartment solar water heaterThis is a large version of the $1K type of drain back design that solar preheats water for a 7 unit apartment building in Iowa.

Very nicely done collectors using twinwall glazing all mounted on a sturdy ground rack.  The drain back tank is inside the building just behind the collectors.
$1K in the UK

All the details on Neil's $1K solar system here...

This is a very nicely designed and built system by Neil in the UK. 
While the system is modeled after the $1K system, Neil has included a number of unique features including a fiberglass tank liner, a very nice big copper coil heat exchanger, integration with a combi boiler system, and a unique design for the collector absorber plate.

All the details here...

Ken's Large Solar Water (plus) Heating System

All the details on Ken's system...

This is a very nicely done solar water heating system that generally follows the $1K design, but includes 200 sqft of collector and a larger tank to provide excess capacity for hot tub and space heating.

Very nice workmanship, and the tank and heat exchanger show some well thought out variations that you might want to adopt.

Denver in Ohio Does a $1K System for $800!

Full details on Denver's $800 Solar Water Heating System ...

This is a very nice job on a $1K type solar water heating system with some new wrinkles including: small footprint but high capacity tank, new absorber fin former, and a cheap and efficient pump/controller combo.  With some creative scrounging, the total cost was $800.

DoItYourself Solar $1K Solar Water Heater...

Many other good projects on Nate's site including an Arduino based differential controller, solar water heater for pigs...


PEX coil heat exchangerNathan did a really nice job of building and documenting his water heating system. 
Nathan also offers details and source code for making an open source Arduino based differential controller.

The way he re-coiled the PEX coil heat exchanger is particularly interesting and should improve performance.
Woodsy's System

Full construction details and pictures...


This is Woodsy's $1K style solar water heating system.  It has some interesting design changes that might suit your circumstances.   

The system is doing well heating water for Woodsy's family.
Cory's Copper/Alum Collector

Pictures of Cory's collector ...

Some pictures of Cory's nicely constructed copper/aluminum collector.

Cory is using this for pool heating in Edmonton, Alberta.

Bill's Large Closed Loop System

All the details ...
Closed loop $1K Solar Water Heating System

This is a very interesting $1K style system with quite a few interesting design variations.  Among the unique features:

- Closed loop rather than drain back.
- Glazed with dual wall polycarbonate glazing.
- A unique collector frame that uses EPDM rubber roofing for weather protection.
- Using a custom made PVC tank liner instead of the usual folded EPDM liner.
- Lots of detail on roof mounting the collector, including the site made collector hoist shown just below.

Paul's Metal Framed "$1K" Solar Water Heater

Full description of Paul's system...

This is Paul's $1K style water heater.  Some of the unique features:  Metal collector case, Selective finish on absorber, Poly drum heat storage.
Paul also fitted the fins to the tubes with a copper based heat transfer compound.
Matt's copper HX "$1K" Solar Water Heating System

Full details here...

Matt tried a number of innovations on this system, including: copper heat exchanger, metal collector frame, glass glazing, and the worlds first bicycle powered fin grooving machine!
Some of the changes may be just what you are looking for.
Gordon's New Zeland "$1K" Solar Water Heating System

Details...  (pdf)


A nice "$1K" type system from Gordon on the South island of New Zealand.

The system features a very nice, all copper single pass heat exchanger coil, and a nice roof top, high tilt angle support for the collectors.

Details...  (pdf)

Mike's $1002 Solar Water Heating System


This is Mike's nice clean implementation of the $1K system with an adjustable tilt roof mounted collector.


A DIY Thermosyphon Water Heating System,
by Lonnie

Full details on construction...

I'm listing this system in both the Thermosyphon and $1K sections because it shows how the $1K style collector can be used for a thermosyphon system.  This simplifies the system, and eliminates the cost of pump and controller.

This is a very nicely done and very simple thermosyphon solar water heating system.

The system basically consists of a collector, a tank, and connecting plumbing -- no pumps, no controllers -- very simple, not expensive, yet quite efficient.
Making or Buying Collector Fins
How to make collector fins and evaluate collector fin designs

How to make and evaluate collector fin designs...

