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SOLAR GENERATION V -
2008
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Photovoltaic power systems offer
many unique benefits above and beyond simple energy
delivery. That is why comparisons with conventional
electricity generation - and more particularly comparison
with the unit energy costs of conventional generation - are
not always valid. If the amenity value of the energy service
that PV provides, or other non-energy benefits, could be
appropriately priced, the overall economics of PV generation
would be dramatically improved in numerous applications,
even in some grid-connected situations. PV also offers
important social benefits in terms of job creation, energy
independence and rural development.
Space-saving installations
 PV is a simple, low-risk technology that can be installed
virtually anywhere where there is available light. This
means that there is a huge potential for the use of roofs or
façades on public, private and industrial buildings. PV
modules can be used as part of a building’s envelope,
providing protection from wind and rain or serving to shade
the interior. During their operation, such systems can also
help reduce buildings’ heating loads or assist in
ventilation through convection.
Other places where PV can be installed include the sound
barriers along communication links such as motorways. In
satisfying a significant part of the electricity needs of
the industrialised world, there will be no need to exploit
otherwise undisturbed areas.
Improving the electricity
network
For power companies and their
customers, PV has the advantage of providing relatively
quick and modular deployment. This can offset investment in
major new plant and help to strengthen the electricity
network, particularly at the end of the distribution line.
Since power is generated close to the point of use, such
distributed generators can reduce transmission losses,
improve service reliability for customers and help limit
maximum demand.
Employment
PV offers important social benefits in terms of job
creation. Significantly, much of the employment creation is
at the point of installation (installers, retailers and
service engineers), giving a boost to local economies. Based
on information provided by the industry, it has been
assumed
that 10 jobs are created per MW during production and about
33 jobs per MW during the process of installation.
Wholesaling of the systems and indirect supply (for example
in the production process) each create 3-4 jobs per MW.
Research adds another 1-2 jobs per MW. Over the coming
decades, it can be assumed that these numbers will decrease
as the use of automated machines will increase.
 This will be
especially the case for jobs involved in the production
process.
In 2006, the German PV industry alone employed 35,000
people. Such an impact on the national job market would be
impressive for any source of energy. In Germany, there are
in fact currently more jobs in the PV sector than in the
nuclear industry.
By 2030, following the Solar Generation Advanced Scenario,
it is estimated that 6.3 million full-time jobs would have
been created by the development of solar power around the
world. Over half of those would be in the installation and
marketing of systems.
Rural electrification
Solar power can be easily installed in remote and rural
areas, places that may not be targeted for grid connection
for many years. Renewable energy sources such as PV are
currently one of the few suitable options to supply
electricity in areas of dispersed communities or those at a
large distance from the grid. Decentralised (off-grid) rural
 electrification based on the installation of stand-alone
systems in rural households or the setting up of minigrids -
where PV can be combined with other renewable energy
technologies or with LPG/diesel - enables the provision of
key services such as lighting, refrigeration,
education, communication and health. This increases economic
productivity, and creates new income generation
opportunities. Furthermore, the technologies which are used
to power off-grid applications (stand-alone PV systems, PV
water pumping systems and hybrids) are often both affordable
and environmentally sound. Due to their robustness, ease of
installation and flexibility, PV systems are able to adapt
to almost any rural energy demand in any part of the world.
The load demand expected from small PV systems is usually
focused on serving household (lighting, TV/radio, small home
appliances) and social needs (health and community centres,
schools, water extraction and supply), bringing both quality
of life and economic improvements. For larger and hybrid
systems, the power supply can be extended to cover working
hours and productive loads. This could range from minor
applications such as air ventilators, refrigerators and hand
machine tools through to larger demands such us the
electrification of schools, hospitals, shops and farms.
During 2005, 86 MWp of PV solar energy was installed in
rural areas in developing countries, enabling access to
electricity for approximately 800,000 families.
Energy payback
A popular belief still persists that PV systems cannot ‘pay
back’ their energy investment within the expected lifetime
of a solar generator – about 25 years. This is because the
energy expended, especially during the production of solar
cells, is seen to outweigh the energy eventually generated.
Data from recent studies shows, however, that present-day
systems already have an energy payback time (EPBT) – the
time taken for power generation to compensate for the energy
used in production – of 1 to 3.5 years, well below their
expected lifetime. With increased cell efficiency and a
decrease in cell thickness, as well as optimised production
procedures, it is anticipated that the EPBT for
grid-connected PV will decrease further.
