DIY Project – Building a Solar Shower
Original article written by Francois Cramer and posted on the Pure Portugal blog, July 2018.
I am re-sharing a slightly edited version of this blog here because it is a part of our journey, and the outdoor shower is still one of our favorite summer features – so it deserves some extra visibility / love (plus some fixing up as the goats decided to snack on the bamboo screen, oops). Of course, this is a technical post in case you want to build your own such shower. A more lyrical ode to the outdoor shower may follow one day.
We live in a off-grid Tiny House in Portugal, near Guarda (in the central region, close to the Spanish boarder). We have a limited amount of solar electricity. Given that gas and other sources of energy are non-renewable resources, we decided to create a solar shower, where water is directly heated by the sun’s radiations.
I inspired myself from a mix of designs I saw while travelling and from a system used by our friends from Vinha da Manta to pre-heat the shower’s water for one of their Glamping units. The principle is relatively simple: the water circulates through a long pipe made of hard black plastic exposed to the sun and heats up. For convenience and to maximize the surface exposed, this long pipe is coiled in a spiral shape and fixed to a support. I did some research on internet to find plans to follow, but didn’t find anything convincing (especially not in French, my mothertongue) – so I inspired myself from a few videos in English and used my DIY skills and leftover materials I had at hand.
Photo: Spiral to heat the water
The water comes from one of our springs since we’re not connected to the water mains – we collect it in a water tank. At the exit point of the tank, I made a double connection: the first one can be used to connect another pipe (to water the garden for example), the second to supply the shower. Both are equipped with a valve to decide to which side the water goes.
The shower’s exit also has two connections: one for cold water, the other for hot water. The cold water line goes directly to the shower’s mixer; the hot water line goes to the spiral then to the shower. (See details further below).
There you go, we have a solar shower!
Photo: A 1m3 volume – an “IBC tank”
Let’s see in detail the different elements used, from the tank to the pipes and even the mirror and shelves I set up so the shower is not just functional but practical.
It’s a 1m3 tank in plastic, usually used for transporting different kinds of liquids. They are several types – you can buy them new but they’re easy to find them second hand. Anyway, I would suggest to choose one previously used to transport food goods (ours used to contain glucose) and not soap, oil or other petroleum based liquids. You should also make sure that it has been cleaned thoroughly or that you have enough water at hand, patience and contortionist talent (!) to clean it yourself. These cisterns are usually mounted on a base (pallet type) in wood, aluminum or plastic. With time and exposed to the elements, a wooden pallet will rot, so it seems wise to find one with a plastic or aluminum base. Sometimes, they’re made of opaque or black plastic, specially made for containing water (and thus to avoid algae to appear when exposed to sun light) – ours is in transparent plastic so we covered it with a black plastic tarp.
In English, they’re usually called « IBC tanks », in Portuguese« deposito ». Of course, you can directly connect the shower to the water mains if available to you. Our tank is + or – 15m away from the shower with probably a maximum difference in height of 2m – this creates enough pressure for the shower to run. Although, if I had to redo it, I would put the shower further from the tank (and thus lower), creating more pressure but at least, we don’t use too much water!
Connection tank – pipes
These IBC tanks usually have a threaded exit point, to fit a cap.
Watch out: don’t use a tank without a cap because the cap is used to make the connection with the pipes.
So, I made a hole in the cap to insert a piece of plumbing (in 2 parts – male and female) that connects with the other elements. Unfortunately, I don’t have a picture to show them. However, like for the other parts, I suggest you go to your local hardware shop (and not to a big store – hardware store employees know what they’re talking about and your money will contribute to the local economy in place of ending upinto a multinational’s pocket) and to get some help by explaining what you’d like to build. That’s what I always do when I have a new project.
Note: I live in Portugal and speak survival Portuguese! But I go to the shop with pre-made schematics and a few new words of vocabulary to explain my ideas and I always manage to get what I need.
As you can see here below, I made a double connection; one of them having 2 exit lines.
Photo: Double connection; one of them with two exit lines
I used black polyethylene(poly) piping, 3,2cm in diameter and 100m long – this gives 80l of capacity (a quick shower, if you turn off the water to wash, can use as little as 20l but count 40l for an average shower). The system recharges as you go and the sun does the rest – thus there is, I think, the possibility to take at least 4 showers per day. You can use a pipewider in diameter and/or a longer pipe to increase the capacity.
Spiral’s support and spiral
For the spiral’s base, I used 2 planks of wood (240cm x 6cm x 8cm) and assembled them in a cross, making 2 notches in the centre of each of them, also called a halved joint. I made the cut using a compound miter saw using this recommended guide here.
240cm is too long but that’s what I had at hand, leftover from another project. A cross 2m long, even 1,5m long would probably be big enough. If you make a smaller one, I’d be curious to know what the minimum size could be.
Photo: Two planks (240cm x 6cm x 8cm) assembled in a cross shape
Illustration: A halved joint
For the spiral, I coiled the pipe, one coil at the time, fixing each of them individually, 4 times per round and starting from the outside of the planks. To fix them, I used galvanized steel hanger strap (cut to size and sold as a roll). This step took me a few hours, alone; it would be easier to have someone giving you a hand because it’s not always easy to handle and hold in place a 100m long pipe.
Photo: Pipe coiled in a spiral shape, one coil at the time
Connection pipes – mixer
I used 2 high pressure stainless steel pipes to join the poly pipes to the shower’s mixer, in order to position them as needed (poly pipes are not very flexible). High pressure pipes are not mandatory, it just happened to be the easiest solution I found. These high pressure pipes go through a plank (the holes having the same diameter as the pipes) and connect to the mixer (it has 2 nuts at the tip of the water entry points, facilitating the connection and allowing the mixer to be secured to the plank by tightening them).
Photo: Connection of poly pipes to high-pressure pipes
Photo: Connection to the mixer, through the plank
Photo: Close-up of the tap connection
Photo: Mixer fixed on plank
As you can see on the pictures, I added a tap, on the cold water line, outside the shower, just before the mixer; this way, one can also brush its teeth, rinse something, plug a hose etc.
Mixer and shower head
Standards, bought in the hardware store. I installed a bar to be able to adjust the shower head’s height – simply screwed to another planks, itself fixed to the pallet.
Photo: Mixer, bar and shower head
Made from a pallet used to transport vegetables, opened on one side for the entrance and a bamboo screen sitting on top, held in place by 4 trunks in each corner. I cut these oak trunks on our property, they were growing in non-desired places: too close to the houses or in competition with other trees. They’re more or less 2m high and are screwed to the pallet; the screen has been tightened to the trunks using metal wire. I left a few branches (cut short) on the trunks – inside, they serve as hooks to hang soap, washing mitt etc. – outside, they serve to hang clothes, towel etc.
Photo: Veggie pallet, pallet, plank/shelf and bamboo
Photo: Trunk and bamboo screen
I tuned it a bit by adding a mirror outside, opposite to the shower, to shave, put on make-up etc. and 2 small planks to leave personal effects. Finally, I placed a regular pallet in front of it to change clothes.
Photo: Mirror and shelf
That’s it, I think I explained it all – don’t hesitate to ask me questions in comments and to send us pictures when you build your own!