> What does the device do?
The solar thermal water disinfection system treats water in the way that it boils it using the sun’s energy. In the morning, or the evening before, you fill the device with water and in the evening there are, depending on the sunlight’s intensity, up to 50l treated water available. This makes it an alternative to boiling water on a stove.
> What differentiates the device from boiling water on a stove?
The device uses solar radiation as it’s sole energy source. Thus it is independent from the grid, wood or coal. This is better for the environment, as no greenhouse gases are released and there is no deforestation. But the user also profits directly. There is no smoke, which can lead to health problems and you can save time and money, because you don’t have to oversee the boiling and don’t have to spend money on firewood or coal. Additional benefits can arise from alternative use cases (eg. pre-heating water).
> What can’t the device do?
The device can’t remove chemical contamination (eg. fluoride, heavy metals). Muddy water can clog the device. In this case the water should be filtered first.
> What do I have to consider regarding the water source?
The water should not be chemically contaminated. Additionally there should be no turbidity or mud visible. To achieve this a filter prior to the device could be helpful. The water should be free of sewage or organic material. The water hardness should be low.
> What do I do if the solar radiation is insufficient?
The device should be able to work at least between a latitude of 40° north and a latitude of 40° south. If there is permanently no water coming from the device, it could be a problem with the construction. The fault could be insufficient insulation.
If the solar radiation is not enough (eg. clouds) other methods should be used to treat the water.
> What do I have to consider in daily use?
Parts of the device can get quite hot. Be especially careful at the output tube of the device, as hot steam can be emitted here. If the device is placed in direct sunlight it should not “run dry”, that means there should always be water in the tubing. To stop the device, the absorber has to be covered. If the device should not run for a longer period of time all water should be removed.
> How much does the device cost?
The cost for the construction can vary a lot so it is not possible to state an exact price. The aim was to achieve material costs lower than 100€ to 200€. The construction can be done using the construction manual. Using the device does not expose any extra costs. In the long term single components might need to be replaced.
> Which tools are necessary for the construction?
We restricted us to the use of common tools. More on this can be found in the Project data sheet or the construction manual.