The most emerging system in the field of utilization of solar energy by saving money with low payback period. Water heating technology is the old age technology but using solar energy as a energy source is viable and ecofriendly.

1. Presentation
on
“SOLAR WATER HEATER”
Himanshu Kumar
M.Tech. (First Year)
Department of Renewable Energy Engineering

2. Introduction
India is blessed with solar energy in abundance at
no cost.
India is having high solar insolation of about 4.4-
6.6 KWh/ /day for an average of 280 sunny days
and most of that resource has been left untapped.
The highest annual global radiation is received in
Rajasthan, northern Gujarat, Tamilnadu and parts
of Ladakh region, the parts of Andhra Pradesh,
Maharashtra, Madhya Pradesh, Karnataka also
receive fairly large amount of radiation.
m²

3. Average Solar Insolation Data

4.  One of the popular cost-effective devices that
harness the solar energy is Solar Water Heating
System (SWHS).
 Solar water heating system is a commercially
viable and technologically mature product, is
existing in country for many years with
enormous potential.
Solar water heating is the direct use of solar
energy that has been practiced most extensively
in the last two decades.
The use of solar energy for heating water in
many respects quite similar to its use for heating
buildings.

5. Scope in India
India has a varying climate extending from
extreme to moderate due to its unique
geographical features.
Wood or biomass is used for heating and in urban
areas electricity or fossil fuels are used for this
purpose. This practice is either expensive or
degrades the environment.
Solar water heating system can be a suitable
alternative to meet the growing demand of hot
water in the country without exerting further
pressure on electricity or cutting of forest trees
from the forest areas.
The SWHS has the potential to save millions in
energy costs in our country.

6. Why Solar Water Heating?
Electricity or natural gas water heating Solar Water Heating
Pay 100% of hot water heating bill Eliminate up to 80% of bill
Surrender to continued rising energy costs
Enjoy a constant increasing savings in non-
taxable income
Add zero equity to your home
Increase home’s value through your
investment
Make monthly payments for hot water with
no return on investment
Profit from an income generation
opportunity that produces a monthly
positive cash flow
Contribute to air pollution and add heavy
toxic metals into the air and water
Utilize a safe, free, non-polluting energy
source—the sun

7. Basic Components of SWHS
Flat plate collector
Insulated water storage tank
Well insulated pipes connecting flat plate
collector and to the storage tank
Auxiliary heater ( for cloudy days)
Control of the system

8. Flat Plate collector
It is a device which is used to convert solar
energy into thermal energy & consists of the
following components:
Absorber
Transparent cover
Insulation
Tubes, Fins
Frame
Tilting angle: 0.9×latitude of the place

9. Insulated water storage tank
Purpose: A hot water storage tank (also hot water
tank, thermal storage tank, hot water
thermal storage unit, heat storage tank)
is a water tank that is used for storing
hot water for space heating or domestic
use
Material: Mild steel or Steel(Density:7850 kg/m³,
Thermal conductivity: 47.6 w/m ºc)
Insulation:The most common type of water heater
blanket is fiberglass insulation with a
vinyl film on the outside.

10. Properties of fiberglass
lightweight;
tight structure ;
 resistance to corrosive attacks;
superior shock and wear resistance;
cheap maintenance in service;
damage and breakage resistance;
at temperatures below zero it doesn’t become
slippery or covered with ice;
hardly bendable material;
low thermal conductivity .

11. Properties of Vinyl
Vinyl is resistant to moisture and humidity;
It is a very strong and durable plastic
material
Vinyl can be manufactured in variety of
colors, both transparent and solid;
It is low cost material
It can easily be recycled.

12. Cut-view of storage tank

13. Anti-corrosion material for tank
Material Properties
Epoxy, air dry Cost-effective, corrosion resistant coating
Epoxy, thermal cure
Excellent impact resistance, plus
corrosion and abrasion resistance
Inorganic zinc
Corrosion and weathering protection for
steel
Molybdenum disulfide
Friction protection for high pressure
loads

14. Insulated pipes
Purpose- To transport fluid to the lower header
of the collector (cold water) to the top
of the storage tank (hot water).
Material- Galvanized Iron sheet.
Properties->This material is tough and strong,
> It can be fairly easily worked (bent or
formed),
> It lasts a long time, too, because the
zinc coating (the galvanizing) inhibits
corrosion quite well.

