Up Gradation of Facilities to Produce Silicon
Solar Modules Up To 80kw Annual Capacity
Approved in DDWP meeting
Pakistan Council of Renewable Energy
Government of Pakistan
1. Name of the Project: Up gradation of facilities to produce Silicon
Solar Modules up to 80kW annual capacity
2. Location: Pakistan Council of Renewable Energy
25 H-9, Islamabad
3. Authorities responsible for:
i) Sponsoring: Ministry of Science & Technology
Government of Pakistan
ii) Execution: Pakistan Council of Renewable Energy
iii) Operation & Maintenance: Pakistan Council of Renewable Energy
iv) Concerned Federal Ministry: Ministry of Science & Technology
4. Plan provision: Out of block allocation of MoST/MTDF for the
development and promotion of renewable
5. Project Objectives and its relationship with Sectoral Objectives:
a) Project Objectives
Up gradation of silicon crystal growing and wafering facilities.
To enhance the indigenous production of solar cells/ modules up to
80 kW per annum.
Promotion of clean and renewable source of energy.
b) Relationship with Sectoral Objectives:
Pakistan Council of Renewable Energy Technologies (PCRET) has been established
to research, develop, and promote Renewable Energy Technologies (RET) in the
country. The council has developed processes of growing silicon crystals, wafering,
fabrication of silicon solar cells and modules. This project aims to use these skills and
start limited production of solar cells and modules to the tune of 80kW/ annum.
Implementation of this project will boost up the industrial and economic activities
relating to solar energy technologies in Pakistan.
6. Description, Justification and Technical Parameters
A brief History of Photovoltaics (P.V)
Photovoltaic is a clean and environment friendly technology that converts the sun
energy directly into electric power via device called PV modules. A first silicon
module of 2% efficiency, was designed for out door use by Bell Laboratories in 1955
in USA. Whereas the first commercial use of the PV modules was to power the
telecommunication system of the satellites. This market remained dominated for 20
years. On terrestrial side the technology was first time used on commercial basis when
256 light houses along the Japan coastline were provided power from 1961-1972,
using PV modules based on the Bell solar cell technology. In 1972 the price of the PV
was US$ 50 per watt.
It is only in the 1970s that with the oil crises, the development and use of PV modules
for terrestrial application was thought seriously. As a result of intensive research and
development, the price dropped to US $ 20 to 30 per watt with module efficiency of
4.6 to 4.8% in 1975. As a landmark in 1976 an 11 watt modules of 6.4% efficiency
was introduced. Heavy investment in R&D not only improved the efficiency and
performance of modules but also brought down its over all cost. In 1979 efficiency
reached to 8.4% with a price of US$ 12-18 per watt. The current state of art crystalline
silicon wafer technology is providing 9 -16% efficient modules in the market at the
cost of US $ 6-9 per watt.
Other than crystalline silicon, during last fifty years a large variety of semiconductor
materials have been used to develop the solar cell and modules. But no real
commercial break through has been made so far. Even to-day crystalline silicon wafer
technology is dominating the market. More than 88% of the global annual shipment of
PV modules consists on silicon wafer technology (Fig.1). The trend and future
forecast by the experts, show that technology will continue to dominate at least up to
The Market Trend
During last five years, the PV sector has seen the growth rate of 30% to 40% per
year that is after wind, the second highest growth rate in the energy sector. The
majority of this growth has come from five main markets i.e. Japan, Germany, USA,
China, and India. This is mainly because of the policy and subsidies provided by the
respective governments. Japan market has shown remarkable growth that is still
continuing to grow even though Japan government has reduce its direct subsidy from
50% of the cost to 10%. In fact PV has become a status symbol in Japan. The
installation shows that the owner has the money to afford and cares for the
The German market has boomed in the last 5 years having 400 MW installed during
2004. The European Union is playing quite a role and has declared that they will
achieve target to have 50% renewables of total annual energy supplies by 2040. In
USA the market is dominated by California where almost 85% of the grid connected
installations were made in 2003. in the rest of the USA the new markets are appearing
in New Jersey and Illinois because of their subsidy programme. The China market has
also grown very fast because of their Township Electrification and Remote Areas
Electrification programmes. China is committed to 400 MW of PV by 2010. This
figure will rise to 1 GW by 2020. India is installing at the rate of 20MW per year and
targeting to have 600 to 700 MW by 2010. The basic market of the PV is grid
connected and off grid rural electrification and is growing quite fast.
