Question: What is a solar water heater?

Answer: A solar water heater uses the sun's energy rather than electricity or gas to heat water, thus reducing your monthly utility bill. When installed properly, solar water heaters are more economical over the life of the system than heating water with electricity, dedicated heat pumps, heat recovery units or propane

The direct circulation system circulates potable water from the water storage tank through one or more collectors and back into the tank. The solar collector is the main component of the solar system. It is usually a box with insulation and a black absorber plate that collects solar radiation and heats the water.

In integral collector storage systems, the solar water storage system is built into the collector. The potable water in the collector unit is heated by the sun and delivered by city or well water pressure to an auxiliary tank (which contains non-solar back-up heating) or directly to the point of use.

A thermo siphon solar water heating system has a tank mounted above the collector (normally on the roof) to provide a natural gravity flow of water. Hot water rises through piping in the collector, which is mounted below the tank; heavier cold water sinks to the lowest point in the system (the collector), displacing the lighter hot water which rises to the tank.

Question: How does a direct circulation solar system work?

Answer: As sunshine strikes the collector, the water inside it is heated. During periods of insufficient sunshine or high hot water demand, a backup electrical element in the storage tank heats the water. The check valve prevents heat loss when the circulating pump is off or with the flow of water mounted over the collectors.

Question: What size solar system do I need?

Answer: For a family of four, 2500x1500x2500mm of collector and a total tank storage of 125 ltrs. are typical. It must be noted that thermo siphon systems will include two tanks, the solar system tank as well as the auxiliary tank.

Add on Solar systems electrically-assisted can also be procured ,electrically-assisted system that uses a 2 K.W or 3 K.W electrical loads retrofitted. which can be useful for the non sunny days or increased demand for hot water supply.

Question: How much do I save?

Answer: Your monthly savings will depend on the amount of hot water you use, storage tank size and type and price of fuel used for backup water heating . For a family of four, the typical hot water usage is 100-litres per day, thus using 1530-kilowatt-hours per year to heat the water electrically, or Rs.7420/-(considering 300days for usage) per year worth of electricity at Rs.4.85/- per kilowatt hour.

A solar water heater should save between 50% and 85% of the hot water portion of the monthly utility bill, or Rs.7500/- to Rs.8500/- per year for a family of four.

A solar water heater can save even more if you turn off the backup and rely solely on the sun for your hot water. During summer months, when hot water demands are lower and the sun shines longer, most solar owners turn off the backup element circuit breaker, or switch. As electricity and other fuel prices go up, solar savings will increase accordingly.

Question: Do I have to change my habits to use a solar water heater?

Answer: No. Solar water heaters could always be installed with a backup heating system in the storage tank to ensure that hot water is available at all times. However, to maximize solar utilization and your savings, you should attempt to use the most hot water in the late morning and early afternoon when the solar system is operating at its peak due to the available sunshine. Also, your solar system will be more effective if your use of hot water is spread more evenly over the week . For example, if you use hot water for laundry, instead of washing seven loads of clothes in a single day, wash one load each day. This will reduce the amount of backup energy required for your solar system.

Question: How do I finance a solar water heating system?

Answer: The best way to finance a solar energy system is to include it as part of your home mortgage. In long-term loans of 20 years or more, the monthly solar savings will normally be greater than the monthly mortgage payments for the solar system.

If you are buying an existing home with a new mortgage, you may be able to include a new solar water heater in the mortgage. Check with your local lending office. Also, many lending institutions such as Nationalized banks offer short-term loans for solar systems, based upon the applicant's personal credit rating.

Question: What kind of a solar collector should I buy?

Answer: A basic flat-plate collector consists of a metal/thermo-plastic enclosure, an absorber plate and flow tubes, insulation, and a glass/Myler sheet covering. Flat-plate collectors can be 2 to 4 feet wide, 5 to 12 feet long, and 4 inches thick. The absorber takes in the sun's energy, which is then transferred in to the water flowing through the collector panel. all flat-plate collectors generally have insulation behind the absorber plate to reduce the heat loss and a glass cover/myler sheet on the front, facing the sun. Some edge insulation inside the enclosure box is also supplied.

Question: What is the proper orientation of the solar collector?

Answer: Collectors should be mounted on an un-shaded area of a south-facing roof. They can face up to 45 degrees east or west of south without a significant decrease in performance. Collectors mounted in this manner are more aesthetically pleasing. However, for flat or very low-sloping roofs, collectors should be tilted at an angle (to the horizontal) that is approximately equal in degrees to the local latitude. Since the sun is lower on the horizon during the winter months, tilting the collector at an angle up to 15 degrees greater than latitude will increase winter performance, which is desirable in most cases.

Question: How do I protect my solar system?

Answer: Flush-type prevention valves are being used. These valves open when the water temperature in side the tank approaches to the the 80 degree centigrade level. Water pressure forces water from the storage tank through the collectors and out through the valve. The valve closes when the water leaving the valve reaches 75 0 C.

Another method of protection is achieved by water re-circulation. Consistent use of solar collector at high temperatures may acquire scaling due to oxidation of hard water components such as magnesium, sodium etc., depending on the level of water hardness from the bore well. When the scaling components are high, temperature through solar collectors might drop. The undue scaling can be cleaned with a pump to circulate high pressure clean water or adding dilute HCL through the collectors. A second level of protection in this system, is provided by drain valves that manually drain the collector. Manual protection alone may be adequate for conscientious homeowners in areas where hard water are frequent .

What's more, because there are no moving parts, there's little to break down. These systems last a long, long time.

Question: Are solar water heating systems reliable?

Answer: Properly designed and installed systems with glass-covered/myler sheet collectors should perform well for more than 8 to 10 years . Controllers, like other electronic devices, may require servicing during the life of the system, and hot water tank may have to be replaced after 10 years. Since conventional water heaters have the same expected lifetime, water tank replacement costs are not regarded as unique to solar energy systems.

Normal maintenance consists of checking pipe insulation, roof penetrations and collector mounting, and tank flushing . The latter is also recommended for conventional water heating systems, as is periodic replacement of the water heater sacrificial anode rod.

Question: What other ways are there to save on water heating bills?

Answer: Besides simply using less hot water, and timing solar-heated water use to peak when the solar exposure is at its peak, the following strategies are suggested:

Finally, in a one-tank solar system, it's a good idea to have the back-up element controlled by a timer or manual on/off switch to keep it from coming on during the day. This strategy allows the solar system to produce all the hot water without the back-up heater being activated.