This article covers the various ways people have worked out for making the heat absorbing fins for collectors, fin performance, and some construction tips.

How to make and evaluate collector fin designs...

Evacuated Tube Water heater
This system uses evacuated tube collectors.  It is a closed loop system, similar to the systems described just above.
Large Drainback System for 16 Unit Appartment

Full Details...

From Alan:
" I believe a lot of commercial SDHW applications can make more financial sense than residential applications with the increased economies of scale.  I have adopted commercial solar DHW as a hobby, and would be happy to help anyone with questions."

A really nicely done large drainback domestic water heating system that serves a 16 unit apartment building in Philadelphia.

A very simple, efficient, low maintenance, and economically sound system.

Performance of Vacuum Tube and Flat Plate Collectors Concerning Domestic Hot Water Preparation and Room Heating,
Trinkl, Zorner, Alt, Stadler,
Centre of Excellence for Solar Engineering ...

A paper directly comparing the performance of evacuated tube and flat plate collectors on the same house and roof exposure.
I don't want to get into the never ending which is better battle, but this paper points out an important consideration for some evacuated tube installations.
Another live, online comparison of side by side flat plate and evacuated tube collectors... NOTE: this link may be dead - waiting for signs of life.
Compares two side by side systems with performance logging on both.

Flat-Plate & Evacuated-Tube Solar Thermal Collector,
Brian Mehalic,
Home Power Magazine, issue 132, August 2009

The article may be available here...

Or, How to get articles from Home Power ...

A recent Home Power article comparing flat plate collectors for evacuated tube collectors.

One thing that I don't think was adequately pointed out in the article is the very wide variation in SRCC tested perfomance among different models of evacuated tube collectors.
Solar Flat Plate vs Evacuated Tube Collectors
Heliodynes Opinion


This is a short paper from the Heliodyne website on flat plates vs evac tubes.  Heliodyne makes only flat plates, so one would expect some bias -- but they make some interesting points.
I'd be happy to point to similar articles from evac tube makes -- if you see any, please let me know.
Solar Water Heating Kits 
Solar Water Heating Kits  or Packages ...
solar water heating kitsThis section provides information on a number of solar water heating kits or packages that provide all the components (collectors, tanks, pumps, controllers, ...) required to install your own solar water heating system.

While this kit of parts approach does not save nearly as much money as building the whole system from scratch, it does have the advantages of 1) less work, 2) compatible parts, 3) rebates, 4) good manuals, 5) and (maybe) support. 

Solar Water Heater Kits details...
Solar Air Collector Water Heater  --  A bit unusual, but may be a good fit for some circumstances.
Solar Air Heating Systems -- Water Heating,
Steve Kornher and Andy Zaugg


Solar Water Heating With An Air Collector (1.2 MB pdf)

This is a somewhat unusual scheme for Do-It-Yourself domestic water heating with a solar air collector. 

This may work out particularly well if you are already building an air collector for winter space heating, and want to make use of its heat output in the summer, or if you just like the trouble free operation of air collectors.
This is the Water Heating chapter from the book "Solar Air Heating Systems" -- download the full book here.

Solar Hot Air Water, Steve Baer,
NMSEA Sun Bulletin, Volume 2, Number 5 1977

From the Library... This link is not working, and I am unable to locate a copy of this interesting paper -- if you have a copy or know of source, please let me know -- Gary
solar air collector to heat waterIn this 1977 paper, Steve Baer goes over three ways to heat domestic water with a solar air heating collector and measures the actual performance of each.

One of the methods uses a external copper coil wound around the hot water tank that thermosyphons water from the bottom of tank to top of tank when hot air from the solar collector is blown over it -- it was the best performer.
Reflectors to Improve Collector Performance
A section on reflector design, reflector performance, a reflector test rig, and examples of reflector use...

Reflectors offer a uniquely effective way to increase heat collected without increasing heat losses.

This section on reflectors provides: Reflector design tables, A simple earth-sun simulator you can use to test reflector designs, and many examples of effective use of reflectors.

