Sri Lanka
Description of technology
Solar still is an apparatus where brackish water is distilled utilizing Solar Energy. For a tropical country like Sri Lanka which is blessed with more than 270 good sunny days, solar distillation of water is an appropriate technology. The efficiency of the Solar Still is further increased when it is used in dry zone of the country.

Construction :
1. Use of blackened corrugated metal sheets increases the heat absorption capacity.
2. Either concrete panels or metal sheets can be used for the cover box, of which the upper surface is a transparent glass. The glass is glued on to the cover box.
3. Underneath the corrugated tray there is a layer of insulation of coir fibre.
4. Brackish water inlet and the distilled water outlet ( PVC sockets) are placed as shown in the picture.

Operation :
1. The solar insulation makes the internal temperature to rise due to the phenomena knows as “green house effect”
2. The hotter dry crests transfer the heat to the water troughs. The water is heated by this method as well as direct solar energy.
3. Water which condenses on the under surface of the glass trickles down along it and falls on to the channel at the lower end.
4. The water which gets collected into the channel is withdrawn at an outlet.
Specific Features
It replaces the use of chemical and mechanical methods of water distillation/ purification.

This unit is capable of producing 5-6 bottles of distilled water on an ordinary sunny day. When used in the dry zone the yield will be more.
Keywords (maximum 5)
Solar, distillation, corrugated
Status of Technology
Fully Commercialized
1) Uses solar energy, which is readily available and free of charge. Hence no operational cost involved
2) Portable
3) Safe and Simple Operation
4) Easy Construction
Areas of application/Business opportunities
Areas with saline water.
List of components used
Part List
1. Solar still body
2. Tray
3. Glass cover
4. Stand
5. Gutter
6. Water intake port
7. Distilled water outlet port
Name of the component
Total area required (sqM)
3’ x 4’ ft = 12sqft
Materials required for construction
No. Description Unit Qty 1 3mm thick plain glass Sqm 1.08 2 Aluminium sheet G-22 Sqm 2.88 3 25 mmx25mmx0.7mm Aluminium angle m 2.7 4 25mmx 25mm 1mm Aluminium box m 4.6 5 25mmx 25mm 3mm Angle iron Length 1 6 Regiform sheet 25 mm thick.
USD 60
Procedure of Installation
Still body is manufactured with Aluminium sheets and Aluminium angles using pop rivets for joining. Glass aperture is fixed on to the Aluminium body using a flexible sealant and the gutter, fabricated with stainless steel is fixed inside the box to collec
Maintenance requirements
Except for the incidental damages to the glass aperture, there will be no major maintenance. Occasional painting of the corrugated sheet may be necessary.
Labor cost
USD 40
Other costs
USD 70
Total investment
USD 170
Name of the organization
National Engineering Research and Development Centre,
Address/Zip code
IDB Industrial Estate,
Sri Lanka
0094 -11-2236307, 0094-11-2236384