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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 it work?
Ans. A Solar Water Heater comprises of a or an array of solar collectors to collect solar energy and an insulated tank to store hot water. Both are connected to each other. During the day time, water in solar collectors gets heated which is either pumped or flown automatically on thermosyphon principle to the storage tank. Hot water then stored in the tank can be used for various applications
Q. No. 3 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. 4. Which type of solar water heater is suitable for different places/ category of users?
Ans. ETC based systems are cheaper than FPC based system. They perform better in colder regions and avoid freezing problem during sub-zero temperature. FPC based systems also perform good with anti-freeze solution at sub zero temperature but their cost increases. In other regions, both perform equally good.

Systems working on thermosyphon principle are simple and relatively inexpensive. They are suitable for domestic and small institutional applications, provided water quality is good and it doesn't have large chlorine contents. Forced circulation systems are generally preferred in industries or large establishments. At places where water is hard and have larger chlorine content, if FPC based system is being installed, it must be with heat exchanger as it will avoid scale deposition in copper tubes of solar collectors which can block the flow of water as well reduce its thermal performance. ETC based systems will not block the flow of water but its performance may go down due to deposition of salt contents on inner surface of glass tubes, which could be cleaned easily once in a year or so.

Q. No. 5 What is the approximate cost of solar water heater?
Ans. Cost of solar water heater depends on size and type of system installed. Smallest size of a system is 100 liters per day, which means that it can deliver 100 liters of hot water in a day at 60 C. A 100 lpd capacity system is sufficient for a family of 3-4 members and 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.

The system cost does not include the cost of cold water tank, & its stand which is required if overhead tank is not installed in a house/ building. Cost of hot water insulated pipe line also, may be extra if number of bathrooms is more than one. Additional cost towards all these components may increase by 5 to 10%.

The cost, however, does not increase linearly with increase in capacity, rather it comes down proportionately as we go for higher capacity system.

Q. No. 7 How can I avail this subsidy & get the system installed at my place?
Ans.The system can be installed at net of subsidy by following ways:
Domestic Systems

Through State Nodal Agency- Contact respective state nodal agency in your state ( list with phone no. given on MNRE website) 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.

Through Accredited Channel Partners of MNRE (List available at MNRE website)- Contact any of them and get the system directly installed from him at net of subsidy.

Institutional Systems

Through State Nodal Agency-In same fashion as above by inviting tenders and placing order to selected manufacturer

Through DGS&D rates- Details available on DGS&D website

Through Accredited Channel Partners- In same fashion as above

Q.No. 8 Why should I go for a Solar Water Heater? What do I save from it?
Ans.A 100 litre per day capacity system suitable for 3-4 people can save upto 1500 units of electricity in a year, depending on hot water used. It can also save around 140 litres of diesel in an establishment using oil fired boiler besides reducing greenhouse gas emissions in the atmosphere. Higher capacity systems will save higher amount of electricity/fuel oil besides reducing higher amount of GHG emissions.

Electricity is expensive and is not available due to power cuts in many areas when required for heating water. Solar Water Heater, since it stores hot water in an insulated tank, provides water all the time when required. Fuel oil is also expensive and creates pollution. Storing the fuel oil for long term use in commercial establishments is another problem.

  Northern Region Eastern Region Southern Region* Western Region*
Expected No. of days of use of hot water per year 200 Days 200 Days 300 Days 250 Days

Expected yearly electricity saving on full use of solar hot water (units of electricity) 1000 1000 15000 1250
Monetary savings at different prices of electricity, Rs/year
Rs. 4/kwh 4000 4000 5000 6000
200 Days 200 Days 200 Days 300 Days 250 Days
200 Days 200 Days 200 Days 300 Days 250 Days

* The use pattern and savings for southern region pertains to the typical climate of Bangalore, while those for western region relate typically to Pune climate.

Q.No.9 What happens on cloudy/rainy day? Do I still get hot water?
Ans.On cloudy days also, 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. 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.10 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 liters 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. Some useful thumb rules for estimating the hot water requirement are given below:

Application Typical Requirement of Hot Water at 60 C
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 minutes bath.
Shaving, while 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.No.11 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.