See also the batch water heater section of this page for some more examples of reflectors used to improve collector performance.

An Easy to Build Earth-Sun Simulator for Optimizing Reflectors and Shadow Studies...

Earth sun simulator for reflector designThis is an earth-sun simulator you can build to test reflector designs or to understand sun and shade patterns on anything you can build a model of.

It allows you to see the sun and shadows for any location on the earth and any season and for any time of day. By rotating the turntable you can quickly play the sun over your model for a full day and see the sun and shade patterns. You can take readings on the model with a light meter and get a quantitative idea how much (for example) a reflector is increasing radiation.

Tracked Solar Water Heaters
A Tracking Solar Water Heating Collector

Details here...

Here is a unique solar water heating collector array that tracks the sun.  Its a nice, simple tracking and actuation system that uses readily available components. 
While the tracking makes for some plumbing challenges, the benefit is an about 30% gain in heat collected over a day.
A parabolic trough solar collector you can build

More information on the tracker:

Good Youtube Videos on the collector...


A very nice set of ganged, parabolic, tracked, concentrating collectors used to heat water. 
Can be made with common shop tools.

George now offers plans for this collector -- my thoughts on these plans...

George has also done some work on comparing tracked and untracked collectors both concentrating and flat plate..

Gray Water Heat Exchanger
Grey water heat exchangers offer a way to recover the heat energy in the hot water that goes down the drain, and use it to help heat water. 
GFX Gray Water Heat Exchanger


DOE Inventions & Innovations report:
DOE report on GFX (pdf)


A well designed gray water heat exchanger can recover a large fraction of the heat that would normally go down the drain in your shower, and some other hot water uses.

In a normal shower, you spend a lot of energy heating water from 50F or so up to 110F.  It flows out the shower nozzle, over your body, and down the drain taking 95% or so of the energy you just spent heating it.  The gray water heat exchanger uses the heat in the drain water to heat the incoming water.

Heat Recovery Units
Use waste AC heat to heat water
Heat Recovery Units -- heating domestic water with waste heat from AC

Potential Suppliers:

A calculator to estimate saving:

Installation slide show:
(this could likely be a DIY installation with help from a HVAC person to evacuate and recharge AC of refrigerant)

Florida Power Description:


These Heat Recovery Units are heat exchangers.  They pick up waste heat from your Air Conditioner just after the refrigerant is compressed and before it goes to the condenser.  This recovered heat is used to heat water in your hot water tank. 
The heat is "free", and also makes your AC run more efficiently. 
These units may may make sense for people who have long cooling seasons, and run AC a lot.  The saving depends on the size of your AC, its efficiency, how much you run it, and the length of your cooling season.   They are somewhat less effective for high SEER AC's, so make sure they will work well with your AC.

While the yearly saving in water heating costs for these units is likely to be less than a solar water heater, they are also less expensive, and potentially easier to install.
(Thanks to Gary M. for suggesting this!)
Heat Pump Water Heaters
These are small heat pumps that basically provide a more efficient electric water heater.
Heat Pump Water Heater

A couple (of many?) suppliers:

AirGenerate ...


These are small heat pumps that can be added to an electric water heater  to increase its efficiency.

They also produce some cool air as a byproduct that may be useful in the summer.

I'm not a big fan of electric water heaters because of the high CO2 cost of using power from our very dirty US grid, but if you have an electric tank, this is one way to make it more efficient.

Good Video on Installing a Heat Pump Water Heater, Tom Gocze,



This is a very good video from Tom Gocze on installing and using the Geyser Heat Pump Water Heater.

Tom goes through the fairly simple install, and also explains some other potential uses for the heat pump water heater -- very good.

Winter use of a Heat Pump Water Heater

The paper... (pdf)

One problem with heat pump water heaters is that in the winter, they dump cold air into the house.  This cold air ends up having to be heated by your space heater, and this costs energy.

This paper shows the way in which the Heat Pump Water Heater was hooked up in a Building America demonstration home to overcome this difficulty.

