Something From Nothing - DIY Solar Heater From Scrap Bottles




Introduction: Something From Nothing - DIY Solar Heater From Scrap Bottles

One day, while walking I stumbled upon illegal dumping ground in the outskirts of the village - a familiar scene in Bulgaria: green meadows, blue sky and... piles of garbage dumped by fellow villagers. "One's trash is another's treasure", I said to myself and started collecting empty plastic bottles. This is to be my experimental environmentally friendly solar heater.

Step 1: Here's My Treasure

About 100 empty bottles are required. The more - the better.

Step 2: This Is the Wood Drill Bit

This is the wood drill bit I used to drill the bottles. You can buy it from any hardware store. This particular one is 18mm.

Step 3: Drilling the Holes

I drill a hole at the bottom of the bottle and in the cap

Step 4: Passing the Hose

For heating the water I used old garden hose. The bottles are strung together like this.

The bottle creates a greenhouse effect - the heat from the sun is trapped inside the bottle and is warming up the water that runs through the hose.

Step 5: The Pump

For circulating the water I used a 12V DC Hot Water Brushless Circulation Pump. Got it from Ebay for about $14 with free shipping. It consumes just half an amper, so it can be connected to a 10W solar panel and make the solar heater self-running.

Step 6: The Heater

Here's the finished heater. An old barrel was used to keep the water. The pump circulates the water from the bottom, through the black hose to the top of the barrel.

On a sunny day it makes hot water. It would be more efficient, I presume, if the barrel is insulated to keep the heat in.



    • Creative Misuse Contest

      Creative Misuse Contest
    • Tiny Home Contest

      Tiny Home Contest
    • Water Contest

      Water Contest

    98 Discussions

    Glad you could use up the rubbish. Wish people had more care for our environment.
    I think from looking on here, painting the bottles black would increase efficiency. :-)

    3 replies

    Yes, painting anything flat black will cause it to absorb more heat. This is why most new cars come in shiny colors like white or silver.

    I was about to suggest in order to increase efficiency white / transparent bottles should be used ....with a black hose inside.....

    Makes sense. Then there would be less losses to the air because of cooling. Basically the bottles are acting as insulation. Think it would work even better if matt black hose was inside a vacuum but the bottles would just collapse if you tried to make a vacuum in them.

    Recycling empty plastic bottles as you have is absolutely amazing. What many of us don't know is it takes about 1 cup of oil to make 1 plastic bottle, especially the clear water bottles. And it takes many lifetimes for a plastic bottle to disintegrate. Thanks for your Instructable and putting trash to good use. Last note, quit buying bottled water. Nothing wrong with drinking water from the tap and help save more resources.

    Styrofoam could insulate the barrel. If you find some, dumpsters can have them also.

    Looks like it will work! The black hose will heat up by itself but never thought of using bottles to keep heat in. I am going to have to try this since I am off the grid and a Redneck Hillbilly forever! Always looking for ways to make things work better.

    2 replies

    Lucky and blessed!!! It isn't easy but it is definitely worth it! I wouldn't change it for a million dollars. (Wish I had a million dollars tho'! :) )

    Check my new utilisation of plastic bottles ;-)


    I have also seen some excellent plans online (probably even here) that use plastic bottles to build a greenhouse. A wooden wall frame is constructed and filled in by stacking plastic bottles on their sides (or vertically depending on the bottle size). A 2 x 2 x 2m greenhouse will use up to 1,000 bottles. And it actually makes a good looking and efficient structure. Here are some examples:

    Another thing to consider when playing in passive solar heating is this. You can make a box, use asphalt shingle material as a backer, and lay in thin walled copper tubing. Put any window glass over the front, so the sun's energy gets magnified, and run water through the system using a small pump. We built one of these years ago, to heat a huge swimming pool, and it was an awesome project with great returns on investment. The trick is to make the sun warm it up, and air tight the whole thing, so it keeps the warmth.

    That is really awesome. I love it when people think differently. Very inventive. Congratulations.