Q.No.12 Are there any maintenance requirements?
Ans.Domestic solar water heating system do not need significant maintenance requirements. Occasional leakages in the plumbing could be easily repaired by common plumbers. In case quality of water is hard, scale deposition in the collectors may result over the years. This may require de-scaling with acids for which it is best to contact the suppliers. Broken glass may also have to be replaced by the suppliers. If outside exposed surfaces are painted, the paint may have to be redone every 2-3 years to prevent corrosion of the surfaces.

Q.No.13 Any trouble shooting guide for solar water heating systems?
Ans.Some of the troubleshooting are mentioned below:

Problem faced Probable cause and remedies
No water in tap No cold water supply
Wall at the outlet of system closed
Air lock in the pipes
Water not heated at all, although cold water flow is normal Consumption of hot water may be too high; Check use points and use pattern
Collector may be shaded
No flow of water through the Collector as it might be choked due to scaling
Get it checked from the manufacturer
Water not hot enough or sufficient quantity of hot wter is not available Cloudy weather
Consumption too high
Frequent on-off of hot water tap
Collector dirty
Vapour lock in the collector which can be removed by allowing it to cool & draining the system
Partial choking of the collector
Little quantity of boiling hot water is received Vapour locking in the collector
Pinched inlet/outlet pipes

Grid Connected Solar Rooftop Systems

Q.No.1 What is a Solar Rooftop System?
Ans.In a solar rooftop system, the solar panels are installed in the roof of any residential, commercial, institutional and industrial buildings. This can be of two types (i) Solar Rooftop System with storage facility using battery, and (ii) Grid Connected Solar Rooftop System.

Q.No.2 What is a Solar Rooftop System with Storage facility?
Ans.Such rooftop system has battery as storage facility. The solar electricity is stored in the battery and can be utilized during night also when the sun is not available.

Q.No.3 What is a Grid Connected Solar Rooftop System?
Ans.In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using power conditioning unit and is fed to the grid either of 33 kV/11 kV three phase lines or of 440/220 Volt three/single phase line depending on the capacity of the system installed at institution/commercial establishment or residential complex and the regulatory framework specified for respective States.

These systems generate power during the day time which is utilized fully by powering captive loads and feed excess power to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., the captive loads are served by drawing power from the grid.

Q.No.4 Where such plants can be installed?
Ans.Such rooftop systems can be installed at the roofs of residential and commercial complex, housing societies, community centers, government organizations, private institutions etc.

Q.No.5 What is the average cost of grid connected rooftop solar systems?
Ans.The average cost of grid connected rooftop solar systems is about Rs. 80 per watt or Rs. 8.0crore per MWp capacity.

Q.No.6 What are the other fiscal incentives are available for Solar Rooftop Systems?
Ans.There are provisions of concessional import duty/excise duty exemption, accelerated depreciation and tax holiday for setting up of grid connected rooftop power plants.

Q.No.7 What efforts Government is making to providing loans for solar rooftop systems?
Ans.: Department of Financial services has instructed to all Public Sector Banks to encourage home loan/ home improvement loan seekers to install rooftop solar PV plants and include cost of system in their home loan proposals. So far, nine PSBs namely Bank of India, Syndicate Bank, State Bank of India, Dena Bank , Central Bank of India, Punjab National Bank, Allahabad Bank, Indian Bank and Indian Overseas Bank have given instructions to extend loan for Grid Interactive Rooftop Solar PV Plants as home loan/ home improvement loan.

Q.No.8 What is the size of grid connected rooftop solar system?
Ans.:The rooftop solar systems from 1 kWp upto 500 kWp or in combination can be set up on the roofs.

Q.No.9 What are the advantages of Grid-Connected Rooftop Solar System?
  • Electricity generation at the consumption center and hence Savings in transmission and distribution losses
  • Low gestation time
  • No requirement of additional land
  • Improvement of tail-end grid voltages and reduction in system congestion with higher self-consumption of solar electricity
  • Local employment generation
Q.No.10 What is the potential available in India?
Ans.: According to a study conducted by TERI, a potential of 124 GWp SPV Rooftop plants has been estimated in the country. This can be achieved through active supports from the States.

