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The Sal Still Water Distillation Panel

Low cost, low maintenance rural water purification.

The Sal Still is the only mass produced passive solar distiller in the market. The practice of distillation to purify water is centuries old, and many versions are custom fabricated all over the world. PASSIVE solar distillation is a UNIVERSAL technique to provide safe drinking water to the underdeveloped rural areas of the world. It purifies water regardless of the source. It can purify dirty polluted water from creeks, streams, ponds, wells as well as “desalinate” brackish groundwater and seawater. This simple technique requires no electricity or expensive filter changes. The challenge in deploying this natural, ZERO CARBON FOOTPRINT process on a large scale has been the low production rate per given size. This has been due to the lack of appropriate materials and efficient thermodynamic design. Though many passive solar distillers are available, they are made from rudimentary design concepts and do not optimize the use of the available solar energy, do not have economy of scale and do not use advanced materials for high thermodynamic efficiencies. 

The patent pending Sal Still by Voltek Water and World Environmental Solutions has been designed to overcome the shortcomings of existing designs to provide a sustainable water purification solution for the rural communities of the world. Sal Still produces 400% or more distilled water than other conventional solar stills in the market. The highly efficient thermodynamic design and use of nanotechnology enhanced materials maximizes use and recycle of heat once collected from the sun.

  1. The central piece of the unit is the nanofiber enhanced HGWC (Heat Generating Water Channel). This double walled channel is made from a plastic that has been infused with graphitic nanofibers. The presence of graphitic material in the plastic enhances its ability to convert light to heat, as well as increase the thermal conductivity of the walls to transfer the generated heat to the water contained within the double channel.

  2. The top and bottom layers are similar to a double paned window. The material is optical quality plastic which allows >93% of the light to pass through and hit the HGWC. There is an air pocket which acts as insulation and prevents the heat from the HGWC top and bottom layers to escape via radiation into the atmosphere.

  3. Low quality waste heat, such as that available from diesel exhaust generator sets, can be used to triple the production capacity to 60 LPD.

There are no moving parts in the entire system. The team of Voltek Water with MTI and WES bring the latest in Nanofiber Technology to this development of solar water distillation. The MTI and WES groups are proud to be associated with Voltek Water and we keenly offer the Sal Still passive solar distiller for cleaning water where there is available unsafe water.

Sal Still passive solar distiller

 Shown above is a bundle of 5 panels producing 100 litres of clean drinking water per day. The water is fed by gravity from the reservoir tank behind the panels. This polluted feed water is pumped 200 meters from a creek to the tank reservoir.

Each Sal Still panel has the ability to distil approximately 20 litres of water per day, in Tropical and Sub tropical geographical locations. Large capacities can be obtained by simply bundling the modular panels together. 2,500 Sal Still units can be deployed per hectare, producing 50,000 litres per day of distilled water.



Additional Videos

Video Animation:
Water Scarcity:
Documentary Video:

  1. Installation: Sal Still can be provided with an optional aluminium insert within the frame to allow higher strength anchoring for cyclone prone areas. These stills also have a rain catchment channel.
  2. Flow: Sal Still systems typically operate without any pumps, on head pressure generated by as little as ½ meter. Solar powered pumps can be integrated as part of projects to facilitate groundwater extraction, transport, etc.
  3. Filtration: Sal Stills can be back flushed by simply reversing the flow periodically. They are configured with wide channels, and therefore a reasonable amount of suspended solids can be tolerated. However, excessive turbidity in the water will cause frequent back flushing requirements, and should be addressed with suitable measures such as allowing the water to settle, and locating the intake at a higher level of the feed tank, etc.
  4. Salt Build-up: The process of evaporation takes place on a multi-layered plate (see video). The flow rate over each stage is such that the salts should still stay in solution and be discharged with the concentrate. However, there will be salt build-up on this multi-layer plate. This plate is “removable” and can simply be rinsed when the salt layer builds up. The system will function fine even if there is a slight build-up of salts, so aggressive maintenance is not required. We recommend removing and rinsing the plate once a month if the feedwater is seawater.
  5. Other:The top surface of the device is treated with a coating to minimize dust collection, but common sense maintenance such as cleaning the surface so sunlight is not blocked. 

………………..Clean water from polluted water.

For areas where there is no water source available, we proudly offer our proven MultiGen “Air to Water” systems, which can produce water from the humidity in the atmosphere, while providing Cool air suitable for Air Conditioning. This allows our group to supply water in many varying conditions around the world, whether there is water that’s polluted, or making water where there is no water.

………………..Water where there is no water.