FREQUENTLY ASKED QUESTIONS

(SOLAR WATER HEATER)

Q.No.1. What is Solar Water Heater?

Ans. A Solar Water Heater is a device which provides hot water for bathing, washing, cleaning, etc. using solar energy. It is generally installed at the terrace or where sunlight is available and heats water during day time which is stored in an insulated storage tank for use when required including mornings.

Q. No.2. How does the Solar Water Heating System heat water?

Ans.The main part of the Solar Water Heating System is the Flat Plate Collector or in common 'PANEL'. Metallic strip (mainly of Copper) is coated with thin layers of Nickel and Chromium, which is called as Solar Selective Coating. This selective coating ensures highest degree of absorption of Solar Heat and least possible emission of the same. This results in optimal utilization of the Solar Heat. This component, which is the heart of any Solar Heating System, is known as Absorber Fin. In every Flat Plate Collector (panel) there are number of such absorber fins, which are connected on both sides to copper pipes known as headers. The heat collected by the Absorber Fin is transferred to the liquid flowing through the tubes / pipes. The liquid so heated becomes lighter & is pushed up by the cold water at the bottom helping it fill the Hot Water Storage Tank. Thus the cold water is continuously heated and collected in the Hot Water Storage Tank throughout the day. This is on the basis of natural thermo-siphon.

Q.No 3. Whether the water heated during day remains hot throughout the night?

Ans. The Solar Flat Plate Collector is provided with insulation, which prevents heat loss. Similarly the Hot Water Storage Tank and the pipes carrying water up-to user point are also properly insulated. This ensures minimum drop in the temperature of the hot water. As a result, you get hot water even on cold mornings.

Q.No.4. Why is the collector kept in an inclined position?

Ans. For maximum efficiency, the sun-rays should Strike the collector at right angles. For water heating applications, maximum output is required during winter when the sun is at lower altitudes. For maximum output therefore, the collectors should face south direction and be kept at an inclination equal to latitude of the place, which is around +15 to +20 degrees.

Q. No.5. What are different types of Solar Water Heaters?

Ans. Two types of Solar Water Heaters are available; one based on flat plate collectors and the other based on evacuated tube collectors. Flat plate collector (FPC) based systems are of metallic type and have longer life as compared to Evacuated tube collector (ETC) based system because ETCs are made of glass which are of fragile in nature. Both these systems are available with and without heat exchanger. They can also work with and without pump. Systems without pump are known as Thermosyphon systems and those with pump are known as forced circulation systems.

Q. No.6. What is the expected life of a solar water heating system? What does it depend upon?

The life of solar water heating system depends on the absorber, the construction of the collector, quality of hot water tank & insulation etc. As mentioned above, a M. S. tank may get rusted & start leaking after 4-5 years, thereby resulting in lot of headache & expenditure for replacement. An ideal solar water heating system should have high quality panel, stainless steel (SS 304) tank, good quality pipes of standard make & proper insulation. These things along with use of soft water ensure a long life of system. Absorbers manufactured with the existing technology go through the coating processes at 28 degree Celsius temperature. If the cold-water tank remains empty during the day (which possibility cannot be avoided completely), temperature of approximately 180 degree Celsius is created in the collector This causes the coating at the absorber to weaken. This results in the reduction of effective life of solar water heating system. In Solarizer, we heat the absorber material to 300 degree Celsius while applying the solar selective coating on it. Thus our absorber retains its efficiency and the coating even after going through the temperature of 180 degree Celsius for hundreds of hours. We believe that the solar water system manufactured according to our technical benchmark and having our absorber will have a life span of more than 25-years.

Q.No.7. Why should I go for a Solar Water Heater? What do I save from it as compared to other?

Ans. Please refer the below comparison chart

Q.No.8. What happens on cloudy/rainy day? Do I still get hot water?

Ans. If it is cloudy for a day or two, you still get warm water as water gets heated due to diffused radiation available in the atmosphere. The system, however, is either connected to an electric geyser in the house or an electrical back-up is provided in the storage tank of the system which is switched on when water is not sufficiently hot. So, you get hot water all the time even on rainy days.

Q.No.9. How do I decide about the size/capacity of the system to be installed?

Ans. For a house with one bathroom and 3 to 4 members, 100 LPD (Liter Per Day) capacity system should be sufficient. For more numbers of bathrooms, the capacity will increase accordingly due to pipe losses & more number of family members. Generally the capacity is decided based on hot water required in mornings for bathing. If the usage is in evening & at other times also, the capacity is decided accordingly.

Q.No.10. How do I assure that a good quality system is installed at my house?

Ans. Ministry has laid down some minimum technical requirements for installation of solar water heating systems in the field . These have been made mandatory for manufacturers and suppliers and are available on MNRE website. These requirements are have been prepared in such a way that even a lay man can also check them and ensure that those are being adhered to by the manufacturers/suppliers. In case any manufacturer/supplier is found not sticking to these requirements, he may be blacklisted if informed to the Ministry.

