Технические науки/5. Энергетика
Zaichuk A., Chala K.
National University of Food Technologies, Kiev,
Ukraine
Solar
Electricity - Renewable Energy
Renewable
energy
is power that is generated from natural resources such as sunlight (through
photovoltaic solar cells), wind (through wind turbines), water (through dams
and hydroelectric power plants), came from renewable energy sources, In 2006,
about 18 per cent of the world's electricity consumption came from renewable
energy technologies, with 13 per cent coming from traditional biomass, such as
wood-burning. Hydroelectricity was the next largest renewable source, providing
3 per cent (15 per cent of global electricity generation, followed by solar hot
water/heating, which contributed 1.3 per cent. Modern technologies, such as
geothermal energy, wind power, solar power, and ocean energy together provided
some 0.8 per cent of total electricity generation.
Solar
electricity is created by using Photovoltaic (PV) technology by converting solar
energy power into solar electricity from sunlight. Photovoltaic solar panels
use sunlight to power ordinary electrical equipment, for example, household
appliances, computers and lighting. The photovoltaic (PV) process converts free
solar energy - the most abundant energy source on the system grid - directly
into solar power. Note that this is not the familiar "passive" or
solar installing electricity thermal technology used for space heating and hot
water production.
A PV cell consists
of two or more thin layers of semi-conducting material, most commonly silicon.
When the silicon is exposed to light, electrical charges are generated and this
can be conducted away by metal contacts as direct current (DC). The electrical
output from a single cell is small, so multiple cells are connected together
and encapsulated (usually behind glass) to form a module (sometimes referred to
as a "panel"). The PV module is the principle building block of a PV
system and any number of modules can be connected together to give the desired
electrical output.
PV equipment has no
moving parts and as a result
requires minimal maintenance. It generates solar electricity without producing emissions of greenhouse or
any other gases, and its
operation is virtually silent.
What is PV power used for?
PV systems supply solar electricity to many applications,
ranging from systems supplying power to city
buildings (which are also connected
to the normal
local solar power network) to systems supplying
power to garden lights or
to remote telecom relay stations.
The main area of interest is grid connect PV
systems. These
systems are connected to the
local solar electricity network. This means that
during the day, the home
solar electricity generated by the
PV system can either be used
immediately (which is normal for
systems installed on offices and
other commercial buildings), or can be sold
to one of
the electricity supply companies (which is more
common for domestic systems where the occupier
may be out
during the day). In the
evening, when the electrical system is unable
to provide the electricity required, power can be bought
back from the network. In effect, the grid is acting as a Solar electricity
energy storage system, which means the PV system does not need to include
battery storage.
Grid connect PV systems are often integrated into
buildings. PV technology is ideally suited
to use on
buildings, providing pollution and noise-free
solar power without using extra
space. The
use of photovoltaics on buildings has grown substantially over the last few
years, with many impressive examples already in operation.
PV systems can be incorporated into buildings in
various ways. Sloping
rooftops are an ideal site,
where modules can simply be
mounted using frames. Photovoltaic systems can also
be incorporated into the actual
building fabric, for example PV roof tiles are
now available which can be
fitted as would standard tiles. In
addition, PV can also be incorporated as building facades, canopies and sky
lights amongst many other applications.
Stand-alone photovoltaic systems have been used
for many years in the UK to supply solar electricity to applications where grid
solar power supplies are unavailable or difficult to connect to. Examples
include monitoring stations, radio repeater stations, telephone kiosks and street lighting.
There is also a substantial market for PV technology
in the leisure
industry, with battery chargers for boats and
caravans, as well as for
powering garden equipment such as solar electricity
fountains. These systems normally use batteries to
store the solar power, if
larger amounts are required they
can be combined
with another source of power
- a biomass generator, a wind turbine or
diesel generator to form a hybrid
power supply system.
PV technology is also widely used in
the developing world. The
technology is particularly suited here, where electricity
grids are unreliable or non-existent,
with remote locations often making PV power supply the most
economic option. In addition, many
developing countries have high solar
radiation levels year round.
Renewable energy electricity
production is expected to expand significantly over the coming years in the
developed world. This represents an opportunity for developed countries (large
electricity consumers) to develop and commercialize new and competitive
technologies to the traditional "fossil fuel" based technologies and
thereby manufacture products and offer services in support of a growing
industry.
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