There is now realization in Pakistan about the importance of the use of PV for
providing electric power to the people living in far flung areas to improve their socio
economic conditions. Energy security and supply is on the top agenda of the
government who has committed to provide electric power to every one in the rural
area. It is expected that out of more than 50,000 un-electrified villages, at least 500
will be initially electrified through P.V.
Pakistan Council of Renewable Energy Technologies (PCRET) has been established
under Ministry of Science & Technology to research, development and promote the
renewable energy technologies including photovoltaic. The Council has developed the
know how and technologies in the field of silicon wafers, solar cells fabrication, and
modules fabrication technologies and now has quite experience in designing,
developing, installation, training the end users, and maintenance of the PV systems.
PCRET has already taken some projects to electrify villages, schools, and mosques
using PV and more comprehensive programme have been submitted under MTDF for
the pursuance of the government.
Facility up gradation
The laboratories of the council are equipped with facilities for producing silicon
wafers, solar cells, and modules at R&D level. However, the equipment is now 25
years old and has passed its life. This is a time to upgrade the facilities to use the
developed know how to produce the silicon wafers, cells, and modules to meet some
of the demands in the fields of PV. This project has been designed to upgrade the
facilities to produce 80 KW photovoltaic modules per year. The main equipment to be
added is silicon crystal grower and Dicing machine to produce single crystal silicon
7. Capital Cost Estimates
a) Date of estimation of project cost
b) Basis of cost estimation
Local market, Internet prices, etc.
(c)Cost of Project
Component-wise, Year-wise Physical Activities
Year-I Year-II Total
Item Total Local FEC Total Local FEC Total Local FEC
Pay and allowances 6.348 6.348 ------ 8.508 ----- 14.856 ------
Equipment/Accessories/Sp 117.000 8.000 109.000 10.000 6.000 133.000 13.000 120.000
are parts (AnnexII)
Raw Materials/Supplies 18.000 6.000 12.000 3.540 3.540 25.080 9.540 15.540
Civil work/partition in 0.250 0.250 ----- 0.050 ----- 0.300 0.300 -----
Telephone, Fax, E-mail & 0.100 0.100 ----- 0.100 ----- 0.200 0.200 -----
Books/Journals 0.300 0.150 0.150 0.200 0.100 0.100 0.500 0.250 0.250
TA/DA 0.100 0.100 ---- 0.100 0.100 ----- 0.200 0.200 -----
Purchase of 2.000 2.000 ----- ------ ------ 2.000 2.000 ------
POL/ Repair & 0.100 0.100 ----- 0.250 ------ 0.350 0.350 -----
Foreign 1.500 0.500 1.000 0.200 0.300 2.000 0.700 1.300
Honorariums 0.200 0.200 ---- 0.300 0.300 ------ 0.500 0.500 -----
Utility 1.000 1.000 ---- 1.000 1.000 ------ 2.000 2.000 ------
Contingencies 1.500 1.500 ----- 1.500 1.500 ------ 3.000 3.000 -----
148.398 26.248 122.150 35.588 25.648 9.940 183.986 46.896 137.090
8. Annual Operating Cost after completion of the Project
S. Description F.E.C Local Total
No. (Rs. in (Rs. in (Rs. in
Million) Million) Million)
1. Pay and Allowances (Annex-IV) - 9.468 9.468
2 Spare Parts + Accessories 12.000 1.000 13.000
3 Silicon 8.000 - 8.000
4 Crucibles 1.000 - 1.000
5 Laminating Materials 1.200 - 1.200
6 Tampered Glass - 1.600 1.600
7 Aluminum Frames - 2.000 2.000
8 Chemicals/Materials 2.000 8.000 10.000
9 POL/Repair & Maintenance - 0.300 0.300
10 Books/Journals - 0.250 0.250
11 Conference/Training etc. 0.750 0.750 1.500
12 Utilities - 1.000 1.000
13 Contingencies - 0.250 0.250
Total 24.950 24.618 49.568
Source of Financing : Federal Government through Ministry of Science and
9. Demand Supply analysis (excluding Science & technology, research, governance
and Culture, Sports & Tourism Sectors)
10. Financial Plan & Mode of Financing.
Federal Government through Ministry of Science & Technology
11. (a) Project Benefits and Analysis
The project will produce indigenously, the silicon solar cells and modules to
cater the fast growing market needs in the country and hence to safe the foreign
exchange in importing the PV modules for the purpose of rural electrification.