Q.No.11. Why are there complaints about the poor performance of Solar Water Heating System? What are the reasons?

Ans. There can be various reasons for poor performance of Solar Water Heating System such as

• The most important reason - Low Quality Absorber.
• The collectors are not installed properly to suit the latitude of your city.
• Dealers / installers lacking required technical knowledge about Solar Energy, not following the standards and having purely commercial attitude are responsible for this. Please ensure that dealer / installer has required knowledge.
• We being in the Northern Hemisphere, Sun is in the south most of the critical time. So the panels must be installed facing SOUTH to gather maximum heat.
• Care is not taken to ensure that the hot water does not get mixed with the cold water. Solar Water Heating System is of inadequate capacity. (Undersized System.)
• Continuous use of hot water over long period.
• Lack of adequate shadow free space for installation.
• Use of hard water having dissolved salts beyond acceptable limit causing scaling and retardation of heat transfer process.
• Inadequate head for the cold water storage tank resulting in sluggish circulation.
• Inadequate capacity cold water storage tank.
• Poor quality insulation of storage tank and pipes.
• The most important reason - Low Quality Absorber.
• Blockage of system due to sediments in the water.
• Panel top glass not clean, affecting Solar Transmittance.

Q.No.12 What are the benchmarks for selecting a Solar Water Heating system as there are number of manufacturers and dealers?

Unfortunately today there is a plethora of manufacturers and dealers without required technical know-how and having no scruples do it as a business as there is a good demand for Solar Equipments. These elements prosper due to total lack of information with the common man about the criterion for selection of good Solar Water Heating System. Similarly the habit of customers to give more weight age to only the price factor, without considering the technical features and life expectancy of the system, lands them with a poor quality system. Sometimes absence of adequate after sales service results in the entire investment getting wasted.

Solar energy is inexhaustible. Similarly Solar Water Heating System is a thing which one should have to buy once in a lifetime. Thus while selecting a Solar Water Heating System; one must evaluate the following factors before taking a decision.

• Make of the panel. (By whom it is manufactured)
• Which absorber is used in the panel? Whether the sheet and tube are welded / soldered or brazed together? Best results are obtained by TIG welded full length joint than any other method. To have the best call WESTERN CONSULTANCY
• Construction of collector box. Check whether the gaskets and grommets are of EPDM. The Hot Water Storage Tank. Ask for only Stainless Steel (SS 304/ 316 Grade), as it will mean service for lifetime. Ensure that the pipe fittings attached to the tank are also of SS 304/316 and are TIG welded. Some vendors tell interesting stories for selling systems with tanks of Mild Steel or even give SS tanks of inferior quality SS and non-SS fittings. These are normally the tactics used for showing a low price. Storage tanks other than of SS 304 of adequate thickness will tend to rust and may need a replacement after 4- 6 years costing around Rs. 6000/ for a 125 Liters. tank to be replaced by SS tank apart from the mental tension and running around. Some manufacturers use SS 202 grade, which is the Steel used normally for kitchen utensils. If this is used for tank, the tank can develop cracks any time. Some manufactures use SS 304, which is the ideal grade but use low thickness sheet. Similarly the fittings also should be of SS 304 grade. Some manufacturers use GI Fittings. Since the GI to SS welding is not proper the tank starts leaking after some time.
• Some manufacturers use inadequate / improper insulation for hot water tank. This results in water temperature getting substantially reduced over night. The insulation should be adequate. For hot water tank the cladding after insulation should be of high grade Aluminium. It should be without joints. The round cover on both sides should be of aluminum and without joints. Plastic/ Fiberglass degenerates after 4-5 years. If there is a joint, cold air enters inside and brings down the temperature of the water.
• The hot water pipe should be insulated with good quality insulation material.
• If the piping is to be done by the seller, the pipes and fittings of reputed companies having a name for quality product should be insisted upon.
• Valves should be of good quality with lifelong ease of operations.
• Hot water tank should have a facility (socket) for fitting electrical heater.
• Services the seller offers during the Guarantee Period should be examined.

Q.No.13. Are there any maintenance requirements?

Ans. Most domestic Solar Geysers don’t require a lot of maintenance, as there are no moving parts in the solar geyser. The only maintenance needed is cleaning of the glass once a month for best results. But if you live in a hard water area, the decaling process once every year is recommended.

For Industrial systems, the pumps need to be inspected at frequent intervals, check for scaling and choking periodically and replacement of some parts of the control panel, as and when required.

Q.No.14. How much do I save form solar water heating systems?

Ans. Please refer the below table

Q.No.15. Is it possible to integrate the Solar Hot water system into the design of my house?

Ans. Yes! The system can be designed into your house to fit unobtrusively on to a sloping roof, with a storage tank concealed, etc. This is best done, with the active involvement of your architect with our representative at the design stage itself, any modifications or changes later on are difficult to incorporate.