Electrical Directory

FAQ: Solar Water Heater

Q. What is comparison between ETC and FPC based systems?

Q. What is comparison between ETC and FPC based systems?

 S.No

       Evacuated Tube Collector

       Flat Plate Collector

1

Quick heat generation

Slow heat generation

2

Satisfactory performance even in extreme cold condition (-18 deg. C)

Freezing of water will take place at high altitude causing damage to the collector

3

Temperature range from 60deg. to 120 deg

Temperature range from 60 deg. to 80 deg

4

Heat exchanger not required

Heat exchanger required

5

Advanced technology at competitive prices that is System Cost per unit water is low

Old technology at higher prices

6

It is very easy to replace glass tube

Difficult and expensive to replace glass sheet

7

It has low maintenance

Its required high maintenance

8

Heat loss in the tubes during the daytime is

negligible (evacuated tubes)

Heat loss in the tubes during the daytime is

negligible (evacuated tubes)

9

Hot water availability for 350 days in a year

Hot water availability for 300 days in a year

claimed

10

System life above 15 years.

System life above 15 years.

Q. How is the Solar Hot Water System specified? What is LPD?

Q. How is the Solar Hot Water System specified? What is LPD?

The capacity of a solar hot water system is specified is LPD. It is a short form for Liters Per Day. The intensity of solar radiation varies throughout the day, hence capacity cannot be specified in terms of hourly output.

Q. What are the benefits of solar water heaters?

Q. What are the benefits of solar water heaters?

i.Firstly, we can save money on electricity bill.

ii.Solar water heaters help to avoid carbon dioxide, nitrogen oxides, sulfur dioxide, and the other air pollutants can help in slowing down the pace of global warming.

iii.Solar water heaters can assist in reducing this country's dependence on foreign oil.

iv.Longer than standard gas or electric storage water heaters.

Q. What are the desirable characteristics of hot water stora...

Q. What are the desirable characteristics of hot water storage tank?

The desirable characteristics of hot water storage tank are,

i.The hot water storage tank in domestic solar water heating systems is typically a double walled tank.

ii.The space between the inner and the outer tanks should be insulated to prevent heat losses.

iii.The inner tank is generally made of copper or stainless steel for longer life.

iv.The outer tank could be made of stainless steel sheet, painted steel sheet or aluminum.

v.The capacity of the tank should be in proportion to the collector area used in the system. A commonly used thumb rule is to provide 50 liters of storage for every sq. m of collector area. Too large or too small tanks reduce the efficiency.

Q. How long will the water heated by solar energy remain hot...

Q. How long will the water heated by solar energy remain hot in the tank?

Hot water produced by the solar heating system during the day is stored in an insulated storage tank. The insulation of the tank is such that water remains hot for around 24 hrs without significant drop in temperature.

Q. Can the system be installed somewhere other than on the r...

Q. Can the system be installed somewhere other than on the roof?

The system can also be installed on a bracket on a south facing wall, close to the bathrooms. However, the installation is difficult and leads to extra cost. Access to the system for repairs should also be ensured. In such installations Cost of hot water distribution piping could be reduced as the system will be close to the use point. 

Q. What would happen if water supply to the solar water heat...

Q. What would happen if water supply to the solar water heating system is irregular?

In case if cold water is not available continuously, a separate cold water tank of equal capacity has to be installed. A regular cold water supply, at a height of around 2.5 m is necessary for the system to function efficiently. 

Q. How much area is required for the installation of Solar W...

Q. How much area is required for the installation of Solar Water Heating System?

The ETC based Solar Water Heating System requires very less area for installation. For example, for a 100 LPD system suitable for a small family of 3 to 4 persons, about 30 sq ft area is required. And 380 LPD system occupies 80sq ft area.

Q. Are additional geysers required after installation of Sol...

Q. Are additional geysers required after installation of Solar Water Heating System?

If the Solar Water Heating System has inbuilt option of electrical back-up, no extra geysers are required. 

Q. How do I assure that a good quality system is installed a...

Q. How do I assure that a good quality system is installed at my home?

There are some minimum technical requirements for installation of solar water heating systems in the field. These have been made mandatory for manufacturers and suppliers. Click here for more details

Q. What capacity water heaters do I require?

Q. What capacity water heaters do I require?

Bathing Consumption               System Capacity

3 --- 4  members                           100 ltrs per day

5 --- 6  members                           125 ltrs per day

6 --- 7  members                          150 ltrs per day

8 --- 9  members                           200 ltrs per day

9 ---10 members                          250 ltrs per day

12--15 members                           300 ltrs per day

18--20 members                           400 ltrs per day

23--25 members                           500 ltrs per day

38--40 members                           800 ltrs per day

50--55 members                         1000 ltrs per day

Q. How do I decide about the size/capacity of the system to ...

Q. How do I decide about the size/capacity of the system to be installed?

Generally the capacity is decided based on hot water required. For example in a house with one bathroom and 3 to 4 members, 100 liter per day capacity system should be sufficient.