The project will earn annual profit of about 4 million rupees (Annexure-V).
PV modules so produced will be used to electrify the remote areas that are
deprived of the basic necessities of life. The activity will greatly improve their
quality of life through improvement of health and poverty alleviation.
Environmental Impact Assessment, Negative/Positive:
No environment threat is involved. In fact the project is meant to promote clean
energy technology. Utilization of its product will save additional 43 tones of CO
2 in first year from going in to the atmosphere.
Annual Production : 80 KW
Annual Power Generated : 173 MWh
Power generated in Ten year : 9.5 Gwh
Equivalent K.S. Oil saved in 10 years: 990 Tones
Reduction in CO2 Emission in Ten years: 2365 Tones
(b) Project Analysis
Direct: About 50 scientists, technicians, skilled and semi-skilled
People will be employed in the project.
Indirect: More than 500 people / year for next ten years will get indirect
employment due to the activities generated in the field of rural
End Users: Most of the products will be used by
i) PCRET for its demonstration and electrification of remote
area projects and
ii) other agencies such as AEDB for their rural areas
Impact of delays on Project cost and viability
PV being the future energy technology, the multinational companies in the
business of PV has already started stocking the silicon material that is now
disappearing from the market. The un-availability of high purity silicon could
adversely effect the production. This can be solved by establishing small scale
production unit of high purity silicon in PCRET. The raw material i.e. quartz and
silicon sand are available in Pakistan.
12. Implementation of the Project
Indicate starting and completion date of the project
Starting date : July, 2006
Completion date : June, 2008
(If every thing goes smooth)
Item – wise/year-wise implementation schedule in line chart co related with
the phasing of physical activities.
1st Quarter : 1. Appointment of the officers and staff.
2. Selection of the equipment
3. Selection of raw materials/supplies.
4. Selection of Books.
5. Purchase of vehicles.
2nd Quarter 1. Ordering of the equipment.
2. Ordering of raw materials/supplies.
3. Starting of civil work.
4. Local training of staff.
3rd Quarter : 1. Receiving and commissioning of local equipment.
4th Quarter : 1. Commissioning & testing of local equipments.
2. Receiving of raw materials/supplies.
3. Foreign trainings of equipments
Ist Quarter 1. Initiating the production, with in existing facilities.
2. Foreign trainings of equipments.
2nd Quarter : 1. Receiving & Commissioning of foreign equipments.
2. Training of staff..
3rd Quarter : 1. Production of solar cells/panels.
4th Quarter : 1. Production of solar cells/panels.
2. Project Evaluation/Reports .
13. Management Structure and Manpower Requirements
Manpower Requirements during execution and operation of Project Skill-wise
S.No. Post (Designation) Total Existing Additional
1. Project Director 1 - 1
2. Deputy Director 2 1 1
3. Assistant Director 5 1 4
4. Principal Technician 4 - 4
5. Senior Tech. Asst. 8 2 6
6. Tech. Assistant 10 5 5
7. Lab. Attendant 23 3 20
8. Superintendent 1 - 1
9. Assistant (Accounts) 1 - 1
10. Store Supervisor 1 - 1
11. Steno typist 1 - 1
12. Driver 1 - 1
13. Naib Qasid 1 - 1
Total 59 12 47
Lab. Wise Requirement
LABORATORY P.D D.D A.D P.Tech S.T.A. T.A. L.A.
(B- 19) (B-18) (B-17) (B-16) (B-14) (B-11) (B-3)
Crystal Growth 1 1 1 1 2 2 4
Wafering 1 1 2 2
Lamination 1 1 2 2 6
Cell Process 1 1 2 2 3 10
Testing 1 1 1 1
TOTAL 1 2 5 4 8 10 23
S.No. Post (Designation) BPS No. of Posts
1. Superintendent Admn/Accounts 16 1
2. Assistant (Accounts) 11 1
3. Store Supervisor (Procurement) 14 1
4. Stenotypist 12 1
5. Driver 4 1
6. Naib Qasid 1 1
Job Description, Qualification, Experience, Age & Salary of each
S/N Name of Posts Job Description Subject Qualification / Experience Age Max. Salary/
(Years) Rs (P.M)
1. Project Director Physical and financial planning, implementation Science: Physics/Material Ph. D. with 7 years or M. Phil/MSc 45 55,000
to get the goals as per PC-I Sciences/Electronics/ Engg. With 10 years or M.Sc./B.E.