15. Properties of glass wool
Used as insulation material for pipe connection
Density : 10-100 kg/m³
Average fiber dia. : 5.5 µm
Water content : ≤ 1%
Shrinking temperature: ≥ 250 °C
Thermal conductivity: 0.038–0.06 w/mºK
Non combustible in nature

16. Auxiliary heater ( for cloudy days)
Purpose:
 An auxiliary heater is attached in the tank to
provide supplement heat during cloudy days.
 Freezing protection during winter
season.
 Act as heat exchanger.

17. System control
Purpose: To protect the system from damage and
for efficient working.
Sensor ( In case of forced circulation system)
Control valve
Maintain the height between top of the collector
to the bottom of the storage tank 0.3 -0.4 m to
avoid reverse flow during night( in case of
natural convection system).

19. Working Principle of SWHS

20. Either by gravity flow or forced circulation, water
from the cold-water tank enters the solar tank and
fills it up.
The cold water from the solar tank in turn flows
in the bottom header pipe of the absorber, and
into the copper tubes , until all the absorber tubes
and the header at the top of the absorber are full.
When the sun rises to a certain level, its energy,
which falls on the absorber fins and tubes, begins
heating the water contained therein.
The heated water being lighter than the cold
water rises and via the top header pipe of the
absorber, flows into the top of the solar tank.

22. Types of solar water heating
system
The solar water heating systems are of two
categories:
1) Closed loop system.
2) Open loop system

23. Close loop system:
In the closed loop system, heat exchangers are
installed to protect the system from hard water
obtained from bore wells or freezing
temperatures in the cold regions.
The open loop system has two categories :
1) Natural circulation system (Thermosyphon).
2) Forced circulation system.

25. Natural Circulation SWHS
Work on the principle of
thermosyphon effect.
As water from the lower
of the tank enter into
collector plate heated up
and rises in the copper
tube column.
Hot water enter at the
top of the storage tank
via upper header of the
collector.

26. Forced Circulation SWHS
Source of cold water
supply can be at any level
as water shall be pumped
into the system.
It is recommended to use
where source of cold water
is not placed at sufficient
height and attain sufficient
water pressure and to
maintain uniform water
temperature.

27. Salient Features of SWHS
Around 60–80˚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

28. 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 anticorrosion 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.

29. The optimum size of a solar water heater system
to meet a particular service hot water need (load)
depends on the followings:
 Investment required in the solar system
 Coast of alternative (auxiliary energy)
 Collector orientation
 Climate and
 Temperature of cold water supply
Load and Sizing of the System

30. Heat storage in the system
Where,
Q= Heat storage in water (watt)
m= mass flow (kg/second)
c = Specific heat of water(1 kcal/kg ˚C or
4.187 KJ/kg ˚ k)
T1= Hot water temperature (˚C)
T2= Cold water temperature (˚C)

31. Collector Area
Average solar insolation: 5000 kcal/m² day
Collector efficiency: 30 %
Hot water demand per day: 100 litres
Tape water temperature: 15 ˚C
Hot water temperature: 55 ˚C

32. = 5000×30/100
= 1500 kcal/m² day
Specific heat of water = 1 kcal/kg˚c
Thus,
Q= 100×1×(55-15)
= 40×10² kcal

33. Protection against freezing
The collector may be designed to be drained
during times when they are not operating or
when freezing is a possibility.
Anti-freezing solution( Ethylene glycol) can be
used in the collector , with heat exchanger to
transfer energy to the water.
The collector may be covered with movable
insulation.
Through the circulation of warm liquid from the
storage tank or the operating of electric heat
strips attached to the absorber.

34. Advantages:
 These systems use solar energy which is a free and
renewable source of energy.
 In sunny and warm places with high insolation
values solar water heating system are very cost
effective.
 Relatively good payback period.
 These systems have low maintenance costs.
 Some countries even offer the option of leasing
solar water heating systems which can
significantly decrease initial costs.

35. Disadvantages:
 The main disadvantage of solar water heating
systems is relatively high upfront costs.
 In most areas they will require electrical or gas or
other fuel backup during the winter period.
 Payback times can vary greatly mostly due to
regional sun (the more insolation, the shorter
payback period).
 Relatively low efficiency of passive solar water
heating systems.
 They require excellent overheating and freeze
protection.

36. Application of SWHS
 Bathing.
 Laundry application in hotels, hospitals, hostels.
 Cooking (Pre-Heating of water helps in
reduction of use of fuel).
 Various industrial applications.

37. Solar water heater for hotel
application
Hubei, China

38. Swimming pool solar water heater

39. Conclusion
Source is abundant and inexhaustible in
nature so enjoy with free cost of energy.
Cheaper cost as compare to other heating
system.
Due to constraints on energy availability, it
is most suitable.
Keep the environment clean.