Some useful thumb rules for estimating the hot water requirement are given below:

                           Application

Typical Requirement of Hot Water at 600C

Household bathing using buckets

10-20 liters per person per bath.

Household bathing using shower with a mixing tap

20-30 liters for 10-15 minute bath

Shaving, while a tap runs

7-10 liters

Household bathing in bathtub (one filling)

50-75 liters

Wash basin with a mixing tap (hand wash, brushing of teeth, etc.)

3-5 liters per person per day.

Kitchen washing

2-3 liters per person per day.

Dishwasher

40-50 liters per wash cycle

Clothes washing machine

40-50 liters per cycle

Q. What happens on cloudy/rainy day? Do I still get hot wate...

Q. What happens on cloudy/rainy day? Do I still get hot water?

 On cloudy days, if it is for a day or two, you still get warm water as water gets heated due to diffused radiation available in the atmosphere. Otherwise the system should be connected to an electric geyser or an electric back-up to get regular hot water. 

Q. Which type of solar water heater is suitable for differen...

Q. Which type of solar water heater is suitable for different places/ category of users?

1. Colder regions:

   i. ETC systems perform better in colder regions. FPC based systems also perform well. But the FPC based systems are costlier than ETC based systems

   ii. In other regions, both perform equally good.

2. Domestic:

   i. Systems working on thermosyphon principle are suitable for domestic and small institutional applications, provided water quality is good and it doesn’t have large        chlorine contents.

3. Industrial:

  i. Forced circulation systems are generally preferred in industries or large establishments.

4. Places where water is hard and have larger chlorine content

  i. If FPc based system is being installed, it must be with heat exchanger.

  ii. ETc based systems will not block the flow of water but its performance may go down due to salt contents on inner surface of glass tubes, which could be cleaned    easily once in a year or so.

Q. How many hours are required to heat the water?

Q. How many hours are required to heat the water?

Normally, 6 to 7 hours of normal solar radiation is required to heat the water up to 60°C.

Q. In India sunny days will be available for 300-325 days in...

Q. In India sunny days will be available for 300-325 days in year. How about the rest of the days?

Every SWHS will be provided with auxiliary back up heating system by Electrical heater at extra cost.

Q. What types of pipelines are to be used in solar water hea...

Q. What types of pipelines are to be used in solar water heater?

The pipe lines used must be Galvanized steel pipes of class "B" for cold water line & precast PUF insulated. For hot water lines HDPE Pipe with "B" class Galvanized pipes are to be used.

Q. Can any type of water such as municipality treated water,...

Q. Can any type of water such as municipality treated water, bore well water or tank water is used?

Only soft and potable water. Otherwise hard water with special jacket type heat exchanger or with softener.

Q. What is the maximum possible temperature it could attain ...

Q. What is the maximum possible temperature it could attain & depends on what factors?

About 60 to 800 C. The rise in temperature depends on:

- Solar Radiation

- Weather Conditions

-No. of Solar collectors.

Q. How much money do we have to spend for maintenance?

Q. How much money do we have to spend for maintenance?

It requires very little amount as the maintenance is negligible.

Q. Is there any maintenance required for SWH systems?

Q. Is there any maintenance required for SWH systems?

Solar Water Heaters requires very little maintenance. Maintenance involves wiping the dust deposited on the glass surface once in 5 days. This helps in increasing the efficiency of the system. Other important thing is to fill up the main cold water tank up to level from which water is supplied to solar tank. It involves Periodic glass cleaning and Check for leakages and valve functioning, if any. 

Q. How does one identify a good solar water heater?

Q. How does one identify a good solar water heater?

The basic requirement for a good solar heater is that it should have sufficient collector area for the claimed capacity. Typical flat plate collectors made in the country have an area of around 2 sq. m and heats around 100 liters of water in a day. This proportion serves as a benchmark.

Further, the collectors should use good materials and the absorbers should carry a good quality coating.

Q. What are the site requirements for installation of a sola...

Q. What are the site requirements for installation of a solar water heating system?

The basic requirement for functioning of a solar system is unobstructed sunlight.