Photovoltaics. with 12 years experience
Engg: Micro Electronics
2. Senior Research Officer/ Responsible to install/commission the equipment Science: Physics/Material Ph.D. or 35 45,000
Deputy Director and develop/maintain the process in his lab. Sciences/Electronics/ M. Phil/M.Sc Engg with 4 years or
Photovoltaics. M.Sc. with 4/5 years experience
Engg: Micro Electronics
3. Research Officer/ Support DD to commission/ install equipment & Science: Physics/Material MSc./B.E. 30 35,000
Assistant Director machinery & establish processes. Sciences/Electronics/ (One Second Div. Admissible in
Photovoltaics., Academic Career, No third Div.
Engg: Micro Electronics Admissible)
4. Principal Technician Operate, maintain the equipment and supervise Electronics, Electrical, 3 years Diploma (DAE) or B.Sc. 35 25,000
the processes. Mechanical, Refrigeration. (Physics, Chemistry) with 8 years
5. Senior Technician. Process wafers/cells/modules Electronics, Electrical, 3 years Diploma (DAE) or B.Sc. 30 21,000
Mechanical, Refrigeration. (Physics, Chemistry) with 3 years
6. Technician Responsible to run the concerned Electronics, Electrical, 3 years Diploma (DAE) or B.Sc. 25 14,000
equipments/processes Mechanical, Refrigeration. (Physics, Chemistry)
7. Lab. Attendant Process the technique Science Matric 25 8,000
8. Superintendent Admin / Responsible for the administrative & financial B.com 12 years 45 25,000
Account matters in relevant field
9. Assistant (Accounts) To work on routine accounts branch work B.com 05 years 35 21,000
in relevant field
10. Store Supervisor Responsible for procurements of stores B.A. 05 years 35 21,000
(Procurement) in relevant field
11. Steno- typist Support staff F.A. with Shorthand with 80 5 years 30 17,000
Typing 40 wpm
12. Driver Support staff Matric with LTV/HTV driving 5 years 35 9,000
13. Naib Qasid Support staff Matric 02 years, similar experience 25 7,000
14. Additional Projects/Decisions required to maximum
Benefits from the proposed Project
15. Certified that the Project proposal has been prepared on
the basis of instructions provided by the Planning Commission
for the preparation of PC-I for Social Sector Projects
Salary of Additional staff (Capital cost)
S. Name of Post Consolidated/ No. of Months For 2 years
No P.M. Post (Million Rs.)
1. Project Director 55,000 1 24 1.320
2. Deputy Director 45,000 1 24 1.080
3. Assistant Director 35,000 4 24 3.360
4. Principal Technician 25,000 4 24 2.400
5. Senior Tech. Asst. 21,000 6 24 3.024
6. Tech. Assistant 14,000 5 12 0.840
7. Lab. Attendant 8,000 20 06 0.960
8. Superintendent Admn/Account 25,000 1 24 0.600
9. Assistant (Accounts) 14,000 1 24 0.336
10. Store Supervisor (Procurement) 21,000 1 12 0.252
11. Steno typist 17,000 1 24 0.408
12. Driver 9,000 1 12 0.108
13. Naib Qasid 7,000 1 24 0.168
Total 50 14.856
DETAIL OF EQUIPMENT COST
S. No. Description Rs. Million
1. Crystal Growing Furnace 65.00
(Charge: 20 Kg (min), Ingot Diameter: 6 inches (min.))
2. Wafering Saw 25.00
(Type: Wire Cutting, Supply: 220/240V, 50 Hz,
Feed rate: 0.1-2.0mm/Sec. Accuracy: 5 microns)
3. Grinding Machine 1.00
(Power : 220/240 V, 50 Hz, Wheel : five grain Diamond Coated)
4. D I Water Plant 2.00
(with Sand filter, Softener, Deionizer)
(output: 10 gpm, resistively : 20 Mohm)
5. Diffusion Furnace 19.00
(Type: Conveyer, Speed (IPM) : 2-40, Belt Size (Inches): 10
Operating Temp: 350 – 1000 C
6. Laminators 0.80
(Panel Size : 150 x 80 mm, vacuum: 1mmHg)
7. Cell Testing Equipment 3.00
(Cell Size : upto 15cm X 15cm,
Voltage/Current Ranges: 0-10V; 0-10Amp)
8. Lab. Accessories 5.00
9. Spare Parts 5.00
10. Diesel Generator 3.00
(50Hz, 3 Phase, 380V, 300Kw)
11. Cooling Tower 1.20
(Capacity: 60 gpm (min); temp. from 50 oC to 20 oC )
12. UPS 2.00
(3 Phase, 50Hz, 380V; 200KW; Time: 15 minutes)
S.No. Description Rs. Million
Hyper Pure Silicon 8.00
Quartz Crucibles 1.00
Laminating Materials 2.40
Tempered Glass 1.60
Aluminum Frames 2.08
Chemicals / Materials 10.00
Salary & Allowances – Recurring Cost
S.No Designation BPS
Rate (Mill Rs.)
