Cheap Solar Heater

Introduction: Cheap Solar Heater

A video can be seen at:

Here is what you'll need:
-Plywood and some assorted pices of wood
-Copper tubes, elbows, couplings, connections, etc.
-copper or brass sheets
-Plumbers solder and paste
-A plumbers torch
-sand paper
-Used engine oil (just a little to coat the wood)
-Black paint
-Acrylic or polycarbonate transparent sheet
-plastic hoses
-plastic container
-silicon glue

Sizes depend on what you have at hand.  The longer the pipes run, the more energy they will absorb.  The wider the pipe, the less pressure losses.  JUst consider it, because copper is the most expensive item on the list.

Step 1: Solder the Pipes and Sheets

You can lay out your exchnager in a series or parallel design.  For me, I chossed the series one.  So I used 1 meter long sections of 1/2" pipes (8 pcs). plus the smaller ones, which gives a total of 9 meters of pipe.  Then I welded the copper sheets to increase absortion area.

Then run water thrugh it and test for leaks.  Rework if needed.

After the leak test, clean it with paint thinner.  And coat it with black mate paint.

Step 2: Assemble Your Box

I am probably going to get a lot of arguments against this tip, but I used burnt engine oil to coat the wood.  This keeps water and fungus off, preserving it.  Just don't over use it.  And wear gloves, I didn't!

Step 3: Cover It

So close up your SWH with your glass or plastic cover firmly. 

Chose a nice spot (your roof) and orient it to the sun's line.  (Southwards for us living in the north emisphere)  I used a simple leg support for a 30 degree angle (it is what I measured in the commercial models).

1 Person Made This Project!


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9 Discussions


6 years ago on Step 3

About the storage of the hot water...
What did you use for that tank?


Reply 6 years ago on Step 3

A plastic container with a plastic lid, size is about, erh... 40 lts, I think. I then glued polysthirene slabs and then painted those over to shield them from UV.

nice instructable, however I think it could be more efficient by adding more surface area. If you snake the copper pipe back and forth in a tighter pattern it will create for surface area and heat more water in the same amount of time. Also, if you paint only the pipe black and keep the metal backing shinny then any light would be reflected back to the other side of the pipe.


Reply 8 years ago on Introduction

ur right, but copper here is very expensive. So far, I have done few thing to it even since I built it. I have increased the isolation of the container, cleaned the polycarbon glass with brake fluid to make it clear again, tweaked the position of the box (angle). I still got hot water, even when we're at 10°C outside. And I don't any longer, own a gas water boiler since 2 years ago.

I've been asked to built more to my buddies, but I tell them they can built them themselves and they can try different dimensions. But it is a trend and everybody is getting the need to switch to solar heating.


9 years ago on Step 3

@Naveen - there is no motor. The water flows from the pressure in the line. This would go between your water supply and hot water tank. It pre-heats the water so the water tank doesn't have to work so hard. But you would still want a consistent hot water temperature, so you never want to take your regular hot water tank out of the loop.


Reply 9 years ago on Step 3

The hot water reservouir is filled by gravity it self. It is placed lower than your main tank. The water gets hot by the effect of the thermosyphon, which is itself a very slow flow, so it is very critical to eliminate leaks on the system. No pumps or moving parts are involved (except for a level float valve on the reservouir).


9 years ago on Introduction

I think the question is how do you hook this up? And what do you hook it up to? Is this a water heater? Pool heater? House heater? all of the above??

What are you using it for.


10 years ago on Step 3

hey nice work
but  how  can give connections to any motor or other for working


Reply 10 years ago on Step 3

Sorry, but I don't understand your question.  Please rephrase it.