How to Build a Solar Water Heater

Learn how to build a solar water heater for your home.

| September 27, 2013

The Homeowner’s Energy Handbook, (Storey Publishing, 2013) provides practical advice and working plans for reducing or eliminating your dependence on fossil fuels. In this excerpted chapter, author Paul Scheckel details how to build a Solar Hot Water Batch Heater and offers tips to keep it running at peak efficiency. Buy this book from the MOTHER EARTH NEWS store: The Homeowner’s Energy Handbook. 

Solar Water Heating in Your Home

This is a very simple design for a batchtype solar water heater that uses a thermosiphon loop to move water between a solar thermal collector and a storage barrel. While it’s not the most efficient method for solar water heating and works rather slowly, it effectively demonstrates the operation of a thermosiphon and its connection to hot water storage. Better yet, the system can provide useful amounts of hot water for an outdoor shower, washing garden produce, keeping a biogas generator warm, or any number of other uses you can think of. Because it uses water, the system must be drained when the weather turns cold.

Buying all new parts for this solar water heating system might cost around $300 or $400, but there are many ways to modify the design to incorporate salvaged parts or for enhancing the system. For longevity and durability, the parts should be rated for UV exposure and high temperatures. Most plastic (PVC and polyethylene) will start to deform above 140°F, and typical garden hose will not hold its shape much over 100°F.

The parts list includes recommended materials and temperature ratings. Use materials that can withstand temperatures up to 180°F, such as metal, CPVC, or polypropylene fittings, as well as high-temperature water hose material, such as EPDM rubber. Black-colored hose will assist in absorbing solar heat. If you can’t find what you need at your local hardware store, plumbing supplier, or home center, shop online through industrial supply companies (such as Grainger or McMaster-Carr).


Four 8-foot 2x4s
Five 8-foot 1x4s
2 1/2" deck screws
3/4" roofing screws or galvanized sheet metal screws
Two 2 x 8-foot corrugated metal roofing panels
High-temperature, flat black spray paint
One 100-foot, black EPDM rubber garden hose, 3/4"
I.D. (inner diameter), rated for 200°F
One hundred 8" black plastic cable ties, UV-resistant, heat-stabilized, rated for over 200°F
One 55-gallon barrel, black plastic, preferably with wide-mouth top
Two 3/4" NPT (National Pipe Thread) /GHT (garden hose thread) brass faucets, rated for 180°F
Teflon tape
Two 3/4" polypropylene bulkhead fittings, rated for180°F
Two 3/4" brass garden hose-to-tubing adapters
Two hose clamps
One 36" length foam pipe insulation

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