Solar Water Heating P

The Renewable Energy site for Do-It-Yourselfers

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 systemthat 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.

DrainbackandClosed Loopsolar water heaters

Making and evaluating collector fins

Reflectors to Improve Collector Performance Heater

Other Applications(Agricultural, commercial,…)

Solar water heating system components(heat exchangers, tanks, pumps, …)

Protecting pumps etc. from freezing…

MaintenanceandTroubleshootingfor solar water heating systems

Information onpumps,heat exchangers,heat storage tanksControllers, 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 theExperimentalsection as well.

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.

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.

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.

FSEC Solar Thermal Resources Pages (very good):

FSECs 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.

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

How to get articles from Home Power …

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.

How to get articles from Home Power …

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

How to get articles from Home Power …

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,

How to get articles from Home Power …

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.

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.

Build and Integral Passive Solar Water Heater

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.

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.

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.

Our collector performance calculator …

Empirical Investigations of Solar Water Heating Technology

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 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

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.

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.

W.S. Gus Baker, Tome Wykes, Oregon State University Extension, 1986

This is from theOregon State University Extension…

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

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

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

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

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.

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….

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

Build Your Own Solar Batch Water Heater

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 thisbook.

Simple DIY bucket at a time solar batch water heater

A 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.

Construction Manual in English …(pdf)

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.

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.

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

This is Peters 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.

Details on Philips 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.

A very detailedconstruction manualis provided.

This 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

How to get articles from Home Power …

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.

Dougs Thermosyphon Solar Water Heater …

A description of Doug Kalmers homemade thermosyphon solar water heater.

A very simple and inexpensive setup.

All the details on this fascinating solar project…

This 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

An interesting thermosyphon solar water heater from New Zealand. Built in the 60s, 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.

Review of Thermalstar Technologies Thermosyhphon Water Heater,

HomePower Magazine, October 2003, Ian Woofenden

A 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.

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.

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.

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.

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 theSupplierssection for some potential sources.

Davidsdrainback 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.

Davids website has a number ofinteresting projects…

This is a really excellent blog style article on installing a solar water heating system that uses the Butler Solar Wand heat exchanger.

How to get articles from Home Power …

Home Power magazine article, issue 88

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.

with some salvaged parts. Good detail.

Maine Solar Primer Closed Loop Water Heater

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

Ibelievea lot of commercial SDHW applications can makemore financial sense thanresidential applications with the increased economies of scale. I have adoptedcommercial solar DHW as a hobby, and would be happy to helpanyone with questions.

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

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

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

All the construction and performance details…

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.

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

How to get articles from Home Power …

Butler website — good installation and design info:

Describes a solar water heating system that uses only one conventional water tank. Theinnovative heat exchangerfits 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

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,

Finding Mother Earth News articles…

Mother Earth News Article, Issue 93 May/June 1985

John Canivans 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.

Kevin 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.

The next 5 Entriesare 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.

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.

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.

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

Extensive build, testing, and performance information is provided…

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.Testingindicates 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.

The 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.

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…

Scotts YouTube video on his CPVC collector…

This is a collector design that Scott Davis came up with that uses half inch CPVC pipe

backed 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.

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….

Ive received feedback from a number of people who have built or are building the system described above or variations on it — Ive 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.

Full details on design, construction, and performance…

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 latitu