Introduction
Solar panels are also known as photovoltaic
modules.
Photovoltaic solar panels generate
electricity by converting the energy
radiated by the sun. As the name suggests
photo it means that it means "light" and voltaic
"electricity". These panels are more and more interesting because of
their effective use. Cleaner energy sources are in high demand due to the great
benefits they provide. The efficiency of these renewable energy sources is
getting better with the progress of technology and they are becoming more
common. The advantage of solar panels and solar energy over other energies is
that they can be used easily in the home.
Photovoltaic cells are made with
semiconductors. Semiconductors are elements that have a very small electrical
conductivity, but superior to that of an insulator. The most used are silicon,
this is a very abundant material, hence its low cost. When the sun's rays hit
the cells, the P-N junction of the semiconductors together with its conductive
metal helps to produce energy.
The most common panels are whose cells are
made of silicon blocks, another type of panel solar are those that left cells
are monocrystalline and polycrystalline on the right side.
There are two
disadvantages of a solar panel
1. Although silicon is very abundant, the
amount with sufficient purity (99.9999%) is limited and consequently expensive.
2._Although validated several decades ago,
silicon panels manufactured today with modern processes and finer cells need
less than two years to produce the energy that was used for their own
manufacture
On the other hand the solar panels of hot
water are the most domestic use, which uses energy from the sun in order to be
able to schedule a liquid.
These heaters count
with panels provided with a receiving
plate, next to tubes through which the liquid circulates
Types of Photovoltaic Panels
Panels (or better 'modules') photovoltaic
can be produced from many elements. With improved and new methods of
production and the use of new elements including organic materials, there is a
great variety of products today.
Solar Cells of Silicon Cells
Cells made of silicon blocks or 'ingots' are
the most common. The experience proved a useful life with frequently more
than 30 years without maintenance. Not surprisingly, most companies dare
to guarantee a yield of 80% in 25 years.
Monocrystalline panels versus
polycrystalline panels
They distinguish between solar modules made
of monocrystalline (left) and polycrystalline cells (right).
In practice the difference between the
two is minimal . Monocrystalline cell solar panels have a higher
efficiency under standard conditions (STC) which may only be relevant when
space is reduced. With polycrystalline panels, cheaper for less demanding
production, more energy can often be obtained for the same price.
At high temperatures, the loss of
efficiency in polycrystalline modules is generally less than in monocrystalline
cell panels. This has the effect that polycrystalline
panels produce more energy in conditions of high temperatures.
The loss caused by light-induced
degradation (LID) is lower in polycrystalline panels. Then over the years,
they lose slightly less efficiency (not valid for new 'p' type monocrystalline
modules, for example the Sunpower Maxeon).
For selection there are other important considerations on the performance of
crystalline solar panels.
Traditionally two arguments against solar
panels were discussed:
Silicon Shortage
Although silicon is very abundant (for
example in sand), the amount with sufficient purity (99.9999%) is limited and
consequently expensive. A shortage of high purity silicon announced
in 2005 was avoided with new discoveries and better manufacturing
processes. Several companies that invested heavily in alternative
technologies today are in serious trouble competing with traditional,
increasingly affordable silicon panels.
Energy return time
The argument that the energy needed to
produce solar panels is greater than they generate during their
lifetime. Although valid several decades ago, silicon panels manufactured
today with modern processes and thinner cells take less than two years to produce
the energy that was used for their own manufacture (see for example the data in
Mariska de Wild-Scholten ' Environmental profile of PV mass production:
globalization '(pdf) the Norwegian company Elkem manages
to recover the energy used for the manufacture of its ingots in 1.3 months
in countries with high radiation and Peru, this turnaround time is still..
shorter.
Other Solar Panels
Thin Film Solar Boards
To reduce production costs and to overcome
the possible shortage of silicon, they began to investigate and invest in
plates of other materials. In addition to thin film solar cells with silicon
(amorphous) , a significant reduction of costs was achieved using other
elements.
The most important are copper, indium and
selenium ( CIS ) or copper, indium, gallium and selenium ( CIGS )
thin layer modules and thin layer modules based on cadmium and tellurium
( CdTe ).
