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CPD Programme
CPD Programme
The CIBSE Journal CPD Programme programme is free and can be used by any
Members of the Chartered Institution of reader. It is organised jointly by CIBSE Journal
Building Services Engineers (CIBSE) and other and London South Bank University, and will
professional bodies are required to maintain help you to meet CIBSE’s requirement for
their professional competence throughout CPD. It will equally assist members of other
their careers. Continuing professional institutions, who should record CPD activities
development (CPD) means the systematic in accordance with their institution’s guidance.
maintenance, improvement and broadening Simply study the module and complete the
of your knowledge and skills, and is therefore questionnaire on the fi nal page, following the
a long-term commitment to enhancing your instructions for its submission. Modules will
competence. CPD is a requirement of both remain available online at www.cibsejournal.
CIBSE and the Register of the Engineering com/cpd while the information they contain
Council (UK). remains current. You can also undertake the
CIBSE Journal is pleased to offer this questionnaire online, and receive your results
module in its CPD programme. The back by return email.
Photovoltaics for buildings
The generation of electricity from photovoltaic (PV) cells has been with us for
more than 50 years, and more recent developments indicate that this form of
generation will increase rapidly in the future. Current technology emanated
from the space programme in the 1960s, and PV cells are now used in
a wide range of applications, from calculators, buildings, transport and
power stations. This CPD article will present the basic theory of the process,
investigate the costs and show applications for its use.
Photovoltaic cells Characteristics of solar power
Photovoltaics (PV) are solar cell systems that
Solar power systems generate electricity with zero emission of CO2,
convert sunlight directly into electricity. PV CLEAN
SOx, Nox or other gases associated with global warming and acid rain.
modules consist of semiconducting material
that absorbs sunlight in a way that frees RENEWABLE Solar power systems can convert nature’s sunlight into an unlimited
electrons from atoms. Electricity is produced as supply of energy.
the electrons fl ow through the semiconducting
The amount of sunlight striking earth in any given hour contains light
material. The term photovoltaic describes ABUNDANT
energy equivalent to the total world energy consumption for one year
the operating mode of a photodiode in which
electrical current through the device is entirely
due to the transduced light energy. Figure 1 diselenide (CIS) and copper indium gallium that is, a peak power of 1.5Wp (Wp signifi es
illustrates the basic operating concept. Virtually diselenide (CIGS) are being tested. Other peak power output). Typically, 36 or 72 cells,
all photovoltaic devices are some type of alternatives to silicon are being investigated, but more recently also 50 or 60 cells, are
photodiode. The three most common cell types including thin-film cadmium-telluride/ connected in series to form a ‘module’, which
used (all based on silicon) are: cadmium-sulphide, which uses even less produces a higher, more useful voltage. Cells
• Monocrystalline silicon; material than amorphous silicon cells, but are encapsulated between a transparent front
• Polycrystalline or Multicrystalline silicon; absorbs almost all sunlight. cover and a backing sheet for protection and
and hermetically sealed.
• Thin fi lm amorphous silicon. Photovoltaic modules Figure 2 shows a typical module
Other materials are used and others being A single monocrystalline PV cell (100cm
2
) construction. Conventional crystalline or
developed, For example, copper indium produces about 0.5 volts at up to 3 amps, polycrystalline silicon cells are produced >
www.cibsejournal.com January 2010 CIBSE Journal 59
CIBSEjan10 pp59-62 cpd.indd 59 18/12/09 12:52:36
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