Heat Pump Water Heaters in Cold Climates: Pros and Cons,
Alex Wilson


Good article by Alex Wilson going over his experiences with his neat pump water heater, and looking into the problem of the heat pump water heater robbing the house of heat in the winter.
Water Heating with Compost

Several schemes for heating water with compost here...


There are several schemes that can be used to heat water for domestic or space heating use are shown at the link to the left.

These schemes generally use a pipe coil embedded in the compost heap, and collect heat that is generated by the composting process.
I'd like to hear from anyone with composting experience on how workable this all seems? Gary

Heating Water for Animals
Solar Heated and Insulated Horse Tank - Version 2

Full details - performance and construction ...


Newest version of the solar heated, well insulated, double glazed horse/stock tank.
Full construction step-by-step.

All the details ...

Solar heated stock tank in Minnesota...

solar heated stock tankKarolyn's solar stock tank has performed very well through a cold Minnesota winter.


Keeping the drinking opening from freezing


This is a great idea from Art for keeping the drinking opening in solar heated tanks from freezing during extended periods of not much sun and lots of wind.
This technique can be used on any of the tanks described here.  

Solar Heated and Insulated Stock Tank

Description and construction pictures here ...

Very nicely done insulated and solar heated stock tank. 
This design uses a galvanized stock tank as a base and builds an insulating and solar heat collecting structure over the tank.

Description and construction pictures here ...

Heated Water Trough for Livestock -- Using the Sun,
Steven Fahey,  SW Alberta

Full Construction Details...

Very nicely designed and built insulated and solar heated horse watering tank. 

Good photos, plans and construction detail. 

Steven lives in a very cold climate (even colder than mine!), so it will be interesting to see how the tank does over time.   Full Construction Details...

Super Insulated Stock Tank

All the details on how to build it....

This is Scott's really nice design for a well insulated stock tank.  Its basically a heated bucket inside of a  larger tank with the space between filled with insulation.

The energy saving for Scott has be 61%!

All the details on how to build it....

Bob's Insulated Stock Watering Tank

Full Construction Details...


This is a fully insulated stock tank with complete how to build it instructions.

The insulation should dramatically reduce, and possibly eliminate any need for a tank heater -- depending on climate.
Full details ...
Freedom's Well Insulated and Solar Heated Stock Tank


Full Construction Details ...


This is an actual implementation of the prototype described in the design in the entry just below.

A solar heated and well insulated horse watering tank.  It provides 140 gallons of water that is protected from freezing by lots of insulation and a solar collector that is built into the south wall of the tank.
Glazed with very though dual wall polycarbonate.
This tank should avoid most of the high electric bills and wasted CO2 emissions that go with electric tank heaters.      Full Construction Details...

Heating Water for Your Pig

DIY solar pig water heater...


solar water heater for pigsThis is a pretty simple water heater for a pig from the It uses an old pressure tank with some left over lumber and insulation -- costs practically nothing.

It works well, but can have problems with the watering nipple freezing.

Experimental DIY Solar Stock Watering Tank

Details to date ...


This is a first cut at a simple insulated stock watering tank that has an integrated solar collector on the south side to provide heat and prevent freezing.

The tank basically a plywood box lined with pond liner, and with a glazed sout side for solar collection.

Details to date ...
See also the entry just above for an actual version of this tank.

All-Weather Concrete Stock Tank,
Charles D. Fulhage,  University of Missouri Extension


Freeze resistant stock tank design from U of M Extension relies on earth berming and a small trickle of water in very cold weather to prevent freezing.
Idea to Reduce Exposed Water Surface On Stock Tanks



From Mark:
I’ve got a technique I have used in the past, with pretty good success, to reduce the open water exposure yet give a good drinking area for the horses. 
I cut a board to cover the top of the tank. In that board I cut a hole that is the diameter of a 32 gallon plastic trash can. The hole is cut to the size of the trash can such that the lip around the top of the can will not go through the hole. These trash cans taper from the top to the bottom of the can (I imagine so they will come out of the plastic mold). I cut the bottom off of the can. I then slide the can (minus bottom) down into the hole that I cut in the top of the lid. The lip of the can stops the can from going all the way into the tank. I then screw the can to the top of the tank so the horses don’t pull it out. Next I fill the tank with water. Now the only exposed water area I have is the diameter of the plastic trash can.  I then use the bottom of the trash can that I cut off as my floating cover. It fits in the top of the trash can pretty well because of the taper to the trash can and it limits my exposed water to only a small ring which is the diametrical difference between the top and bottom of the can. All of the horses quickly learned to just push against the trash can bottom to drink.

