The document discusses various methods of harnessing solar energy, including solar heating systems, power towers, parabolic dishes, photovoltaic cells, and solar ponds. It also describes a case study of a "Solar Tuki" clean lighting alternative to kerosene lamps in Nepal. The advantages of solar energy are that it is renewable, environmentally friendly, and can provide independent power, while the main disadvantage is the high initial cost of solar systems.

1. Presented by;
Surendra Bam

2.  What is solar energy?
 Putting solar energy in use
- Solar Heating Systems
- Power towers
- Parabolic Dishes and Troughs
- Photovoltaic cells (solar cells)
- Solar Ponds
 “Solar Tuki” – a clean alternative
to “wicked” kerosene lamp (case study)
 Advantages and Disadvantages of solar energy
 Conclusion

3. Photovoltaic (solar)
panel
 Originates with the
thermonuclear fusion
reactions occurring in
the sun.
 Clean, renewable source
of energy
 Harnessed by solar
collection methods such
as solar cells
 Converted into usable
energy such as Sun and electrical
power lines
electricity
Set of solar panels

4.  Represent the
entire
electromagnetic
radiation (visible
light, infra red,
ultraviolet, x-rays
and radio waves).
 The greatest
output of solar
energy is the
visible part of
spectrum i.e. 43%

5.  Solar power
systems
installed in
the areas
defined by
the dark
disks could
meet the
world's
current total
energy
demand

6. 1. Solar Heating Systems- Two types;
a) Active solar heating system- that uses pumps or blowers to
actively circulate the air or water from the collector to desired
location.
Example:
Active
system
with water
heated by
solar
collector
and used to
supplement
hot water

7. Solar water heating system:
Efficiency of solar heating system is always less than
100% because;
a) % transmitted depends on angle of incidence,
b) number of glass sheets (single glass sheet transmits 90-
95%)
c) composition of the glass
Solar water heating saves approx. 1000 megawatts of
energy a yr., equivalent to eliminating the emissions
from two medium sized coal burning power plant.
By using solar water heating over gas water heater, a
family will save 1200 pounds of pollution each year.

8. b) Passive solar heating system- relies on natural convection current to
move the air or water.
Passive solar
Passively heated at
Colorado

9. Heating living spaces:
Best design of a building is for it to act as a solar collector
and storage unit. This is achieved through three elements:
insulation, collection, and storage.
Efficient heating starts with proper insulation on external
walls, roof, and the floors. The doors, windows, and vents
must be designed to minimize heat loss.
Collection: south-facing windows and appropriate
landscaping.
Storage: Thermal mass—holds heat.
a) Water= 62 BTU per cubic foot per degree F.
b) Iron=54, Wood (oak) =29, Brick=25, concrete=22,
and loose stone = 20.

10. 1. Power towers:
Power tower in Barstow, California

11. Power towers….
General idea is to collect the
light from many reflectors spread
over a large area at one central
point to achieve high temperature.
(like magnifying glass to focus
sunlight onto a tiny spot to burn
a hole through a piece of paper)
The intense heat generates steam from boiler to drive a
conventional turbo generator.
Example is the 10-MW solar power plant in Barstow, CA.
• 1900 heliostats, each 20 ft by 20 ft
• a central 295 ft tower

12. 2. Parabolic Dishes and Troughs:
i) Parabolic Dishes ii) Troughs

13. Parabolic Dishes and Troughs…..
Focus sunlight on a smaller receiver for each device; the
heated liquid drives a steam engine to generate electricity.
Typically, the reflector is made of thick glass silver
mirrors formed into the shape of a parabola.
Because they work best under direct sunlight, parabolic
dishes and troughs must be steered throughout the day in
the direction of the sun.
The first of these Solar Electric Generating Stations (SEGS)
was installed in California by an Israeli company, Luz
International.
Output was 13.8 MW; cost was $6,000/peak kW and
overall efficiency was 25%.

14. Silicon
 Photovoltaic cells (solar wafer
cells) are capable of directly
converting sunlight into
electricity.
Solar
 Solar cell is an electrical cells
component that work based
on photovoltaic effect.
 A simple wafer of silicon with
wires attached to the layers.
Current is produced based on
types of silicon (n- and p-
types) used for the layers.
Each cell=0.5 volts.

15. Working of PV cell:
A PV cell consists of two thin layers of semi-
conducting material. The lower layer has
atoms with valence electron; such electrons
are easily lost. This is the “p-layer”. The
upper layer has atoms lacking valance
electrons; such materials easily gain
electrons. This is the “n-type” layer.
When photons strike a PV cell, their energy
is transferred to an electron in the
semiconductor material of the cell.
so-called p-n-junction is created on
the barrier layer. The special feature
of this barrier layer is that a strong
electrical field is created locally.