1. Project Director 19 1 55,000 0.660
2. Deputy Director 18 1 45,000 0.540
3. Assistant Director 17 4 35,000 1.680
4. Principal Technician 16 4 25,000 1.200
5. Senior Tech. Asst. 14 6 21,000 1.512
6. Tech. Assistant 11 5 14,000 0.840
7. Lab. Attendant 3 20 8,000 1.920
8. Superintendent 16 1 25,000 0.300
9. Assistant (Accounts) 11 1 14,000 0.168
10. Store Supervisor 14 1 21,000 0.252
11. Steno typist 12 1 17,000 0.204
12. Driver 4 1 9,000 0.108
13 Naib Qasid 1 1 7,000 0.084
Total 47 9.468
Silicon Material : 130
Wafer Production : 55
Cell Fabrication : 85
Module Fabrication : 80
Total : 350
Selling Price : 400
Annual Profit : 4.0 million Rs.
The Energy Intensity of Photovoltaic Systems
Andrew Blakers and Klaus Weber
Centre for Sustainable Energy Systems
Engineering Department, Australian National University
The use of photovoltaic systems on a large scale in order to reduce fossil fuel consumption and
greenhouse gas emissions requires that the energy associated with the construction, operation and
decommissioning of PV systems be small compared with energy production during the system
lifetime. That is, the energy payback time should be short. The energy intensity and cost of PV
systems are closely related. At present the energy payback time for PV systems is in the range 8 to
11 years, compared with typical system lifetimes of around 30 years. About 60% of the embodied
energy is due to the silicon wafers. As the PV industry reduces production costs and moves to the
use of thin film solar cells the energy payback time will decline to about two years.
The use of photovoltaic systems on a large scale in order to reduce fossil fuel consumption and
greenhouse gas emissions requires that the energy associated with the construction, operation and
decommissioning of PV systems be small compared with energy production during the system
lifetime. That is, the energy payback time should be short compared with the system lifetime.
A distinction needs to be drawn between energy consumption and carbon dioxide production
associated with PV systems. Although there appears to be relatively limited reserves of oil and gas,
coal is abundant. The most likely cause of a cessation of coal burning is not depletion of supplies,
but rather unacceptable climatic consequences. In addition to energy payback time for PV systems,
carbon dioxide payback times need to be considered. Both times must be short compared with the
PV system lifetime if a large sustainable PV industry is to the established. In general, energy
intensity and carbon dioxide intensity are closely related. Over the next few decades at least the
energy used to construct PV systems will be derived primarily from fossil fuels. In the long term
"solar breeding" will be possible, whereby energy for the production of PV systems will be derived
from PV systems. This will reduce or eliminate carbon dioxide emissions associated with PV system
By far the largest fossil fuel inputs for a photovoltaic system are associated with production and
installation. Fossil fuel derived energy required for the operation and decommissioning of a PV
system is trivial. Hydroelectricity and wind energy share this characteristic. Many studies have
looked at energy inputs to PV systems. It is difficult to arrive at definitive numbers because
production technology is constantly improving and because the fossil fuel intensity of various
operations depends on production scale and production location.
An important conclusion can be drawn from the various studies. The cost of the various components
of a PV system is well correlated with the energy content of that component. The reason for this is
that PV is a material intensive technology, and the energy content of materials is reflected in their
price. Thus the most expensive component of a conventional PV system, the silicon wafers, is also
the most energy intensive component. It is clear that as the cost of PV systems declines, then so will
the energy content.