Modern processes such as printing
technologies result in ultra thin layers using less raw material.
massive investment in these new
technologies (largely insured by government programs) allowed installations of
solar parks large, with the result that the company First Solar (USA) with its
CdTe type plates became 2009 temporarily producer photovoltaic system in the
world.
Flexible cells
The new forms of production also allow to
produce flexible cells that open possibilities that the rigidity of the
traditional panels did not allow. These cells are increasingly incorporated
into clothing, backpacks, umbrellas, etc. Apart from special applications,
they are used to charge low consumption devices. This way you can avoid a
downloaded cell phone, power other portable devices or have light on the beach
once the sun goes down.
Panels with transparent layers
A practical development is the newly
started production of windows with semi-transparent thin layers. It is a
valid architectural alternative to include them in buildings. With these
you can replace the tinted glass and use the energy generated to support the
air conditioning of buildings.
Organic cells
Organic cells can already be woven into
clothing, for example to charge telecommunication devices. Of special
interest is the Cell Grätzel of simple
material similar to photosynthesis with very promising
characteristics. With this invention Prof. Grätzel won the Millennium
Technology Prize in 2010. They are currently preparing a first industrial
production. Because of the use of simple materials, a significant
reduction in prices is expected in the future. Contrary to crystalline
cells, they have the advantage that efficiency increases with temperature.
Concentration cells
Concentrating light with optical systems is
another development to increase the relatively low efficiency of photovoltaic
cells and reduce costs. Although efficiency has been improved by a
significant factor in installed systems, the need to orient them exactly
towards the sun and the control of the high temperature generated imposes
sophisticated systems with a high and expensive maintenance. New technologies
that avoid disadvantages are under development.
Investigations continue strongly. In
2016, for example, the Perovskite ore
was produced in the laboratory with photovoltaic cells with a surprising
efficiency of 22.1% in the laboratory. This mineral, first described in
1839, is non-toxic and known as semiconductor for years. What's exciting
is the rapid progress in achieving this efficiency in a few years (3% in 2009),
while other technologies needed decades to achieve something similar (see chart
below). This jump hopes to produce new Perovskite cells within a
few years up to 30% efficiency at very low costs .
FUNCTIONING
The operation of the solar
panels is based on the photovoltaic effect, which occurs when, on
suitably treated semiconductor materials, the solar radiation effects producing
electricity as I mentioned above.
At the time it is exposed to solar
radiation, the different contents in the light transmit their energy to
the electrons of the semiconductor materials which, then, can break the
potential barrier of the PN junction, and thus leave the semiconductor through
of an external circuit.
These photovoltaic cells combine
in many different ways to achieve both the desired voltage and power and thus
to be able to get the solar energy to be converted into energy to be consumed.
Advantage
Solar panels have a number of advantages
that make them one of the most solid future alternatives.
First, their most obvious advantage is that
they are capable of transforming the sun's rays into energy. It is,
therefore, a totally renewable and inexhaustible energy . The
energy of the sun is not in danger of disappearing, so do not worry that it
runs out, at least for many millions of years.
On the other hand, it is a way to produce
totally clean energy . Solar panels do not need chemical processes,
they do not need combustion. That is, they do not emit any kind of
pollutants into the atmosphere and do not contribute to climate change and the
greenhouse effect.
Using solar panels would end the
problem of waste storage . Fossil fuels take years to disappear,
fill to overflow the landfills and pollute the air, land and water. Not to
mention the storage of waste resulting from nuclear energy.
Solar energy would end natural disasters
such as those at nuclear power plants such as Chernobyl or Fukushima and others
that recur every so often, such as oil spills that destroy coastal and marine
ecosystems.
They contribute to self-sufficiency . The
solar panels would allow, for example, access to electricity in less favored
areas, where even the power line does not reach.
These panels can be installed on a large
scale, to produce energy in large quantities, or in the form of small home
installations, to serve as support energy. They can also serve to reduce
public spending on lighting, through solar street lamps, for example. The
possibilities are multiple.
