A clear glass tube surrounds a dark tube. A vacuum exists between the dark tube and the clear glass, reducing heat transfer and energy loss. The dark tube contains a fluid that is pumped to a heat exchanger to heat water.
Parabolic trough systems are expensive. Current research lies in the following areas:Improved reflectivity of parabolic mirrorsReduced manufacturing cost of troughsSelf-cleaning (coatings)Replacing two-tank systems with one-tank thermocline systemsReducing costs of production and integration to be competitive with other energy sources
Concentrated photovoltaics focus light onto PV cells with lenses or mirrors. The PV cells used are high-efficiency and typically much more expensive than conventional PV systems. However, because the light is focused on the PV cell, a smaller cell or array can be used, keeping costs down. Concentrating photovoltaic technology offers the following advantages:Potential for solar cell efficiencies greater than 40%No moving partsNo intervening heat transfer surfaceNear-ambient temperature operationNo thermal mass; fast responseReduction in costs of cells relative to opticsScalable to a range of sizes.
Focusing solar radiation onto a stirling engine will cause it to rotate the fly wheel, and connecting it to a turbine will generate electricity.
Tracking PV heliostats move on two axes to accommodate both the tilt of the earth throughout the year as well as the rotation of the earth throughout the day. The angles are adjusted to ensure the maximum intensity of insolation is achieved.The major benefit of tracking photovoltaics is that they can generate more energy per acre than fixed-angle photovoltaics. Even though they cost more to manufacture and install, the increased amount of energy they can produce reduces the payback period.
Silicon crystal photovoltaics continue to be the primary materials used in PV systems installed today. Research at NREL and other facilities is focusing on three major areas:Thin crystalline silicon acquired via epitaxial growth. Gaseous silicon compounds are passed over a very hot substrate and the crystals that form are in a controlled orientation. Finding high efficiency and low-cost substrates for thin film applications are key.Crystallized polysilicon layersNanoscale siliconScientists at NREL are also studying new, non-crystalline materials for manufacturing photovoltaics. Organic photovoltaic (OPV) cells have an extremely broad application potential because of their flexibility, ability to absorb in different colors, and make efficient transparent devices. These properties make OPV attractive for integration into building design.
Solar Power: THE PEROVSKITE
Re s e a r c h e r :
A New Solar Material Shows
A new material described in Nature adds to the
momentum suggesting a new path to high-efficiency,
inexpensive solar cells.
By: Kevin Bullis
November 10, 2013
“The sun will be the fuel
of the future”
-Anonymous, 1876, Popular Science
Solar Power, along with
wave, biomass account
for most of the
renewable energy source
available to use.
It can be collected by
photovoltaics and heat
heat panel ).
Or solar cell, is the direct conversion of
light into electricity at the atomic level.
A photovoltaic cell (PV) is a device that
converts sun light into direct current
through photoelectric effect.
The photoelectric effect causes some
materials to absorb light photons and
convert them into electrons.
Individual PV cells are electricity-producing
devices that are made of semiconductor
The photoelectric effect is first noted by
French physicist Edmund Bequerel in 1839.
The first PV cell was constructed by Charles
Fritts in 1880.
The first major usage of PV cell is on the
Vanguard I satellite in 1958.
PV cells come in different shapes and
sizes. It can be the size of a stape, or
Depending on the level of need, the
PV cells can be put together to form a
field or a single module for residential
In general, photovoltaic modules
and arrays produce DC electricity.
Concentrating Solar Power or (CSP) is
another way of collecting energy from
Concentrating Solar Power system is
made up of lenses, mirrors, and
tracking systems focusing a large
amount of sunlight into a smaller beam.
The concentrated light heat up a
working fluid and is then used as the
heat source for power generation or
The most developed methods for
CSP are solar trough, parabolic
dish, and solar power tower.
Unlike photovoltaics, CSP can be
used at a larger scale and is more
energy efficient. Unlike PV which
converts solar ray directly into
electricity, CSP system use heat
to generate a motor in order to
A diagram of a parabolic trough solar farm (top), and an end view of how a parabolic
collector focuses sunlight onto its focal point.
Lets watch this video…
SCI 101VIDEOEnergy 101- Solar Power.FLV
Improve overall cost and cost-per-kWh
Reduce impact of materials used
Improve viability in less sunny
Solar Thermal Vacuum Tubes
Solar Thermal Troughs
Solar Stirling Engines
Tracking Solar Heliostats
Thin-film Flexible Photovoltaics
Thin c-Si via epitaxial growth
Crystallized polysilicon layers
Second-generation (“thin film”)
Less efficient, more flexible and less
expensive than 1st gen
CdTe and CIGS
Solar ink, solar dye, conductive plastic
Solar cells that use the
material “can be made
with very simple and
potentially very cheap
technology, and the
efficiency is rising very
An article in the
journal Nature describes the
materials—a modified form
of a class of compounds
called PEROVSKITES, which
have a particular crystalline
Perovskites are a plentiful
mineral that have been
interesting to material scientists
in the exploration of
conductivity, and a multitude of
dielectric properties, which are of
great importance in
PEROVSKITE is very good at
PEROVSKITE use less than one
micrometer of material to
capture the same amount of
PEROVSKITE is a
semiconductor, thus good at
transporting the electric charge
created when light hits it.
A team of physicists working at
Oxford University in the UK has
found that it's possible to use
some types of perovskite as a
replacement for thin film silicon
cells using the same basic
processing technique and still
get power efficiencies of 15
Prof Subodh Mhaisalkar (left) and Dr Nripan Mathews (right) are holding
the new Perosvkite solar cells made in NTU labs and hopes to develop into a
solar cell module, as held by Prof Sum Tze Chien (centre).