Thanks to Mark for sending in this idea!

Sun Tanks


Amesco and o ther commercial horse tanks...



This is a commercial product to keep water tanks for stock from freezing.

Seems like a build-it-yourself one would be pretty easy? 
Dark colored tank, insulation under and around back, Lexan for glazing, plywood housing?
Elevate it, and you could make a nice summer shower out of it?

Corbett Waterers


Uses a combination of insulation and ground heat to keep water line from freezing.

CANARM Insulated Stock Watering Tanks

CANARM Equinet Products...


CANARM horse waterers...

Several heated stock watering tanks with R15 insulation and float valves to add water.

Said to cut heating expense by 75%.

Bar-Bar-A Horse and Cattle Drinker...



Pumps water out to the waterer when the animal presses a paddle.  Water is drained from bowl to a dry well before it freezes.
Heating Water for Small Animals


This link to Pet Finders provides a list of potential solutions to keeping water dishes from freezing for cats, etc.
The electrically heated bowls they list use 45 watts intermittently -- about 15 KWH and 30 lbs of CO2 a month if on half the time -- not sure why that's their "ideal solution"  -- some of the other solutions look better to me.

If you have any other ideas, please let me know.

Passive Solar Bird Bath

Plans for a passive solar bird bath...

solar bird bath heaterThis is a nice design for a simple solar heated bird bath.

It heats the water up enough in PA winters to provide an unfrozen drinking water source for birds through the winter.

If you have ideas for improvments, add a comment here...

Three more systems from The Cattle Site



a drainback stock watering systemThe Cattle Site has several schemes for freeze resistant stock watering systems.

The systems include one that pumps water to a cup when it senses an animal, and drains it after the animal is done drinking. Another uses a very well insulated small building to insulate a large supply tank that feeds a trough that extends outside the building. And, another makes use of a large inductrial mining tire.

These two publications talk about the systems -- unfortunately, not a great deal of detail is provided

- Remote pasture watering (see the part toward the end of the article)...

- TheCattleSite article on freeze resistant schemes for cattle watering...

Other Applications 
Agricultural, commercial, industrial applications for solar water heating.
A well house using passive solar for freeze protection...

solar heated well houseThis is a very nicely done well house that is protected from freezing with a large Trombe wall.

The well thought out desgn uses a combination of the Trombe wall, concrete block thermal mass, and insulation to provide effective passive freeze protection.

Lots of good detail on the build ...

Solar Water Heating for Making Cheese


Making cheese requires lots of water heating for pasteurizing -- here is a way to do it with solar.
Large Drainback System for 16 Unit Apartment

Full Details...

From Alan:
" I believe a lot of commercial SDHW applications can make more financial sense than residential applications with the increased economies of scale.  I have adopted commercial solar DHW as a hobby, and would be happy to help anyone with questions."

A really nicely done large drainback domestic water heating system that serves a 16 unit apartment building in Philadelphia.

A very simple, efficient, low maintenance, and economically sound system.

Solar Showers  -- A fun summer project

An Outdoor Solar Shower...


an outdoor solar showerThis solar shower design uses a flat box above the shower to store and heat water for the shower. The shower is a simple gravity feed from the box.

I would guess that the relatively large collection area should make for good performance.
Nice Outdoor Shower


A really well thought out outdoor shower that uses roof collected water.
The solar heated pipe coil is gravity feed from rain collection barrels.


(I found this at: a good site on urban homesteading)

Solar Shower

Solar Shower User

This is a little write-up from a satisfied user of the solar shower.  You put it out in the sun for 3 hours, and get a 5 gallon hot shower.
And, yet another solar shower


A $10 DIY solar shower from New Zeeland


Simple summer shower in Wyoming

solar showerThis is about as simple as it gets -- the shower is a commercially available black bag of water with a shower nozzle attached.