16. Solar Panel Use Today
Tele com
Residential Home
Systems (2-8 kW

17. Solar Ponds
El Paso Solar Pond

18. Solar ponds…….
One way to tap solar energy is through the use of
solar ponds. Solar ponds are large-scale energy
collectors with integral heat storage for supplying
thermal energy. It can be use for various
applications, such as process heating, water
desalination, refrigeration, drying and power
generation.
The 6000-square-metre solar pond in Bhuj, the first
large-scale pond in industrial environment to cater to
actual user demand, supplied totally about 15 million
litres of hot water to the dairy at an average
temperature of 75°C between September 1993 and
April 1995.

19. Working of solar pond:
The solar pond works on a very simple principle. It is well-
known that water or air is heated they become lighter and rise
upward. Similarly, in an ordinary pond, the sun’s rays heat the
water and the heated water from within the pond rises and
reaches the top but loses the heat into the atmosphere. The net
result is that the pond water remains at the atmospheric
temperature. The solar pond restricts this tendency by dissolving
salt in the bottom layer of the pond making it too heavy to rise.

20.  It consist of :-
- 2 sets of 0.3-Watt White Light Emitting
Diode (WLED) based lamp
- 1 unit of 3 Watt Solar photovoltaic
panel.
- Built-in rechargeable batteries
 Aim was to displace kerosene wicked lamps by solar
photo voltaic based on household lighting
system (known as Solar Tuki) through the
integrated approach of community
mobilization and technological
intervention.

21. Solar Tuki…
 Developed by ECCA (Environmental Camps for Conservation
Awareness), an NGO-
2004, Piloting in 100 households
January 2005, “Light for All” campaign initiated
2007, Tech Museum Awards (category Economic
Development)(for Solar Tuki), The Tech Museum of
Innovation, California, USA
 In addition to be a rechargeable lighting system, it is also
used as a power station for radios.
 This device is relatively costly (50 US$), it is therefore
proposed in leasing or rental systems.
 This concept and technology, already successfully used in
Nepal, are proposed to be tested in Africa during the field
tests In partnership with Selco and Antenna Technologies.
ECCA-Nepal Solar Tuki movie clip
www.youtube.com/watch?v=q1LjRcVygjg

22. 1.Saves you money
a) After the initial investment has been recovered, the energy from the sun
is practically free.
b) Solar energy does not require any fuel. It's not affected by the supply
and demand of fuel and is therefore not subjected to the ever-increasing
price of gasoline.
c) The savings are immediate and for many years to come.
d) The use of solar energy indirectly reduces health costs.
2. Environmentally friendly
a) Solar Energy is clean, renewable (unlike gas, oil and coal) and
sustainable, helping to protect our environment
b) It does not pollute our air by releasing carbon dioxide, nitrogen oxide,
sulphur dioxide or mercury into the atmosphere like many traditional forms
of electrical generations does

23. c) Therefore Solar Energy does not contribute to global warming, acid
rain or smog.
d) By not using any fuel, Solar Energy does not contribute to the cost
and problems of the recovery and transportation of fuel or the
storage of radioactive waste
3. Independent/ semi-independent
a) A Solar Energy system can operate entirely independent, not requiring a
connection to a power or gas grid at all. Systems can therefore be
installed in remote locations (like holiday log cabins), making it more
practical and cost-effective than the supply of utility electricity to a new
site.
4. Low/ no maintenance
a) Solar Energy systems are virtually maintenance free and will last for
decades.
b) Once installed, there are no recurring costs
c) They operate silently, have no moving parts, do not release offensive
smells and do not require you to add any fuel

24. a) The initial cost is the main disadvantage of installing a solar
energy system, largely because of the high cost of the
semi-conducting materials used in building one.
b) Solar panels require quite a large area for installation to
achieve a good level of efficiency.
c) The efficiency of the system also relies on the location of
the sun, although this problem can be overcome with the
installation of certain components.
d) The production of solar energy is influenced by the
presence of clouds or pollution in the air
e) Similarly, no solar energy will be produced during
nighttime although a battery backup system will solve this
problem.

25.  Argument that sun provides power only during the
day is countered by the fact that 70% of energy
demand is during daytime hours. At night,
traditional methods can be used to generate the
electricity.
 Goal is to decrease our dependence on fossil fuels.
 Mitigates the effects of acid rain, carbon dioxide,
and other impacts of burning coal and counters
risks associated with nuclear energy.
 pollution free, indefinitely sustainable.
 Innovation like Solar Tuki is important because it
can be useful for those rural life which are faraway
from main power lines.