In their paper published in the
journal Nature, the researchers
report that they have discovered
that using a bubble-like
nanostructure, or an insulating
scaffold to create thin film solar
cells is unnecessary—the new
kind of cell is able to serve as a
semiconductor on its own.
FACTS IN PEROVSKITE
Organometal halide perovskites have
recently emerged as a promising material
for high-efficiency nanostructured
A simple planar heterojunction solar cell
perovskite as the absorbing layer can
have solar-to-electrical power conversion
efficiencies of over 15 percent.
Perovskite absorbers can function at the
highest efficiencies in simplified device
architectures, without the need for
Generation solar cell,
made from organicinorganic hybrid
perovskite materials, is
about five times cheaper
than current thin-film
solar cells, due to a
These perovskites tend to
have high charge-carrier
mobilities. High mobility is
important because, together
with high charge carrier
lifetimes, it means that the
and holes can move large
enough distances to be
extracted as current, instead
of losing their energy as heat
within the cell.
The team of eight researchers led by
Assistant Professor Sum Tze Chien
and Dr Nripan Mathews had worked
closely with NTU Visiting Professor
Michael Grätzel, who currently
holds the record for perovskite solar
cell efficiency of 15 per cent, and is
a co-author of the paper. Prof
Grätzel, who is based at the Swiss
Federal Institute of Technology in
Lausanne (EPFL), has won multiple
awards for his invention of dyesensitised solar cells.
The high sunlight-toelectricity efficiency of
perovskite solar cells
places it in direct
competition with thin
film solar cells which are
already in the market
and have efficiencies
close to 20 per cent.
"In our work, we utilize ultrafast lasers to
study the perovskite materials. We tracked
how fast these materials react to light in
quadrillionths of a second (roughly 100
billion times faster than a camera flash),"
said the Singaporean photophysics expert
from NTU's School of Physical and
The NTU physicist added that
this unique characteristic of
perovskite is quite remarkable
since it is made from a simple
solution method that normally
produces low quality materials.
"Now that we know exactly how
perovskite materials behave and
work, we will be able to tweak the
performance of the new solar cells
and improve its efficiency, hopefully
reaching or even exceeding the
performance of today's thin-film
solar cells," said Dr Mathews.
• "The excellent properties of
these materials, allow us to make
light weight, flexible solar cells
on plastic using cheap processes
without sacrificing the good
sunlight conversion efficiency,“
said Professor Subodh Mhaisalkar.
Researchers developing the
technology say that it could lead to
solar panels that cost just 10 to 20
cents per watt. Solar panels now
typically cost about 75 cents a watt,
and the U.S. Department of Energy
says 50 cents per watt will allow solar
power to compete with fossil fuel.
“The material is dirt cheap,” says
Michael Grätzel, who is famous within
the solar industry for inventing a type
His group has produced the most
efficient perovskite solar cells so far—
they convert 15 percent of the energy
in sunlight into electricity, far more
than other cheap-to-make solar cells.
Based on its performance so far, and
on its known light-conversion
properties, researchers say its
efficiency could easily rise as high as
20 to 25 percent, which is as good as
the record efficiencies (typically
achieved in labs) of the most common
types of solar cells today.
Perovskite solar cells
can be made by
spreading the pigment
on a sheet of glass or
metal foil, along with a
few other layers of
material that facilitate
the movement of
electrons through the
The manufacturing process
for perovskite solar cells—
which can be as simple as
spreading a liquid over a
surface or can involve vapor
deposition, another largescale manufacturing
process—is expected to be
• The researchers also showed that
it is relatively easy to modify the
material so that it efficiently
converts different wavelengths of
light into electricity. It could be
possible to form a solar cell with
different layers, each designed for
a specific part of the solar
spectrum, something that could
greatly improve efficiency
compared to conventional solar
Dr. Henry Snaith from Oxford University holding
a perovskite solar cell
When perovskites were
first tried in solar cells in
2009, efficiencies were
low—they only converted
about 3.5 percent of the
energy in sunlight into
Why do you think?
The cells also didn’t last very
long, since a liquid electrolyte
dissolved the perovskite.
But last year a couple of
to replace a liquid electrolyte
with solid materials—solved
those problems and started
researchers on a race to
Lets watch this video…
SCI 101VIDEOMaking a perovskite solar cell.FLV
“Between 2009 and 2012 there was
only one paper. Then in the end of
the summer of 2012 it all kicked
off,” Snaith says. Efficiencies quickly
doubled and then doubled again.
And the efficiency is expected to
keep growing as researchers apply
techniques that have been
demonstrated to improve the
efficiency of other solar cells.
• The perovskite material described
in Nature has properties that
could lead to solar cells that can
convert over half of the energy in
sunlight directly into electricity,
says Andrew Rappe, co-director of
Pennergy, a center for energy
innovation at the University of
Pennsylvania, and one of the new
• That’s more than twice as efficient as
conventional solar cells. Such high
efficiency would cut in half the
number of solar cells needed to
produce a given amount of power.
Besides reducing the cost of solar
panels, this would greatly reduce
installation costs, which now account
for most of the cost of a new solar
Unlike conventional solar cell materials,
the new material doesn’t require an
electric field to produce an electrical
This reduces the amount of material
needed and produces higher voltages,
which can help increase power output.
While other materials have been shown
to produce current without the aid of
an electric field, the new material is the
first to also respond well to visible light,
making it relevant for solar cells
Solar power helps to slow/stop global warming.
Solar power is a completely renewable resource.
Solar power saves society billions or trillions of
Solar power saves you money.
Solar power provides energy reliability.
Solar power provides energy security.
Solar power provides energy independence.
Solar power creates absolutely no noise at all
Solar power cannot be harnessed
during a storm, on a cloudy day or at
night. This limits how much power can
be saved for future days. Some days
you may still need to rely on oil to
power your home.