Fill it with water, hang it on the pole for 2 or 3 hours, and its ready to shower.

Click on picture for full size
And, yet another solar shower

From PB Floyd and the Slingshot newspaper




A simple homemade solar shower made from a few lengths of 3 inch ABS plastic pipe.
Economy Solar Shower

Bob Battagin

How to get articles from Home Power ...


Home Power Magazine article, issue 43

If you are looking for simple, this is it. 


Here is an even simpler one -- the hot hose shower.

A Portable Solar Water Heater (Shower),
Raymond Meloy, Mother Earth News

Finding Mother Earth News articles...


Mother Earth News, Issue 62.  S simple homemade shower made from a car inner tube.
The Hot Hose Shower

A very simple one:
the hot hose shower.

And another one with more capacity:
Black plastic pipe shower ...

And another very nice one:

Schemes to use the hot water from a garden hose or plastic pipe coil left in the sun for a shower.
Adding an Al Fresco Shower,
Ron Cascio


These are plans for building a pretty spiffy outdoor shower.  Its not a solar shower, but I thought the detail on constructing it and dealing with drainage etc were worthwhile -- converting it to solar is left as an exercise.  Please send pictures if you do.
A Very Nice Solar Shower



This is a very nice solar shower project that was posed on the  Homesteading Today forum.

Very nicely done with its own solar batch water heater.

Collector Glazing Materials
Comparison of Solar Collector Glazing Materials...



A comparison of glass, corrugated polycarbonate, sheet polycarbonate, and other potential glazing materials for DIY solar collectors.
Protecting Pumps and Other Equipment From Freezing
Protecting pumps and other equipment from freezing... If your pump is located in an area that can go below freezing, you will need to protect the pump (and possibly other equipment and plumbing) from going below freezing.

Here are some methods....

Maintenance and Buying Used Collectors

Solar Hot Water: Troubleshooting & Repair,
Chuck Marken, Home Power Magazine, Oct-Nov 2013, issue 157


How to get articles from Home Power ...

troubleshooting solar hot water systemsVery good and detailed article on finding out why your solar hot water system is not working and fixing it.
Secondhand Solar -- Choosing A Good Used Hot Water Collector
Chuck Marken

How to get articles from Home Power ...

Home Power Magazine article, issue 112 April 06

Good article on how to select and test a used solar water heating collector.  Used collectors if in good shape, can have 20 or so years of life left in them.

Some of the high points on how to check a collector

Solar Water Heater System Maintenance and Repair

EERE site


Information on Diagnosing solar water heating system problems.
Troubleshooting Solar Water Heaters,
Florida Solar Energy Center (FSEC)

See the Troubleshooting section of this guide...


This is a  checklist to go through if you are having problems with your solar water heating system.
GoSolar Repair Guides Link not working -- checking on availability.


Some helpful troubleshooting information for solar water heating systems.
Rebuilding a 31 Year Old Suncatcher Copper tube, Aluminum Fin Collector

All the details...
rebuilding a 31 year old solar collectorDoug gives the details on his rebuild of a 31 year Suncatcher solar water heating collector.

The collector lives on to serve many more years!

Interesting Commercial Products
Velux solar water heating system that l ooks like a skylight...
roof integrated solar collectorThis is a new solar water heating system from Velux -- the people who make the popular skylights.
The installed collector looks just like a Velux skylight, and this may be much more acceptable to picky HOAs.  The collector sits flat to the roof and is flashed the same way that at skylight ism, and there are no visible plumbing connections.  Pretty nice.  The SRCC performance ratings are comparable to other good collectors.
I don't see any reason a DIY version could not be done.
The Sungrabber Unglazed Solar Water Heating System

Description and some thoughts...
Sungrabber solar water heating systemThis is an innovative solar water heating system that uses unglazed collectors with drain back for freeze protection.

It appears to offer some advantage for milder winter climates. 

Description and some thoughts...