• The solar radiation incident on the surface of the earth can be conveniently utilized for the benefit of human society.
  • One of the popular devices that harness the solar energy is solar hot water system (SHWS).
  • A solar water heater consists of a collector to collect solar energy and an insulated storage tank to store hot water.
  • The solar energy incident on the absorber panel coated with selected coating transfers the hat to the riser pipes underneath the absorber panel.
  • The water passing through the risers get heated up and is delivered the storage tank.
  • The re-circulation of the same water through absorber panel in the collector raises the temperature to 80 C (Maximum) in a good sunny day.
  • The total system with solar collector, storage tank and pipelines is called solar hot water system.
  • The solar water heating systems are of two categories. They are : closed loop system and open loop system.
  • In the first one, heat exchangers are installed to protect the system from hard water obtained from borewells or from freezing temperatures in the cold regions.
  • In the other type, either thermosyphon or forced circulation system, the water in the system is open to the atmosphere at one point or other.
  • The thermosyphon systems are simple and relatively inexpensive.
  • They are suitable for domestic and small institutional systems, provided the water is treated and potable in quality.
  • The forced circulation systems employ electrical pumps to circulate the water through collectors and storage tanks.
  • The choice of system depends on heat requirement, weather conditions, heat transfer fluid quality, space availability, annual solar radiation, etc.
  • The SHW systems are economical, pollution free and easy for operation in warm countries like ours.

The basic components in home solar heating systems include:

  • Collectors to take the heat from the sun and pass it to a fluid
  • The heat transfer fluid which takes the heat from the collector for use or storage
  • Heat exchangers to transfer the heat from the fluid to a home’s domestic water.
  • Pumps to move the fluid through the collector and/or the exchanger, and sometimes to move the domestic water through the other side of the exchanger.
  • Controllers to run the pumps when there is collector heat available.

Based on the collector system, solar water heaters can be of two types.

Flat Plate Collectors (FPC) based Solar Water Heaters

  • The solar radiation is absorbed by FlatPlate Collectors which consist 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 channels or riser tubes to carry water.
  • The absorber absorbs the solar radiation and transfers the heat to the flowing water.
  • There are 60 BIS approved manufacturers of Solar Flat Plate Collectors.

Evacuated Tube Collectors (ETC) based Solar Water Heaters

  • Evacuated Tube Collector is made of double layer borosilicate glass tubes evacuated for providing insulation.
  • The outerwall 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 is now a mature technology.
  • Wide spread utilization of solar water heaters can reduce a significant portion of the conventional energy being used for heating water in homes, factories and other commercial and institutional establishments.
  • Internationally the market for solar water heaters has expanded significantly during the last decade.

Salient Features of Solar Water Heating System

  • Solar Hot Water System turns cold water into hot water with the help of sun’s rays.
  • Around 60 deg. – 80 deg. C temperature can be attained depending on solar radiation, weather conditions and solar collector system efficiency .
  • Hot water for homes, hostels, hotels, hospitals, restaurants, dairies, industries etc.
  • Can be installed on roof-tops, building terrace and open ground where there is no shading, south orientation of collectors and over-head tank above SWH system .
  • SWH system generates hot water on clear sunny days (maximum), partially clouded (moderate) but not in rainy or heavy overcast day
  • Only soft and potable water can be used
  • Stainless Steel is used for small tanks whereas Mild Steel tanks with anti-corrosion coating inside are used for large tanks
  • Solar water heaters (SWHs) of 100-300 litres capacity are suited for domestic application.
  • Larger systems can be used in restaurants, guest houses, hotels, hospitals, industries etc.

Fuel Savings :
A 100 litres capacity SWH can replace an electric geyser for residential use and saves 1500 units of electricity annually.

Avoided uitility cost on generation:
The use of 1000 SWHs of 100 litres capacity each can contribute to a peak load of 1 MW.

Environmental benefits
A SWH of 100 litres capacity can prevent emission of 1.5 tonnes of carbon-dioxide per year.

Life :15-20 years

Approximate cost : Rs.15000- 20,000 for a 100 litres capacity system and Rs.110-150 per installed litre for higher capacity systems .

Payback period : 3-4 years when electricity is replaced
4-5 years when furnace oil is replaced
5-6 years when coal is replaced

  • Though the initial investment for a solar water heater is high compared to available conventional alternatives, the return on investment has become increasingly attractive with the increase in prices of conventional energy.
  • The pay back period depends on the site of installation, utilization pattern and fuel replaced.