Q.No.11 Net metering
Ans.: The grid connected rooftop system can work on net metering basis wherein the beneficiary pays to the utility on net meter reading basis only. Alternatively two meters can also be installed to major the export and import of power separately. The mechanism based on gross metering at mutually agreed tariff can also be adopted.

Q.No.12 Feed-in-Tariff
Ans.:In feed-in-tariff the Government offers a tariff for purchase of the solar power generated from such plants.

Q.No.13 Among net metering and feed-in-tariff what is preferred?
Ans.:Net metering mechanism is more popular among States

Q.No.14 In case of grid failure, is there any chance for shocks to the person who is repairing?
Ans.:In case the grid fails, the solar power has to be fully utilized or stopped immediately feeding to the grid so as to safe-guard any grid person/technician from getting shock (electrocuted) while working on the grid for maintenance etc. This feature is termed as ‘Islanding Protection’.

Q.No.15 What are requirements from State to promote grid-connected rooftop solar systems?
  • States should have conducive solar policy to allow the grid connectivity
  • State Regulators have issued tariff order for appropriate tariff, net-metering/feed-in tariff and the grid connectivity, and
  • The Distribution Companies agree to allow grid connectivity and purchase the electricity on feed-in-tariff or through net metering arrangement.

Q.No.16 How many States have policies to promote grid-connected rooftop solar systems?

So far, 13 States/UTs namely Andhra Pradesh, Chhattisgarh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Punjab, Rajasthan, Tamil Nadu, Uttarakhand, Uttar Pradesh and West Bengal have notified policies that include promotion of grid connected rooftop solar systems with net metering. Regulation from the State Electricity Regulatory Commission is also required to allow net metering/ feed-in-tariff.

Q.No.17 How many States Regulators have notified orders to promote grid-connected rooftop solar systems?

20 State/UT Regulators from Andhra Pradesh, Chhattisgarh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Odisha, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, Uttarakhand and West Bengal, Andaman & Nicobar, Chandigarh, Dadra & Nagar Haveli, Daman & Diu, Lakshadweep, Pondicherry and Goa have so far issued these regulations for netmetering/gross metering

Q.No.18 What is the present status about sanctions under the grid connected rooftop solar programme?

The Ministry has so far sanctioned 361 MWp aggregate capacity of grid connected rooftop solar systems in the country of which 42 MWp have been commissioned.

Q.No.19 What are the grid connectivity levels for such systems?

The Projects under these guidelines fall within two broad categories i.e.(a) the projects connected to HT voltage at distribution network (i.e. below 33 kV) (b) the projects connected to LT voltage i.e. 400/415/440 volts (3-phase) as the case may be or 230 volts (1-phase). Accordingly, the projects may be under the following two categories.

Category 1: Projects connected at HT level (below33kV) of distribution network The Projects with proposed installed capacity of minimum 50 kW and upto 500 kW and connected at below 33kV shall fall with in this category. The projects will have to follow appropriate technical connectivity standards in this regard.

Category 2: Projects connected at LT level (400 Volts-3 phase or 230 Volts-1 phase) The Projects with proposed installed capacity of less than100kW and connected of the grid at LT level (400/ 415/ 440 volts for 3-phase or 230V for1-phase) shall fall within this category.

Q.No.20 What are the business models that can facilitate the promotion of grid connected rooftop solar systems?

There can be many possible business models, some of which can be considered are as follows:
(a).Solar installations owned by consumer. i) Solar Rooftop facility owned, operated and maintained by the consumer(s) ii) Solar Rooftop facility owned by consumer but operated and maintained by the 3rd party
(b) Solar installations owned, operated and maintained by 3rd Party . If the 3rd party implements the solar facility and provides services to the consumers, combinations could be:
i) Arrangement as a captive generating plant for the roof owners The 3rd party implements the facility at the roof or within the premise of the consumers; the consumer may or may not invest as equity in the facility as mutually agreed between them. The power is then sold to the roof owner. ii) Solar Lease Model, Sale to Grid The 3rd party implementing the solar facility shall enter into a lease agreement with the consumer for medium to long term basis on rent. The facility is entirely owned by the 3rd party and consumer is not required to make any investment in facility. The power generated is fed into the grid and the roof top owner gets a rent.
(c) Solar Installations Owned by the Utility
i) Solar installations owned operated and maintained by the DISCOM The DISCOM may own, operate and maintain the solar facility and also may opt to sub contract the operation and maintenance activity. The DISCOM may recover the cost in the form of suitable tariff. The electricity generation may also be utilized by DISCOM for fulfilling the solar renewable purchase obligation.
ii) Distribution licensee provides appropriate viability gap funds The DISCOM may appoint a 3rd party to implement the solar facilities on its behalf and provide appropriate funds or viability gap funds for implementing such facility.

