Sunlight is freely available across the
world and is abundant, which would last at least till the
end of humankind itself if not more. The rays of sun give
heat to the earth. It helps us to live, helps in through
the process of photosynthesis.
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
The sun is the most important aspect
of life on earth - without the sun there would be no light,
seasons, winds, rain, plants, animals or life
The Process of converting sunlight into
useful electricity using semiconductor technology is referred
to as Solar Photovoltaic
There are two technologies based on solar
energy resources
Here solar energy is converted into electricity using solar
cells. Solar cells cannot store any type of energy, but
only when solar cell gets solar energy. During the night,
solar cell does not work.
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
It is the use of vapor power cycle that requires the concentration
of solar energy to reach high temperatures. Here the sun
heats a fluid like liquid metal or sodium. The fluid then
transfers its heat to water to make steam, which is then
used to generate power just like in coal or nuclear power
plants.
What is a Photovoltaic Cell?
The energy generator in PV system is the solar cell. Mostly
solar cells are thin wafers of silicon. These cells when
connected in a series and parallel constitute a solar panel.
The two types of solar cells are - Crystalline silicon cells
and thin-film cells.
Solar is made from different lots of
material, but the most common source is silicon, which is
obtained from sand. It is a semi-conductor. Silicon is also
used to manufacture computer chips. The manufacturing process
is similar to that of computer chips. But solar chips are
much more cheaper than the computer chips.
Conversion of Sunlight to Energy
Solar radiation has energy particles called Photons. When
the photons fall on the surface of solar cells they give
energy to electrons. Due to this energy the electrons break
their covalent bond and start moving freely. When the electrons
start moving in the circuit, the current starts flowing.
As a result of this movement, electricity is generated.
The voltage of each solar cell is between 0.45 to 0.5 volts.
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
Understanding Solar Panels and
Array
When various solar cells are joined togather either in series
or in parallel are called modules. Joining 36 cells togather
in series gives an output of 16-17 volts, which is sufficient
to re-charge a battery of 12 volts. Similarly, 18 cells
joined in series can recharge a 6 volts battery. In order
to protect the solar cells, they are supported with tedler
EVA and are laminated with glass. In case of higher power
needs, 2-3 modules are connected electrically to make a
Panel. If more energy is needed panels are joined togather
electrically to Arrays. In case of higher power needs, 2
or more number of modules are connected togather electrically,
this arrangement is called as arrays
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
Some of the general applications
of PV systems to provide power are:
Water Pumping
House Lighting
Street Light
Railway & Road traffic signals
Vaccine refrigeration
Telecommunication
Battery charging
Navigation Systems
Devices installed on space ships and satellites
|
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
Solar lantern
Most of the solar lanterns available in the market have:
7W Compact Flourecent Lamp (CFL)
Gives light output equivalent to a 40W incandescent
bulb
Needs 12 V, 7 AH maintenance and spill proof lead
acid battery
Panel is generally of 10 Wp
Operates for 3 hours daily
Battery life is 2-3 years
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
Solar home systems are mainly used for
lighting but can also provide electricity for small loads
including lights, radio, TV and small appliances.
Consists of a single, roof-mounted module, a simple
charge controller, a 12 - V battery and fixtures for the
loads
Each of the two 9 W CFL lamps can give light equivalent
to 60 W incandescent bulb
Needs 12 V, 40 AH low maintenance lead acid battery
Topping up of distilled water is required in the
batteries from time to time, if properly maintained the
batteries can last for 5 years or more
Water pumping with solar energy can be used for providing
drinking water to many communities with populations in the
range of 1000 to 2000 persons.
There are two types of pump specifications:
Surface Centrifugal Pump
Deepwell Submersible Pump
Installation
Some of the aspects to be kept in mind for Site selection
for SPV installation are:
Installation should be done in a shadow free area
Panel should face south in northern hemisphere and north
in southern hemisphere
Panel should be mounted on tracker to face sun continuously
to increase output up to 25%. (illustration). As this is
not possible all the time, instead the fixed panel could
be squarely facing the sun.
Lesser the angle more the output in summers while greater
the angle of panel in winters the better the output.
Latitude of the place – in winters 10 degrees to be
added to the latitude while in summers 10 degrees to be
subtracted to receive maximum solar insolation.
Equatorial/ tropical places – tilt angle at least 10
degrees in order to ensure good run-off to keep panels clean
and for better cooking
 |
Source: Rural Electrification,
the Panchayat way: Multi media CD;
Ministry of Panchayati Raj, Government of India and
The Energy and Resources |
The Solar module has to be cleaned properly fo dust
and dirt
A module should be installed on shadow free area
The battery has to be maintained properly
In Case of a wet battery, distilled water must be
topped up at regular intervals
The battery terminals have to cleaned and greased
regularly
TERI has been working in the area of
identifying sustainable solutions for rural areas. It has
developed many products and solutions for the masses. In
all its activities dedicated to technology innovation, TERI
consciously builds in comprehensive dimensions that are
environment-friendly, natural resource conserving, and people-oriented.
Uttam Urja Lantern
Uttam
Urja Solar Fan
Uttam Urja Domestic Lighting Systems
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