Money back Value For Quotation 1
EB bill Per Watts = Rs. 10.00 Per
Day Power Conception = 48
Unit EB bill Per Day = 48 * 10 = Rs. 480.00 
EB bill Per Month = 30 * 480 = Rs. 14,400.00 
EB bill Per Year = 10 * 480 = Rs. 1, 44,000.00 
Solar Inverter 10KW Setup Price = 12, 50,000.00
Money back Value = 12,50,000.00/1,44,000.00 = 8.6 Years

Money back Value For Quotation 2

EB bill Per Watts = Rs. 10.00
Per Day Power Conception = 48 Unit 
EB bill Per Day = 48 * 10 = Rs. 480.00
EB bill Per Month = 30 * 480 = Rs. 14,400.00
EB bill Per Year = 10 * 480 = Rs. 1, 44,000.00
Solar Inverter 10KW Setup Price = 12, 50,000.00
Money back Value = 11,50,000.00/1,44,000.00 = 7.9 Years

10KW Solar Setup Configuration With warranty 5 Years

10KW OFF Grid Solar Inverter - Zigor or refsol Make

8KW Poly Crystalline Solar Panels - MNRE Approval (USL, Moserbaer, LG, Surana) Mounting Structure For 10KW Panels
8 Number Solar tubular Battery = 12V, 150Ah

Cables For AC and DC 200 Meters

10KW Solar Setup Configuration With warranty 3 Years

10KW OFF Grid Solar Inverter – Power one or Vertex Make

8KW Poly Crystalline Solar Panels - MNRE Approval (USL, Moserbaer, LG, Surana) Mounting Structure For 10KW Panels
8 Number Tall tubular Battery = 12V, 150Ah

Cables For AC and DC 200 Meters .



LIGHTS Configuration:
This is a fixed indoor lighting system and consists of solar PV, module, battery and balance of systems. It is supplied under the following configuration configurations as per specifications of MNRE
*1 light * 2 lights * 1 light & fan * 2lights & 1 fan * 4lights.

This  luminaires  used  in  the  above  systems  comprise  compact  fluorescent  lamp  (CFL)  of 7W/9W/11W capacity which consume less energy but give illumination equivalent to 25 / 40 /60 W capacity conventional incandescent lamps respectively; The fan is of DC type with less than 20W rating.

One Battery of 12 V, 40 / 75 Ah capacity is also provided with SPV modules of the 37 Wp / 74 Wp as required. The system will work for about 4 hours daily, if charged regularly. The capacity and rating of different models are as follows:

Potential for use:

Cost and Subsidy:
Tentative cost of the systems range from Rs.8,000 for model-1 to Rs.25,000 for model-5. MNRE provides subsidy of 50% of cost subject to a maximum of Rs.2,500 for model-1 and Rs.4,800 for model-2 to 5.

Eligible Beneficiaries:
Individuals and non-profit institutions in rural areas

Systems installed so far:

No. Of Solar home lights installed with subsidy : 1296+5190=6486.


SPV lantern is a portable lamp. It consists of SPV module of 10 Wp capacity, rechargeable battery, Compact Fluorescent lamp (CFL) of 5 / 7 W and electronics (i.e. inverter and charge
controller). When sunlight falls on the SPV module, it is converted into DC electricity, which is stored in a battery and converted into AC electricity by the inverter and used for supplying power to CFL. If charged regularly, it can be used for 4 hours daily.

Potential for use

12,398 lanterns have been supplied in Tamil Nadu with subsidy from MNRE / State Govt.

A  lantern with  SPV  panel  of 10  Wp  costs  about  Rs.3000(tentative) each.  Subsidy  is  not available.


SPV street lighting system is a stand-alone system consisting of 74 W module, rechargeable battery, CFL lamp of 11 W, electronics (inverters & charge controller), a GI or MS pole of 4 m height above ground above for mounting the panel, luminaire and battery. When sunlight falls on SPV module, it is converted into DC electricity which is stored in the battery. This in turn is converted as AC electricity by the inverter and used for providing light.


  • It is a stand alone system and works even where there is no grid supply
  • Easy to transport and install anywhere and is suitable for remote areas
  • Provides lighting for 10 – 12 hours daily without running cost.
  • Boon to local bodies as they can save electricity consumption charges
  • No need for manual operation as it has automatic switch “on / off” facility.