Most PV systems are based on panels that comprise about 40 single or multicrystalline silicon
wafers encapsulated behind glass using an EVA pottant material. An aluminium frame and a
junction box complete the panel. Groups of panels are connected together on supporting structures
that are mounted on buildings or in open fields. The cost of the silicon wafers amounts to about half
of the cost of a PV panel. It is likely that thin film solar cells based on thin layers of crystalline
silicon or alternative materials (amorphous silicon, copper indium diselenide, cadmium telluride)
will challenge wafer based crystal silicon solar cells over the next decade. The result will be a
substantial reduction in the energy and carbon dioxide intensity of PV systems.
This study focuses on crystalline silicon PV panels. At present, crystalline silicon wafer panels have
85-90% of the world market. There is a high likelihood that the dominance of crystal silicon solar
cells will continue for many years to come because of the abundance and non-toxicity of silicon, the
high and stable efficiency of silicon solar cells, the ability to share R&D, infrastructure and human
resources with the IC industry and its present market acceptance and dominance. Although solar
cells based on silicon wafers are likely to eventually be replaced over the next decade by thin film
solar cells, there is every chance that the thin film solar cells will in fact be fabricated from thin films
of crystalline silicon rather than from other materials.
The main goal of the Epilift [Description 1997] project is to create efficient solar cells using thin
crystalline silicon cells that use 10% of the amount of silicon used in conventional wafer-based
silicon solar cells. The energy content of the crystal silicon in an Epilift PV panel will be greatly
reduced. Amorphous silicon panels and Epilift panels will have similar embodied energy per square
metre. [Press release 1997, Third Generation 2000]
The various studies of the embodied energy of currently produced PV systems that have been
performed over the years make a range of different assumptions. Their results range over a factor of
two for the energy payback time of a PV system. However, the predictions for the energy payback
time of future PV systems are all small (a few years). This is because the availability of PV systems
with a sufficiently low cost to be deployed in large quantities will require the elimination of
expensive components, which also tend to be the energy intensive components (e.g. silicon wafers,
aluminium frames and expensive support structures).
In this study, estimates at the high end of embodied energy in PV systems have been adopted.
However, the likely future elimination of the energy intensive components of PV systems means that
most future estimates converge at rather small numbers for embodied energy.
In addition to energy embodied in PV materials, the energy embodied in the machines used in
manufacturing need to be taken into account. Similarly, the energy used to manufacture the
machines that are used to manufacture the production machinery needs to be taken into account, and
so on. However, in an energy intensive product such as a PV panel the energy embodied in the
materials far exceeds the energy embodied in the production machinery, and the latter can be
neglected for practical purposes. Indirect energy, such as for heating, lighting, office equipment and
transport is a significant overhead and must be included.
Electricity is related to primary energy (usually fossil fuels) through the average electrical energy
conversion efficiency of the electricity industry, which is assumed to be 38%. Since the output of a
PV panel as well as most of the energy inputs are in the form of electricity, electricity (in kilowatt
hours, kWh) has been used as the basic energy unit in this study. Megajoules and kilowatt-hours are
related by 1 kWh = 3.6 MJ.
The lifetime of a PV system is assumed to the 30 years. Many manufacturers now offer 20-year
guarantees, and PV panels might last 40 to 50 years in non-maritime locations.
The energy output to of a PV panel depends on its location. In this study the location is assumed to
be Sydney. The PV panels are assumed to be mounted on a fixed frame facing north and tilted at the
latitude angle. The average irradiation on the panels is 6,935 MJ per square metre per year (1,926
kWh/m2/year) . In Port Hedland in NW Australia, which is an excellent site by world standards,
the average irradiation on the panels is 2,494 kWh/m2/year. Sydney has good insolation compared
with most places in Europe (30-70% larger).
The actual electrical output of the PV system is the irradiation multiplied by the system efficiency.
The single crystalline silicon solar cells are assumed to have an efficiency of 14% under standard
testing conditions. The cell efficiency (after encapsulation) during actual operation (elevated
temperature, reduced insolation intensity, dirty glass etc) is reduced to 11%. The panel will have an
output of 100 W/m2 under 1 kW/m2 illumination (allowing for a cell packing factor of 91%). In
Sydney the annual average energy production of a panel will be 193 kWh/m2/year before system
Electrical losses caused by the inverter, transformer and electrical resistance are assumed to be 15%.
Electrical losses in the State distribution network are assumed to be 7%. The overall electrical
efficiency of the balance of systems (BOS) components is thus 79%. This reduces the annual
average energy production of a panel to 153 kWh/m2/year.
