1. Product Description: A solar water heater is a water heater which uses solar radiation energy for heating water. It consists basically of the flat plate collector and an insulated storage tank. The collector is a commonly blackened metal plate with attached metal tubing and is usually provided with a glass cover and a layer of insulation beneath the plate. The collector tubing is connected by a pipe to a storage tank which stores hot water produced in the collector. The storage tank can be further connected to a hot water system of a building. Solar heated water is used in residential, commercial and public buildings. Though the initial cost of solar water heater is higher than the conventional heater, its operating cost is almost nil or very much lower. The heater envisaged in this project idea is a storage tank of 160 liters capacity which can be used by households, hotels, restaurants, etc.
2. Market Potential: As hot water is a necessity for life, the means of getting this water is also a necessity. However, some goods or services, however necessary they are, are not readily available for all who want to use them, since they require the ownership of enough money to acquire and use them. All people want hot water and the means (water heaters) to heat the water. But not all can afford to have hot water through the modern heating system. Solar water heater use solar energy to heat the water; and in out country solar energy is available at least 10 months of the year. If the cost of producing and installing solar energy collecting apparatus is reduced through large scale production, solar water heaters will be needed both in urban and rural areas of the country. If only one percent of the rural families use solar water heater, the demand for these heaters will be about 130,000. If these products are introduced into the countryside and effectively promoted with appropriate financing scheme, their demand will grow every year.
3. Source of Raw Materials: The main materials needed are steel profile and steel sheet for the frame, steel sheet, steel pipes, single glazing and polyfoam insulation for the collector (absorber). All the major inputs can be obtained from local sources.
4. Process and Technology: There are two aspects of the choice of technology in solar water heater production. These are water circulation and solar collector design. Water is circulated between the collector and the storage tank in two different ways by forced circulation (i.e. by means of pump) and by natural convection from the collector towards the tank. Forced circulation has the advantage of higher energy gains and the possibility of positioning the storage tank to any place in the building. However, it has the disadvantages of higher installation costs, frequent maintenance and the necessity to be linked to an electric supply. Hence, considering these advantages, the other technology i.e. circulation by natural convection also referred as the romosylon principle is chosen for this project idea. The manufacturing process employed here mainly uses manually operated workshop equipment which is available in ordinary metal workshops. The process can be divided into four sub-processes:- manufacturing of frame, absorber plate, tubing grid, storage tank and assembly. The frame is manufactured by cutting single iron, hollow square pipe and galvanized steel and welding/faster them as per design. Cutting steel, polishing, cleaning, priming and spray painting operations are involved in the absorber plate manufacturing. The tubing grid is manufactured by cutting pipes, drilling holes and brazing. The storage tank is manufactured by cutting galvanized steel, rolling to from a cylinder and brazing/welding the joining seam and the two ends. The final stage is assembling the various parts of the solar water heater.
Estimated Investment: For a plant which will fabricate and assemble about 300 units per year, the required investment will be:
• Building/shade 200m2 at Birr 1500/ m2 = Birr 300,000
• Machinery …………………………………… = Birr 270,000
• Working capital ………………………….. = Birr 150,000
Total ….. = Birr 720,000
Benefits: utilizes solar energy instead of electric or other forms energy which minimizes costs, improves the standard of public hygiene and health, and introduces new technology and skills.
Location: Combolcha, Bahir Dar.