• What is solar water
• Schematic diagram
• How does it work?
• Site selection (Defining the Solar Window)
• Site Assessment Solar Window Illustration
• Site Assessment Collector Mounting
• What are different types of Solar Water Heaters?
• Flat Plate Collectors (FPC) based Solar Water Heaters
• Evacuated Tube Collectors (ETC) based Solar Water Heaters
• What happens on cloudy/rainy day? Do I still get hot water?
• Fuel Savings
• Environmental benefits
• Life & Approximate cost
• Advantages / Disadvantages
3. WHAT IS SOLAR WATER HEATER?
• A Solar Water Heater is a device which provides hot
water for bathing, washing, cleaning, etc. using solar
• 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.
5. HOW DOES IT WORK?
• A Solar Water Heater comprises of 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 thermo
syphon principle to the storage tank.
• Hot water then stored in the tank can be used for various
6. SITE SELECTION (DEFINING THE SOLAR WINDOW)
• Shortest day of the year
• Longest day of the year
• Solar collectors need full
sun from 9 AM until 3 PM
9. WHAT ARE DIFFERENT TYPES OF SOLAR WATER HEATERS?
• 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( can be
easily broken or destroyed) 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 thermo syphon systems and those with pump are
known as forced circulation systems.
10. FLAT PLATE COLLECTORS (FPC)
BASED SOLAR WATER HEATERS
• The solar radiation is absorbed by Flat Plate 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
• The absorber absorbs the solar radiation and transfers the heat
to the flowing water.
11. EVACUATED TUBE COLLECTORS (ETC)
BASED SOLAR WATER HEATERS
• Evacuated Tube Collector is made of double layer borosilicate
glass tubes evacuated for providing insulation.
• The outer wall of the inner tube is coated with selective
12. WHAT HAPPENS ON CLOUDY/RAINY
DAY? DO I STILL GET HOT WATER?
• 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
• So, you get hot water all the time even on rainy days.
13. FUEL SAVINGS :
• A 100 liters capacity SWH can replace an electric geyser for
residential use and saves 1500 units of electricity annually.
15. LIFE & APPROXIMATE COST :
• A SWH of 100 liters capacity can prevent emission of 1.5 tones of
carbon- dioxide per year.
• Rs.15000- 20,000 for a 100 liters capacity system and Rs.110-150 per
installed liter for higher capacity systems
• Simple to construct and install.
• No or negligible running cost.
• Almost maintenance free.
• Cost is low and economically competitive with electric water
• It saves time and high grade form of electric energy.
• Required low temperature up to 100o C can be achieved by
simple flat plate collector.