What if you could build a DIY Solar Water Heater for only a mere $30? You can, thanks to a Brazilian eco-designer who has tried it out first. About 70% of home electricity costs are spent on heating water. Solar panels can be extremely costly. The up-front cost can be high, although long-term savings can be huge. But there is another low-cost way to reduce energy costs. It is called a passive solar water heater, which requires only PET bottles, PVC pipe and an aluminum sheet. According to the designer, it is low cost and a safe, easy project for the home that you can do yourself.
The working theory behind this project is simple. The aluminum sheet focuses the solar power utilizing concentrated solar power – CSP – which is using certain materials to focus sunlight onto a small area in order to take full advantage of or maximize the solar thermal energy effects while the plastic bottles consume solar beams and help hold the temperature. The PVC pipe helps form the loop to keep the water in constant circulation. Thermosiphon (or thermosyphon) is the term on which this project is founded and refers to a method of passive heat exchange. Essentially, fluid is circulated without the need for a mechanical pump through convective movement. The liquid moves as it is heated because it expands and becomes less dense and more buoyant than colder liquid, which is denser and circulates to the bottom of the loop. It is a cyclic flow. All of this is caused by solar power which radiates light and heat.
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An even simpler theory when building this project is the more warm water required, the larger the project needs to be. So more bottles, more pipe, and other materials will be needed. Of course, it may cost more than $30 in supplies, but the cost-benefit outweighs the expense. This DIY solar water heater project has become popular all over the internet and world with people implementing it into their homes and even schools. The State of Panama in Brazil created a Do It Yourself downloadable PDF manual that many people have used to build their own solar water heating devices. The metal pipes go through the bottles creating what's known as a greenhouse effect that heats the pipes with the suns energy thus heating the water you can then use for your baths and showers.
All you need to make this DIY solar water heating system is 60 2 Litre plastic bottles, 50 cartons, 70 cm of PVC pipe, 11.7 m of PVC pipe, 4 90-degree 20 mm PVC elbows, 20 20mm PVC T-connectors, 2 20 mm PVC end caps, PVC glue, black matt paint and roller, sandpaper, self-amalgamating tape, rubber hammer, saw, and wood. You'll use the 100mm PVC pipe as a mould and then cut off the bottom of the plastic bottles. Then cut the 20mm PVC pipes into 10 by 1m and 20 by 8.5 cm pieces, and put them together with the T-connectors. You can then cut and paint the cartons and the one-meter long pipes and assemble them together. The panels have to be at least 30 cm below the tank on a south facing wall or roof to capture optimal sunlight. Also the plastic bottles should be switched out about every 5 years because they get cloudy which reduces the amount of sunlight able to get through.