Potential for use

SPV street lights are being installed by the local bodies – Panchayats, Municipal corporations etc. In large numbers by availing subsidy so as to reduce the recurring power consumption charges. Non-profit organizations can also use them for their campuses. 

Cost and Subsidy:
Tentative cost of solar street lights range from Rs.25,000/- to Rs.35,000/- depending upon period of warranty. MNRE provides subsidy of 30% of cost subject to a maximum of RS.81/watt.

No. Of systems installed in Tamil Nadu

No. Of SPV street lights installed with subsidy: 6378(6095+283). 

TEDA carried out awareness campaigns in the districts through DRDA and local bodies are coming forward to install SPV street lights in large numbers. MNRE sanctioned 3387 Nos. Of SPV street lights for 2003-04 which have been installed in village panchayats in 28 districts and 6 municipal corporations. During 2006-07, 244 Nos. Have been installed in the Districts andcorporations. Under Rural 32 Village Electrification programme of MNRE street lights have been installed in 5 districts.

New and Emerging uses of Solar PV Systems

(i)Solar Fencing
Solar Fencing is useful particularly in remote areas where elephants or other wild animals from nearby forests destroy agriculture crops. A 37 W solar panel can charge a 12 V battery and an energizer will convert the charge into 8000 V, 150 mA current. Whenever the wild animals come in contact with the fence, they get a heavy shock for 1/10 second and due to very low milli amps current  flow,  no  harm is  caused to the  animal;  but  they are  scared away.  It  can be  used particularly entry of wild animals in the farms near forest areas. It costs about Rs.1 lakh per km or Rs. 20,000 per acre. The total cost will come down with the increase in the area covered.

(ii)Solar Traps / pest catchers
Solar lanterns with some minor modifications are used as solar traps and pest controller which trap the pest causing damage to the crops. It is very useful to farmers not only as an emergency light but also for protecting the crops from pest. It costs about Rs.3 500/each.

(iii)Solar Traffic Signals
Solar powered traffic signal systems uses SPV panel to produce current, which is stored in battery and used for operating the LED signal lamps for required hours of operation.

(iv)Police wireless system in remote areas
Police Department uses batteries for continuous operation of communication equipment which is vital for linking their operations throughout the state. Solar energy can be used for charging of batteries for  more effective and  long term use  and to  reduce recurring cost. SPV charged batteries are useful for transmitters in rural /remote areas (RASI) where grid supply may not be available all the time.

(v)Telecommunication network
In remote locations which are not electrified or face frequent power interruptions, working of telecom systems would get affected. Solar charged batteries would be of great help to maintain uninterrupted operation.

(vi)Solar T.V and other devices
Solar energy can also be used for running T.V sets or radios or charging mobile phones or a fan or  any  other  electrical  appliance  depending  upon  power  required  for  these  devices.  Solar powered refrigerators can be used for storing of life saving drugs, vacancies etc in remote places.

Solar Water Pumps

A solar PV water pumping system – commonly knows as a solar pump – draws power from solar cell/modules to operate a motor pump set. Solar power pumps use specially developed and energy efficient motor pump sets to achieve higher discharge which off sets the high initial cost. A solar PV water pumping system consists of a number of solar PV modules connected in series – parallel combination to generate sufficient power to operate a motor pump. The solar PV modules are mounted on a metal frame in a manner that the mounting frame can be turned/titled to ensure that the modules keep facing the sun throughout the day. The system does not have any storage battery since power generated is used directly then and there. The SPV converts array converts the solar energy into electricity which is used for running the motor pump set. The pumping system can draw water from the open well/bore well or stream/pond or canal.

Types of Solar Power Pumps:
SPV water pumping system uses the SPV array mounted on a stand and includes one of the following motor pump sets compatible with the PV array.

  1. DC surface pump (centrifugal) or floating pumpset.
  2. AC surface or submersible pump set
    Centrifugal pumps are suitable for areas where water is available at shallow depths such as open wells / stream / ponds / canals etc. They are driven by a DC motor. The total head is 14 m and maximum suction head is 7m. Better performance in the form of higher water output can be achieved when the suction head is keep at the maximum.

Submersible pumps are recommended where water table is available at higher depth(more than 14 m). It is highly efficient and rugged multistage pump. Pumps can be conveniently place under water so as to lift water from up to 50 m depth.