Disadvantages
The main disadvantage of solar panels is
that solar energy is a little implemented energy and, above all,
little supported by large energy companies.
In some countries, among which Spain can
count, solar energy does not represent 0.2% of the total energy
produced. In addition, the fees and taxes on these types of
facilities are too high for a person with a middle income to risk using solar
energy.
On the other hand, among the few
disadvantages that can be mentioned is that the panels need a specific location
and position to operate at full capacity and are not as effective in areas
where there is less sun
It should also be mentioned that the installation
of solar panels or panels implies a fairly high initial outlay (solar
panels usually hover around 7,000 euros, although each is cheaper and more
efficient). However, for domestic use, it is demonstrated that these
panels can be amortized over a period of approximately 7 or 10 years at the
most.
Finally, it is true that solar panels have
an important impact on the landscape , hence they are usually located
in virtually deserted (and desert) areas, also for obvious performance
reasons. It is also true that aesthetically is not very pleasant
in a building or a cottage, but if it is in favor of energy efficiency and the
environment, it may not be such an important drawback.
Solar Panels: Importance and
Characteristics
Solar panels are modules capable of harnessing
the energy of solar radiation . This faculty includes both the solar
collectors used to produce hot water and the photovoltaic panels used to
generate electricity . In both cases, it is a clean technology that
allows energy to be obtained without compromising the environment.
The photovoltaic panels are formed by
different cells, responsible for converting light into electricity. The
cells use the technically called photovoltaic effect to transform solar energy
and get the current through two plates with opposite electric charges.
However, this type of energy has not yet
reached its technical perfection, therefore a number of firms and private
institutions are currently working with the purpose of increasing the
efficiency of the panels, in order to achieve an increase in the applications
of solar energy.
Different applications
At the same time, different developments
and investigations of universities and educational centers have allowed the
creation of solar powered vehicles and boats. One of the main drawbacks of
photovoltaic panels is the high cost involved, a feature that is however
gradually changing.
The great problem so far was the value of
silicon, used for the manufacture of the panels. At present, alternative
materials have begun to be used or to reduce the use of silicon, resulting in a
decrease in production costs. At the same time, the increase in production
will allow prices to continue to decline in the coming years.
Domestic hot water
On the other hand, solar water heaters have
a more domestic use, and they use the energy of the sun to heat a liquid, which
drives the heat into a section dedicated to storing that heat. At the
residential level, domestic hot water can be obtained and stored in a reservoir
for this purpose, satisfying the needs of a family.
These heaters also have panels with a
receiving plate, along with tubes through which circulates the liquid that
allows concrete to create heat. The receiver, which is covered with a dark
layer, is the one that transforms solar radiation into heat.
In addition, the heated liquid is pumped
into a supplement dedicated to the exchange of energy, a coil in which it is
parked to later return to the original panel, for the purpose of being
reheated. In this way, with a simple operation, clean energy is obtained
and an important contribution is provided to maintain the ecological balance on
the planet.
Conclusions
A Home Solar Heater is a system that uses the heat of the solar rays to heat water and deposit it in a thermos; it keeps it at a certain temperature until it is used for bathing or for any other domestic needs, except swimming pools.
The physical phenomenon that heats the
water is the same that makes you so hot when someone is in a car parked in the
sun with the glasses raised.
The advantages of this is that you do not
need any gas, fire and / or some other unnatural things to be able to have hot
water. It is 100% renewable energy. Reduces the use of oil by a large
percentage.
Its disadvantages
are that on cloudy days and at night the water does not heat up in its
entirety, or in a minimum. There
is a lot of competition, and therefore many poor quality jobs.
Although thin-film panels with relatively little raw material were able to reduce the cost of production, there is some uncertainty about its durability. There is still a lack of historical experience and along with some problems of production, quality leaves some doubts. While mono- and polycrystalline plates are guaranteed to produce 80% of their energy over 25 years, this life can not yet be guaranteed with the latest technologies. This directly affects the profitability of systems over time and generally favors traditional silicon boards.