Q.No.21 Which organizations are setting up the projects for end users?
Ans.:The programme is being implemented through multiple agencies for rapid up-scaling in an inclusive mode. These agencies are:
(i) State Nodal Agencies(SNAs)
(ii) Solar Energy Corporation of India (SECI)
(iii) Channel Partners:
(a) Renewable Energy Service Providing Companies (RESCOs)
(b) System Integrators
(c) Manufactures of any component of the Solar Plants
(d) Project developers
(e) Vendors/ suppliers of solar equipment
(f) Reputed and relevant NGOs of National level
(iv) Financial Institutions/Financial Integrators The Financial Institutions like NABARD, National Housing Banks, Other Banks, IREDA, SECI etc.
(v) Other Govt. Departments/Agencies The other Govt. Departments/Agencies i.e., Railways, Defense/Para Military Forces, Local Government Bodies including Municipal Corporations/Municipalities, PSUs, Institutions, Development Authorities, DMRC, State Departments interested in directly implementing the programme.

Q No.22 What are the targets under Jawaharlal Nehru National Solar Mission (JNNSM)?

The targets under JNNSM are as under:

Application Segment Target for Phase I (2010- 13) Cumulative Target for Phase 2 (2013-17) Cumulative Target for Phase 3 (2017-22)
Grid solar power (large plants, roof top & distribution grid plants) 1,100 MW 10,000 MW 20,000 MW
Off-grid solar applications 200 MW 1,000 MW 2,000 MW
Solar Thermal Collectors (SWHs, solar cooking, solar cooling, Industrial process heat applications, etc.) 7 million sq. meters 15 million sq. meters 20 million sq. meters

Q.No.23 What are the achievements against the targets fixed for Phase-I of JNNSM in solar energy?

The achievements against the targets fixed for Phase-I are as under:

Application Segment Target for Phase I (2010- 13) Achievements
Grid solar power (large plants, roof top & distribution grid plants) Grid solar power (large plants, roof top & distribution grid plants) 1686.44 MW commissioned
Off-grid solar applications 200 MW 252.5 MW sanctioned
Solar Thermal Collectors (SWHs, solar cooking, solar cooling, Industrial process heat applications, etc.) 7 million sq. meters 7.01 million sq. meter installed

Q.No.24 What is the gross potential of solar power in the country?
Ans.India is endowed with vast solar energy potential. About 5,000 trillion kWh per year energy is incident over India’s land area with most parts receiving 3-5 kWh per sq. m per day. Based upon the availability of land and solar radiation, the potential of solar power in the country has been assessed to be 750 GWp.

Q.No.25 What is the State-wise total commissioned capacity of Grid Solar Power Projects in the country so far?
Ans.The State-wise commissioned capacity of Grid Solar Power Projects in the country are as under:
Commissioning Status of Grid Connected Solar Power Projects under Various Schemes
Sr. No. State/UT Total commissioned capacity till 28-02-15 (MW)
1 Andhra Pradesh 236.86
2 Arunachal Pradesh 0.025
3 Chhattisgarh 7.6
4 Gujarat 949.05
5 Haryana 12.8
6 Jharkhand 16
7 Karnataka 77
8 Kerala 0.025
9 Madhya Pradesh 499.58
10 Maharashtra 334.4
11 Orissa 31.76
12 Punjab 119.77
13 Rajasthan 902.1
14 Tamil Nadu 111.76
15 Telangana 8
16 Uttar Pradesh 49.71
17 Uttarakhand 5
19 West Bengal 7.21
20 Andaman & Nicobar 5.1
21 Delhi 5.465
22 Lakshadweep 0.75
23 Puducherry 0.025
24 Chandigarh 2
25 Others 0.79
TOTAL 3382.78