Production and installation of a PV system can be divided into three sectors:
Production of the silicon wafer;
Fabrication and packaging of the solar cells to create a PV panel
Installation of many panels to form a PV system
Production of silicon wafers
Silicon wafers are produced from electronic grade silicon (EG-Si), which in turn is produced from
metallurgical grade silicon (MG-Si). Metallurgical grade silicon is used in large quantities in the
steel and other industries. It is created by the carbothermic reduction of silicon dioxide (quartz,
sand), a process in which coal, coke and woodchips are heated together with silicon dioxide. The
carbon strips the oxygen from the silicon dioxide to create carbon dioxide and silicon. This process
produces carbon dioxide both directly as part of the chemical reaction and indirectly since the
reactor must be heated electrically. The energy content of the carbon could have been used to
produce electricity. This forgone energy production is included in these calculations.
Metallurgical grade silicon has a typical purity of about 98%. This must be upgraded to around
99.9999999% in order to meet the requirements for the semiconductor industry. The purification
process is generally accomplished via the Siemens process. Silicon is reacted with HCl to produce
trichlorosilane, which is then the decomposed with the aid of hydrogen at 1200 degrees to produce
highly pure electronic grade polycrystalline silicon (EG-Si) and silicon tetrachloride (SiCl4). There
is 3.5 kg of silicon embodied in the SiCl4 for each kg of EG-Si produced. The SiCl4 is used to
produce pigment, quartz fibre etc. The energy content of the SiCl4 is ascribed to these other
industries rather than to the solar cell industry. The yield of the purification step is assumed to be
The next step is to melt the EG-Si in a Czochralski crystal puller at 1400 degrees and slowly
crystallise the silicon to form a single crystal ingot of silicon. Alternatively, the EG-Si can be melted
and crystallised by the casting process to make a large grained multicrystalline silicon ingot. It is
assumed that only 80% of the EG-Si loaded into the Czochralski crystal puller is used, with the
losses mostly due to the removal of the top and tail of the ingot (which has a lower purity). The yield
of the Czochralski process itself is assumed to be 90%, giving a total yield of 72%.
The final step in wafer production is to slice the ingot into wafers. This is done with a multiwire saw
and abrasive slurry. 40 to 50% of the ingot is lost as sawdust in this process. The ingot is typically
sliced with a pitch of 0.5 to 1 mm to produce wafers with a thickness of 0.3 to 0.5 mm. The wafer
thickness is assumed to be 350 microns and the kerf loss is assumed to be 300 microns, giving a
yield of 54%.
It could be argued that the widespread use of off-spec EG-Si and wafers from the IC industry by PV
manufacturers substantially reduces the energy payback time associated with the wafers, since the
energy content of the EG-Si and wafers could be ascribed to the IC industry. However, this is
inappropriate since the IC industry does not actually make use of this silicon. The end user (in this
case the PV industry) should be charged with the energy content of the silicon, although perhaps
with some sharing of the energy content with the IC industry. In some cases, off-spec IC wafers are
remelted in a Czochralski crystal growth process. In other cases they are cleaned up and used
directly for solar cell substrates. In the former case the energy content of the resulting wafers will be
quite high, since they will have gone through two Czochralski growths. For the sake of simplicity, it
is assumed that the energy content of PV wafers calculated under the assumptions described in
preceding paragraphs holds: a simple flow of silicon from quartz to Czochralski ingot..
Cell fabrication and packaging to form a PV panel
Cell fabrication entails a sequence of high temperature diffusion, oxidation, deposition and annealing
steps. Following metallization, the cells are connected into strings with copper tabs. Panel formation
entails the lamination of the cells behind glass with EVA and Tedlar using heat and pressure. A
junction box is mounted on the back of the panel. In most cases, an aluminium frame is placed
around the panel perimeter. The yield of the cell fabrication and encapsulation process is assumed to
The aluminium frame represents a significant fraction of the panel's embodied energy, but it is not
required with some panel mounting systems. Determination of the energy content of aluminium is
difficult, since it depends on the fraction that is recycled. Determination of the CO2 content is also
difficult. Aluminium is often made using hydroelectricity, which has a small greenhouse impact
(neglecting methane and carbon dioxide emissions from hydroelectric reservoirs, which could, in
fact, be significant even in comparison with a coal fired power station). Thus aluminium production
in Tasmania will have lower carbon dioxide intensity than aluminium production in Queensland.
The wafer area is 110 cm2. After trimming to make a pseudosquare solar cell the area is 100 cm2.