Generally, domestic solar water heating systems are installed on the roof of the house. Further,

  1. The collectors of the system have to be oriented due south for maximum interception of sunlight.
  2. The best area is flat, because it should be away from rain water drains as far as possible.
  3. Close to the bathrooms where hot water is to be supplied.
  4. Cold water should be available at the height of around 2.5 m from the base of the system.
  5. The requirement of shadow free area is around 3 sq. m for each 1 x 2 m collector used.

Q. What is the expected life of a solar water heater?

Q. What is the expected life of a solar water heater?

The expected life of solar water heater is for 15-20 years depending upon maintenance and other factors if it is made as per BIS specifications.

Q. What is the payback period?

Q. What is the payback period?

 Payback period depends on below factors. But it is a sizable amount, which is as high as 40% of an average household’s electricity bill. But on an average, the payback period is   about 3-4 years when electricity is replaced, 4-5 years when furnace oil is replaced, 5-6 years when coal is replaced.

Q. What is the procedure for release of subsidy under NABARD...

Q. What is the procedure for release of subsidy under NABARD scheme?

i.The entrepreneurs/eligible organizations have to apply to the bank for sanction of the project. The bank shall appraise the project as per their norms.

ii.If found eligible, the bank will sanction the loan excluding the margin subject to technical feasibility and financial viability.

iii.The ministry will provide 30% subsidy and 50% loan of the benchmark cost to the beneficiary through NABARD.

iv.After the satisfied field visit of installation unit, the bank will arrange to make payment directly to the supplier.

v.After sanction of the loan including subsidy, the bank shall approach NABARD for capital subsidy in the specified format.

vi.NABARD will release the subsidy subject to the admissibility of the claim.

Q. what is the present benchmark cost for solar water heatin...

Q. what is the present benchmark cost for solar water heating system under NABARD scheme?

Benchmark Cost: ETC based systems: Rs. 10,000/ sq. m., FPC based systems: Rs. 11,000/ sq. m.

Q. What is the format for project proposal for installation ...

Q. What is the format for project proposal for installation of solar water heater system?

Download the application format for project proposal from our website or MNRE site.

Q. What is the application format for availing subsidy throu...

Q. What is the application format for availing subsidy through JNNSM scheme?

The application formats to avail subsidy through JAWAHARLAL NEHRU NATIONAL SOLAR MISSION scheme are given as Annexure I, Annexure II.  

Q. How can I avail the subsidy?

Q. How can I avail the subsidy?

The system can be installed at net of subsidy by following ways:

i.Through State Nodal Agency- Contact respective state nodal agency who will visit the site, provide information on cost, size & other details of system required and get it installed at net of government subsidy through some manufacturers. List 1

ii.Through Accredited Channel Partners of MNRE - Contact any of them and get the system directly installed from him at net of subsidy.List-2 List-3 

Q. Is there any subsidy available from Government?

Q. Is there any subsidy available from Government?

Yes, the Government provides subsidy to the below extent:  

CENTRAL GOVT Subsidy:

  1. In General category states: 30% capital subsidy or loan at 5% interest on 80% of the benchmark cost for all types of beneficiaries.
  2. In Special category states:

i.For domestic & non commercial categories: 60% capital subsidy or loan at 5% interest on 80% of the benchmark cost.

ii.For commercial user category: 30% capital subsidy or loan at 5% interest on 80% of the benchmark cost.

STATE GOVT Subsidy:

  1. State government provides 20% additional subsidy for capacity up to 200 LPD for residential sector.
  2. Full subsidy minus the eligible Central subsidy will be provided for Systems in respect of Government Hostels and residential schools which are on the Government building only. 

Q. What is the approximate cost of a solar water heater?

Q. What is the approximate cost of a solar water heater?

Cost of solar water heater depends on size and type of system installed. For example, smallest size of a system is 100 liter per day, where it can deliver 100 liters of hot water in a day at 600 C which is sufficient for a family of 3-4 members. It may cost Rs. 15,000 to Rs.22,000 in planes depending on the type of system. In hilly & N-E region, the cost may be 15 to 20% more. For more details CLICK HERE

Q. What are different types of Solar Water Heaters?

Q. What are different types of Solar Water Heaters?

There are two types of Solar Water Heaters available.

I.One is flat plate collectors (FPC) and Flat plate collector based systems are of metallic type and have longer life.

I.The other based on evacuated tube collectors (ETC). ETCs are made of glass which is fragile in nature. 

 

Q. What is Solar Water Heater?

Q. What is Solar Water Heater?

Solar Water Heater is one of solar system applications, with this we get hot water with the help of solar radiation. It converts Solar Energy into Thermal Energy. 

If you have any queries please write to us info@epowerone.com or post here.

Password Assistance

Please provide your registered Email Id, We will send you the New Password.