Duetorapideconomicexpansion,Indiahasoneoftheworld's fastestgrowingenergymarketsandisexpectedtobethesecond-largest contributortotheincreaseinglobalenergydemandby2035,accounting for18% oftheriseinglobalenergyconsumption.GivenIndia'sgrowing energydemandsandlimiteddomesticfossilfuelreserves,thecountryhas ambitiousplanstoexpanditsrenewableandnuclearpowerindustries. Indiahastheworld'sfifthlargestwindpowermarketandplanstoadd about20GW ofsolarpowercapacityby2022.Indiaalsoenvisagesto increasethecontributionofnuclearpowertooverallelectricitygeneration capacityfrom 4.2% to9% within25years

1. Lecture No. 9-Solar Water Heaters
• Water heating is one of the simplest
applications of solar energy.
• Hot water is required for domestic activities
like taking bath, cleaning utensils, washing
clothes and floors etc.
• Hot water is also required for industrial
activities.
• (Note: A solar water heater having capacity of
100 lit can save about 2000 units of electricity
annually.)

2. Advantages of Solar Water Heating
• Simple in construction
• Easy to install
• No maintenance
• No operating cost
• Saves time and energy for
heating water.
• Easily retrofittable to
existing houses.
• Economically viable as
compared to electric
water heater.

3. Types of Solar Water Heaters
• 1. Collector coupled to
storage tank
• 2. Collector cum storage
system

4. 1. Collector coupled to storage tank

5. 2. Collector cum storage system

6. 1. Collector coupled to storage tank
A) Thermosyphon (Natural
convection)solar water
heater system
• B) Forced flow solar
water heater system

7. A) Thermosyphon
(Natural convection)solar water heater system
• Thermosyphon type solar
water heater is used as
domestic solar water heater
in which the temperature
requirement is not more
than 70 0C.
• It consists of-
- a solar collector (i.e. front
glazing)
- black absorber
- insulated storage tank
- piping

8. • The collector is usually
placed below the water
tank. It is usually oriented
towards south with an
inclination angle equal to
latitude of the place.
• The required collector area
is about 2 m2 for 100 lit
capacity solar water heater.
• The solar radiation is
collected by the collector.
• The cold water from the
storage tank flows down to
the inlet of the collector.

9. • The absorber inside the
collector absorbs the solar
radiation and transfers the
heat to the flowing water.
• The water is heated and
rises up in the collector by
themosyphon effect.
• The hot water is collected in
the storage tank which is
insulated to avoid heat loss.
• The circulation of water
from the tank to the
collector and back to the
tank continues
automatically by the
thermosyphon effect.

10. • This type of solar water heater is also called as passive
type of solar heater because the water is circulated by
the natural convection and no external source (i.e.
pump) is used to circulate the water.

11. B) Forced flow solar water heater system
• It is also called as active type of solar heater
because the water is circulated by a pump.

12. 2. Collector cum storage system
• It consists of three main
components-
• Front glazing material (i.e.
glass)
• Absorber
• Insulated storage tank
• The radiation passes through
the glazing material which is
absorbed by the absorber
which heats the water.
• The storage tank acts as a
collector of solar radiation as
well as storage for hot water.

13. Types of collectors used in solar water heaters
Four types of collectors are used in solar water heaters
for different temperature requirements
• 1. Unglazed polymer collector (for heating of
swimming pool water)
• 2. Metallic collector with black painted
absorber(copper tube, copper sheet and copper tube
aluminum sheet etc.) for temperature up to 600C.
• 3. Collector with selectively coated metallic absorber
for temperature up to 80-850C
• 4. Evacuated tubular collector for temperature above
800C.