| Q1. |
WHAT IS SOLAR THERMAL WATER HEATING SYSTEM? |
| Ans. |
Solar Water Heating System is one of the widely used solar system by which we get hot water with the help of solar radiation for domestic, industrial application etc. Solar Water Heating System which converts Solar Energy into Thermal Energy and can replace any type of conventional heating system / fuel for thermal application like water heating, air heating etc. |
| Q2. |
HOW DOES IT WORK? |
| Ans. |
Solar Water Heating System consists of solar collector, insulated hot water storage tank, insulated pipings, control and instrumentation etc. Solar Energy incident on the absorber panel coated with selected coating transfers the heat to the water flowing in the riser pipe underneath the absorber fins. The water passing through the raiser is then delivered to the insulated storage tank and the same water is re-circulated through the collector throughout the day till the maximum temperature is achieved |
| Q3. |
WHAT DOES IT SAVE YOU? |
| Ans. |
- Solar Water Heating System (SWHS) operates on solar radiation which is freely available thorough out the year. This saves expenditure on conventional fuel like coal, firewood, diesel, electricity etc.
- Solar Water Heating System (SWHS) is absolutely maintenance free system which can save time and money.
- SWHS is a pollution free system which can save the environment of GHG emissions.
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| Q4. |
WHERE WE CAN USE SOLAR WATER HEATING SYSTEM? |
| Ans. |
Hotel industries, Educational Institutions, Hostels, Hospitals, Dairy Industries, Canteens, Boiler pre-heating application etc. Wherever we need hot water for any application like bathing, vessels cleaning, drinking, cooking etc we can use this system without any fuel cost.
The solar water heating systems are also used in the process industries where the boiler supplies low pressure steam. Solar water heating systems are generally used as an excellent energy conservation and energy efficiency equipment by supplying hot water at 80 deg.c. to boiler at pre-heater stage.
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| Q5. |
WHAT IS THE CAPACITY OF SOLAR WATER HEATING SYSTEM AVAILABLE IN THE MARKET? |
| Ans. |
It is available from minimum 100 LPD (Litre per day) Capacity for both domestic and commercial application. It can deliver hot water at 60 Deg. C for domestic application and 80 Deg. C for commercial application.
It is available in the multiples of 100 litres in the market. For 100 LPD (Litre per day) Capacity Solar Water Heating System, we need 1 no. of Solar Collector of 2 sq. mtr area. It requires 4 sq. mtr shadow free area for installation on the roof.
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| Q6. |
WHAT ARE THE DIFFERENT TYPE OF SOLAR WATER HEATING SYSTEM AVAILABLE? |
| Ans. |
Solar water heating system can be classified in 2 types based on the collector system.
a) Solar water heaters based on Flat plate Collectors.
b) Solar water heaters based on Evacuated Tube Collectors.
Flat plate Collectors:
In this type, solar radiation is absorbed by flat plate collectors which consists of an insulated outer metallic box covered on the top with glass sheet. Inside there are blackened metallic absorber (selectively coated) sheets with built in riser tubes to carry water. The absorber absorbs the solar radiation and transfers the heat to the flowing water.
Evacuated Tube Collectors:
In this type, solar collector is made of double layer borosilicate glass tubes evacuated for providing insulation. The outer wall of the inner tube is coated with selective absorbing material. This helps absorption of solar radiation and transfers the heat to the water which flows through the inner tube.
Solar water heating system also classified in 2 types based on the circulation of water.
a) Thermosyphon system.
b) Forced flow or forced circulation system.
Thermosyphon system:
In the thermosyphon system, water comes from the over head tank to bottom of solar collector by natural circulation and water circulates from the collector to storage tank as long as the absorber keeps absorbing heat from the sun and water gets heated in the collector. The cold water at the bottom of storage tank run into the collector and replaces the hot water, which is then forced inside the insulated hot water storage tank. The process of the circulation stops when there is no solar radiation on the collector. Thermosyphon system is simple and requires less maintenance due to absence of controls and instrumentation.
Forced circulation system:
In the forced flow system, a pump is used for circulating water between the collectors and the insulated hot water storage tank. The forced flow systems are more efficient as compared to thermosyphon systems due to higher flow rate. Generally, the pumps are operated by differential temperature control (DTC) system, which senses the pre-setting temperature difference between inlet and outlet of the collectors.
Solar water heating systems are also further classified as Direct System (Open Loop System) and Indirect System (Closed Loop System).
Open Loop System:
The Direct System is the one where the water circulates through the entire system i.e. collector to storage tank and the same hot water is used for various applications. These type of systems are generally not suitable for hard water due to the scaling problems in the risers and headers of the collector.
Closed Loop System:
In the Indirect System, the thermic fluid is circulated between the collector and the insulated storage tank with heat exchanger. The heat from the thermic fluid is then transfer to the water through heat exchanger in the storage tank. In this system, the thermic fluids are not in physical contact with the water in storage tank. These systems are generally suitable for hard water.
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| Q7. |
IS THERE ANY SOFT LOAN / SUBSIDY AVAILABLE? |
| Ans. |
Yes, soft loan is available from Indian Renewable Energy Development Agency Limited (IREDA), New Delhi under MNES Interest Subsidy Scheme. Loan can be extended for both domestic and commercial application for any capacity of Solar water heating system. The principal with the interest is repayable in 6 years (including one year moratorium period).
Ministry of Non Conventional Energy Sources (MNES) is providing Interest Subsidy to promote the solar water heating systems through IREDA and few Nationalized Banks so that end users/ customers can take soft loan at lesser interest rate.
Apart from the above, few states are providing additional subsidy to promote the solar water heating concept and made mandatory for certain buildings, government buildings etc. to use solar water heating systems.
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| Q8. |
WHAT IS THE MINIMUM LOAN ELIGIBILTY FROM IREDA? |
| Ans. |
IREDA is providing soft loan under two different categories. One is Direct User scheme and other is Intermediary scheme.
Direct User scheme: The end user/ customer who wish to install larger capacity solar water heating system can approach directly IREDA to avail IREDA soft loan facility. Minimum loan amount eligible for sanction under this category is Rs.5.00 lakhs.
Intermediary scheme: Any Financial Institutions, Banks, Solar Thermal Manufacturers, Corporate Bodies, NBFCs, State Nodel Agencies, Reputed NGOs can become intermediary of IREDA for on-lending soft loan to different end users for different kind of application. Minimum loan amount eligible for sanction under this category is Rs.10.00 lakhs.
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| Q9. |
WHAT IS THE PERFORMANCE GUARANTEE FOR SOLAR WATER HEATING SYSTEM? |
| Ans. |
Under IREDA soft loan/ MNES Interest Subsidy scheme, Solar Thermal manufacturers are required to provide 5 years warrantee/ guarantee for complete solar water heating systems. Few manufacturers are providing 10 years guarantee for Solar Collectors.
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| Q10. |
What is the interest rate applicable for the sector? |
| Ans. |
Please refer enclosed Annexure – I for the detailed interest rate applicable for the different category of customers under Solar Thermal sector. |
| Q11. |
WHO ARE THE MANUFACTURERS AND SUPPLIERS OF SOLAR WATER HEATING SYSTEMS? |
| Ans. |
Please refer IREDA’s Brochure No. 3 or enclosed Annexure – II for the BIS approved manufacturers list under Solar Thermal sector.
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Annexure - I
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Annexure - II
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