Figure 5.1 shows energy payback times for different solar
cell technologies (thin film, ribbon, multicrystalline and
monocrystalline) at different locations (southern and
northern Europe). The energy input into a PV system is made
up of a number of elements, including the frame, module
assembly, cell production, ingot and wafer production and
the silicon feedstock. The energy payback time for thin film
systems is already less than a year in southern Europe. PV
systems with monocrystalline modules in northern Europe, on
the other hand, will pay back their input energy within 3.5
years.
Climate protection
The most important feature of solar PV
systems is that there are no emissions of carbon dioxide -
the main gas responsible for global climate change - during
their operation. Although indirect emissions of CO2 occur at
other stages of the lifecycle, these are significantly lower
than the avoided emissions.
PV does not involve any other polluting emissions or the
type of environmental safety concerns associated with
conventional generation technologies. There is no pollution
in the form of exhaust fumes or noise. Decommissioning a
system is unproblematic.
Although there are no CO2 emissions during operation, a
small amount does result from the production stage. PV only
emits 21–65 grams CO2/kWh, however, depending on the PV
technology. The average emissions for thermal power in
Europe, on the other hand, are 900g CO2/kWh. By substituting
PV for thermal power, a saving of 835–879 g/kWh is achieved.
The benefit to be obtained from carbon dioxide reductions in
a country’s energy mix is dependent on which other
generation method, or energy use, solar power is replacing.
Where off-grid systems replace diesel generators, they will
achieve CO2 savings of about 1 kg per kilowatt-hour. Due to
their tremendous inefficiency, the replacement of a kerosene
lamp will lead to even larger savings, of up to 350 kg per
year from a single 40 Wp module, equal to 25kg CO2/kWh. For
consumer applications and remote industrial markets, on the
other hand, it is very difficult to identify exact CO2
savings per kilowatt-hour. Over the whole scenario period,
it was therefore estimated that an average of 600 g CO2
would be saved per kilowatt-hour of output from a solar
generator. This approach is rather conservative; higher CO2
savings may well be possible.
Recycling of PV modules is possible and raw materials can be
reused. As a result, the energy input associated with PV
will be further reduced.
If governments adopt a wider use of PV in their national
energy generation, solar power can therefore make a
substantial contribution towards international commitments
to reduce emissions of greenhouse gases and their
contribution to climate change.
By 2030, according to the Solar Generation Advanced
Scenario, solar PV would have reduced annual global CO2
emissions by just over 1 billion tonnes. This reduction is
equivalent to the 2004 emissions from the whole of India, or
the output from 300 coal-fired power plants (average size
750 MW). Cumulative CO2 savings from solar electricity
generation between 2005 and 2030 will have reached a level
of 6.6 billion tonnes.
Carbon dioxide is responsible for more than 50% of the
man-made greenhouse effect, making it the most important
contributor to climate change. It is produced
mainly by the burning of fossil fuels. Natural gas is the
most environmentally sound of the fossil fuels, because it
produces roughly half as much carbon dioxide as coal, and
less of other polluting gases. Nuclear power produces very
little CO2, but has other major safety, security,
proliferation and pollution problems associated with its
operation and waste products. The consequences of climate
change are already apparent today (see panel ‘Scientific
Assessment of Climate Change’).
Security of supply
The EPIA/Greenpeace Advanced Scenario shows that by 2030, PV
systems could be generating approximately 1,800 TWh of
electricity around the world. This means that enough solar
power would be produced globally to supply more than half of
the current EU electricity needs, or replace 300 coal-fired
power plants (average size 750 MW).
Global installed capacity of solar power systems could reach
1,300 GWp by 2030. About two-thirds of this would be in the
grid-connected market, mainly in industrialised countries.
Assuming that their average consumption per 2.5 person
household is 3,800 kWh, the total number of people by then
generating their electricity from a grid-connected solar
system would reach 776 billion. Although the key markets are
currently located mainly in the industrialised world, a
global shift will result in a significant share being taken
by the now developing world in 2030. Since system sizes are
much smaller than grid-connected systems, and the population
density greater, this means that up to 2.9 billion people in
developing countries would by then be using solar
electricity. This would represent a considerable
breakthrough for the technology from its present emerging
status.
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