    Not sure if this is old news but here in North Central FL country folk fill gal milk jugs with water and put them around orange trees and other plants when we have a deep freeze period ... it can get down to 17 for several nites, but during day it will be in 50's during cold winters. Anyway I put about 8 of them in my small greenhouse and it seemed to have worked to keep fm freeze. Theory is that as water goes into freeze mode it gives off heat? Could this be true? I put some other jugs around delicate plants outside and it seemed to have helped. Unsightly though. I saved all the jugs in 2 huge trash bags for next season. I swear it saved my peach tree which is an early bloomer and then I lose all my blossoms to a late freeze.

    6 replies

    Good info still ooohlaa. I was thinking painting "flat" black since that is the best absorber of heat from my experience. Technically, flat black is the best absorber of light in the specific wavelength range that transfers to heat.

    Like Gordyh noted, heat tries to obtain thermal equilibrium (balance). Therefore, to clarify, there is no such thing as energy known as "hot" or "cold." "Hot" or "cold" is a range of sensory perception based on our internal environment touch sensory inputs of our nervous system based on our created/evolved standard temperature and pressure environment in relation to an input of more or less heat than the body temperature or heat unit since our living being can only survive between a certain range of temperature without aid of external environment devices.

    Basically, hot goes to cold to balance the heat. Some materials have heat capacities that absorb more heat than others, as well as thermal conductivities that transfer the heat at different rates. Water absorbs more heat than air due to its heat capacity being more and transfers the heat slower due to its thermal conductivity being less.

    OK, tmi... anyhow... I went on a tangent and wanted to note that I grew up using flat black spray painted milk jugs for the most part throughout the outside garden and green house. We'd make hoop houses with clear or black plastic depending on what we were growing and place the milk jugs in those also for the outside garden. Sometimes, we'd just leave the jugs out next to tomatoes though I don't recall using outside of plastic too much.

    We'd also cut the bottoms of some of the milk jugs and use the milk jugs as "mini" greenhouses. Some were flat black and some were left opaque.

    Just like to add to your excellent notes, the sensory perception is often dependent on the speed of transfer. That's why when and water and air or metal of the same temperature is touched our reaction can be quite different. The water is very efficiency transfer medium (makes good molecular contact) so we "feel" the water as colder as the energy loss is much faster. Our body interprets the speed of energy transfer as a bigger heat differential (the bigger the difference the faster the transfer). Where with drier air, the air acts as an insulator, so the immediate point of contact warms quickly to equilibrium, so it doesn't feel as cold. To make the air feel like water we have to make the air move around more, so that thin layer touching the skin gets moved away.

    Right temp1, I have to look at the units... though I want to say what you are referring to is the materials property of "thermal effusivity."

    the water to ice and vice versa is known as "phase change", and like any system of change it requires and/or releases energy. It actually takes/releases quite a lot of energy to make it happen, so what happens is the water continues to lose energy to the air until it can't do it any more, then the packing shape of the water starts to shift into something more convenient at a low temperature, like people huddling together in the cold. When enough of the water molecules have achieved that state, if a little more energy is _added_, the whole lot starts to compact together in the new "ice" form. As each molecule slips into it's new more efficient form, it releases a gasp of energy, triggering the molecules next to it, until all the molecules are locked into the new "ice" pattern. If you do the cooling -real- slow, and be very very careful not to bump the water, it can get well down into the negative Celcius temperatures...and a slight tap and the whole thing starts to turn to ice instantly in front of your eyes! Amazing to watch.

    Some ice packs use similar processes. the chemical reaction sucks in energy, but the new chemical from the reaction is might also suck more energy in depending on it's melting point!

    If you throw a bit of sand in those water containers, you should find they hold their heat a little longer

    Yes, Ice at 32 degrees has less energy than water at 32 degrees. Also in the act of cooling water has to give up heat.

    Perhaps more effective is a water misting system. Mist the trees with water and before the trees can freeze the water has to be evaporated. Trees can't freeze with any significant water on them.