The normal discharge rates of water for different types of pumps are given below:


  • SPV water pumping systems can be installed at a site completely eliminating loss of energy in transmission.
  • Can be installed to the required load of pumps up to 3000 Watts (2 hp).
  • SPV modules need only minimum maintenance and no battery is required.

Potential for Use:

SPV pumps are more suitable for remote areas with no or unreliable grid or as an alternative to diesel pumps. Some of the most popular applications are:

  1. Drinking water supply for small habitations.
  2. Horticulture farms, orchards, vineyards, gardens and nurseries.
  3. Agro forestry and plantations.
  4. Dairy, poultry and sheep farm
  5. Aqua culture, fish farming.

Cost & Subsidy

Template cost of solar water pumps range from Rs.2.10 lakhs to Rs.5.10 lakhs depending on type and capacity of pumps.

MNRE subsidy was available at the rate of Rs.81 per Watt peak subject to a maximum of Rs.50,000/- per system for community applications such as drinki8ng water are to be given priority over individuals. IREDA will provide loans to eligible users and the inter med arise at the rate of5% per annum respectively for the remaining price subject to maximum of 90% repayable in 10 years (subject to changes).

No. Of systems installed with subsidy: 285 pumps.


  • High cost of the system
  • Scope for use during day time only.



1000W = 1KW

1000KW = 1MW

1000MW = 1GW

1000GW = 1TW


KW – 

Kilowatts ME – 

Megawatts GW 

– Megawatts 

TW – 




12V, 5Ah

12V, 10Ah

12V, 20Ah

12V, 40Ah

12V, 60Ah


24V, 10Ah

24v, 20Ah

24V, 40Ah

24V, 60Ah


48V, 20Ah

48V, 40Ah

48V, 60Ah



6V, 4.5Ah

12V, 7.5Ah

12V, 12Ah

12V, 26Ah

12V, 42Ah

12V, 60Ah

12V, 75Ah

12V, 88Ah

12V, 90Ah

12V, 100Ah

12V, 120Ah

12V, 135Ah

12V, 150Ah

12V, 160Ah

12V, 180Ah

12V, 200Ah



P = VI

5W     - 6V, 12V

10W    - 6V, 12V

15W   - 6V, 12V

40W  - 6V, 12V

60W   - 6V, 12V

75W  - 6V, 12V

100W - 6V, 12V

150W - 6V, 12V

200W  - 6V, 12V, 24V

250W   - 6V, 12V, 24V

Example:         250W


P = V * I

250 = 37.68 * 8.16


W = VA * Power Factor (cos Pi)

VA = Voltage –Amperes

1000W = 1KW

KW = KVA * Power Factor (cos Pi) Inverter output power factor = 0.8

Example: 1

875Va inverter

W = VA * Power Factor (cos Pi) W = 875 * 0.8

W = 700

KW = 0.7

Inverter Maximum output Load = 700W Tube Light = 40W

Fan = 80W

1 Fan + 1 Tube Light = 120W

Maximum 6 Fan + 5 Tube Light we can run with 875Va Inverter .


  1. Bank Loan Schemes For Solar Power
  2. Bank Loan Schemes for Home Appliance
  3. Bank Loan Schemes for Industrial Appliance
  4. Bank Loan Schemes for MW Power Plant


  1. How to register the company?
  2. What all are the Document Required?
  3. TIN and CST Numbers Registration
  4. IEC Code Registration


  1. How to set up a micro or small-scale enterprise?
  2. Preliminary discussions on Business Plan.
  3. Feasibility considerations of a Project Organization on Structure / form of Enterprises (MSMEs) – Proprietary, Partnership, Co-operative Society, Private Ltd., Public Ltd. companies.
  4. Sources of Finance: Schemes for financing MSMEs by Tamilnadu Industrial InvestmentCorporation.
  5. Sources of Finance: Schemes of assistance offered by Commercial Banks.
  6. Schemes of assistance offered by Small industries Development Bank of India with specific reference to CGTMSE.
  7. TN  State Industrial Policy –  Concessions and  incentives offered  by  State  Dept. ofIndustries for new Entrepreneurs.
  8. Services of District Industries Centers; UYEGP/ NEEDS.
  9. Group   Discussion;   Presentations   by   the    participants;    Summing-up    and    review.Valedictory.