2. (1) A lighting system composed of an LED lamp, solar
panels, battery, charge controller and there may also be
an inverter
(2) The lamp operates on electricity from batteries, charged
through the use of solar photovoltaic panel
(3) Solar lamps use renewable energy with infinity supply
which is cheaper than standard lamps
(4) Solar lamps reduce health risk as kerosene lamps have a
bad impact on human health
(5) Solar lamps in rural areas have the capability of
providing a supply of electricity for other devices, such
as for charging cell phones
3. In the past solar panels used large crystals mainly made out of
silicon which produced electricity when it was exposed to light
Physics Behind:
[
When electrons in silicon are exposed to light, they start to vibrate
from their fixed positions following thermodynamics rules.
Furthermore, it produces heat from the vibration and the
movement. Through this, silicon turns a large portion of light
energy into electricity. However, manufactures found silicon too
expensive to make and to put in as a component of solar lamps. ]
Photoelectric effect used in solar cells was first noted by Edmond
Becquerel, a French physicist, in 1839. Albert Einstein won a
Nobel prize in 1922 by exploring the nature of light and the
photovoltaic technology based on photoelectric effect. The first
photovoltaic module was built in 1954 by Bell Laboratories
4. (1) Solar panels are made out of crystals that are
made out of covalent bonds between electrons
on the outer shell of silicon atoms
(2) Silicon is a semiconductor which is neither
metals that conducts electricity nor insulators
that do not conduct electricity. Semiconductors
normally do not conduct electricity but under
certain circumstances they do in this example
with exposition to light
(3) A solar cell has two different layers of silicon.
The lower layer has fewer electrons and hence
has a slight positive charge due to the negative
charge nature of electrons
5. (4) In addition, the upper layer has more electrons
and has slightly negative charge. A barrier is
created between these two layers . However, when
the stream of light particles called photons enter,
they give up their energy to the atoms in the
silicon. It promotes one electron from a covalent
bond to a next energy level from upper layer to
the lower layer
(5) This process called photovoltaic system literally
means combination of light and voltage and they
use photovoltaic cells to directly convert sunlight
into electricity
6. (6) Solar panels are made out of layers of different
materials (Figure), in order of glass, encapsulate,
crystalline cells, encapsulate, back sheet,
junction box and lastly frame. The encapsulate
keeps out moisture and contaminants which
could cause problems
7. The battery is housed within a metal or plastic case.
Inside the case are electrodes including cathodes and
anodes where chemical reactions occur. A separator
also exists between cathode and anode to stop the
electrodes reacting together.. Batteries inside solar
lamps usually use gel electrolyte technology with high
performance in deep discharging, in order to enable
use in extreme ranges of temperature. It may also use
lead-acid, nickel metal hydride, nickel cadmium, or
lithium. In general, the efficiency of photovoltaic
energy conversion is limited for physical reasons.
Around 24% of solar radiation of a long wavelength is
not absorbed. 33% is heat lost to surroundings, and
further losses are of approximately 15-20%. Only
23% is absorbed which means a battery is a crucial
part of solar lamp
8. This section controls the entire working systems to protect
battery charge. It ensures, under any circumstances
including extreme weather conditions with large
temperature difference, the battery does not overcharge or
over discharge and damages the battery even further.
LED lights are used due to their high luminous efficiency
and long life. Under the control of a DC charge controller,
non-contact control automatically turns on the light at
dark and switches off at daytime. As shown in Figure the
chip includes microchip (R), B-, B+, S- and S+. S+ and S-
are both connected to solar panels with wire, one of which
has plus charge and the other minus charge. B- and B+ are
attached to two batteries in this case. The light will be
shown through the LED light when all of these are
connected
9. (1) Solar lamps can be easier to install and maintain as they do not
require an electricity cable
(2) Solar lamps can benefit owners with reduced maintenance cost and
costs of electricity bills
(3) Solar lamps can also be used in areas where there is no electrical grid
or remote areas that lack a reliable electricity supply
(4) There are many stories of people with lung disease, eye deterioration,
burns and sometimes even death simply because they do not have a
healthy alternative to light at night
(5) Women have felt unsafe walking to the toilet outside after dark.
Babies are being delivered by midwives using only a candle, and
students cannot study when the sun goes down for lack of light
leading to increased illiteracy and perpetual poverty
10. (6) Households switching to solar lamps from kerosene lamps
also gain from health risk associated with kerosene emissions.
Kerosene often has negative impacts on human lungs
(7) The use of solar energy minimizes the creation pollution
indoors, where kerosene have been linked to cases of health
issues
(8) The use of solar lights improves education for students who live
in households without electricity
(9) When the nonprofit Unite-To-Light donated solar-lamps to
schools a remote region (of Kwa Zulu Natal) in South Africa
test scores and pass rates improved by over 30%. The light
gives students added time to study after dark
11. In rural India, solar lamps, commonly called solar
lanterns, using LEDs can replace candles and kerosene
lamps. Especially in areas where electricity is otherwise
difficult to access, solar lamps are ideal substitutes to
conventional lanterns.
Sunlight is free to our world. So why not use it up to it’s
maximum potential for the betterment of the needy and
bring smiles to their pale faces.
12. Developing an LED Lamp,
driven by renewable energy sources
(in this case, Solar) for Rural Education
13. (1) Stable illumination for almost whole night usage
(2) High durability and ample efficiency
(3) Cost effectiveness & commercial viability
14. (1) Introducing auto cut-off techniques in presence of considerable
ambient light (acceptable light intensity can be adjusted)
(2) Continuous adjustment of LED intensity while monitoring battery
status to maximize system lifespan
(3) Using low powered MCU to coordinate between previously mentioned
smart power saving feature as well as using proximity sensor to detect
presence of a user and to auto turn OFF / ON the system based on user
activity / presence
15. It is an ongoing project to find a low cost,
efficient substitute material that can patently be
mass-produced and will be convenient in
conversion of light into electricity