The density of silicon is 2.3 gm/cm3. Thus the mass of each solar cell is 8.1 gm. These cells are
encapsulated to make a PV panel with a packing factor of 91% (i.e. 91% silicon and 9% open space
between the cells).
Balance of systems
The balance of system (BOS) comprises wiring, power electronics, foundations, support frames,
transport and installation. Of these, the support frames and foundations are by far the most energy
intensive. In a system installed in an open field, the foundations are typically concrete while the
support frames are steel. Both of these materials are energy and carbon dioxide intensive. In a
system installed on a building roof, the foundations can generally be dispensed with. In addition, if
the PV array forms part of the roof structure then the energy embodied in the displaced roof
components can be set against the embodied energy in the PV array. Thus the energy payback time
for the BOS components is considerably smaller for roof-mounted systems than for systems
deployed in open field. Systems deployed in open field will generally have smaller inverter and
electrical resistance losses, will have unimpeded access to sunshine and will often be in sunnier
regions than cities. On the other hand, distribution losses will be higher.
It is difficult to estimate the energy savings possible by displacing roofing materials with PV panels,
because many different types of roofing materials are in common use. For example, an aluminium
facade could be replaced with a PV facade, saving large amounts of energy because aluminium is an
energy intensive material. On the other hand, clay tiles or coated steel have relatively low embodied
energy. The replacement of roofing materials with PV panels can introduce the problem of panel
overheating, because the panel will be less able to shed heat from the back surface. On the other
hand, if use is made of the heat generated by the PV panel, which is typically two to three times as
much as the electrical energy output of the panel, then the energy payback time of the PV system
will be very low.
The current energy payback time of a PV panel
A square metre of PV panel will require 90 solar cells with a total mass of 725 gm and an area of 0.9
m2. Allowing for the yield of the Czochralski growth (72%), ingot slicing (54%), cell fabrication
(90%) and cell trimming (90%) processes, a total mass of 2,300 gm of EG-Si is required. A mass of
2,400 gm of MG-Si is required (excluding the silicon that is incorporated into the SiCl4).
Energy payback time (years) for currently produced roof mounted PV systems. The total EPBT is
Energy requirements for each step are assumed to be as follows:
1. Production of MG-Si: 20 kWh per kg of MG-Si produced (15 kWh of electricity is required;
the carbon sources are equivalent to a further 5 kWh of electricity) [2,3]
2. Production of EG-Si: 100 kWh per kg of EG-Si produced [2,3].
3. Production of Czochralski silicon: 210 kWh/kg of EG-Si loaded into the crystal grower [2,3].
4. Cell fabrication: 120 kWh/m2 of silicon [2,3].
5. Panel assembly: 190 kWh/m2 of panel [2,3].
6. Support structure and other BOS costs (open field): 700 kWh/m2 of panel (open field) or 200
kWh.m2 of panel (rooftop) [1-4].
The total energy requirement to produce a PV panel is 1,060 kWh/m2. In Sydney the useable panel
output will be 153 kWh/m2/year, giving an energy payback time (EPBT) for the panel of 6.9 years.
After mounting in an open field or on a roof the EPBT will be 11.5 or 8.3 years respectively. These
energy payback times are well short of the likely system lifetime of 30 years. Figure 1 shows the
energy payback time of the various process steps for a roof-mounted panel. Production of the silicon
wafers accounts for 60% of the total energy payback time.
The energy payback time of a PV panel in 2010
The energy payback time of a PV system in 10 years time is likely to be far lower than the current
figure. Large-scale deployment of PV systems will force costs down, and hence also the energy
content of PV systems. The following assumptions have been used to derive the likely energy
payback time for PV systems in the year 2010:
Thin crystalline silicon solar cells are used, with a silicon consumption of 10% of the current
No aluminium frame is used
Cell processing energy is reduced to 75% of the current value
Direct production of square wafers allows for the elimination of wafer trimming and a
packing factor of 98%
Cell efficiency increases to 18% under standard testing conditions
The PV roof system mounting embodied energy decreases to 75% of the current value
Energy payback time (years) for a roof mounted PV system in the year 2010. The total EPBT is 2.0
After mounting on a roof the EPBT will be two years. The PV module alone has an EPBT of 1.7
years. The PV module is likely to have a similar embodied energy to a currently produced
amorphous silicon module, in which the silicon thickness is only a few microns. The efficiency of
the crystalline silicon panel will be much higher. The energy payback time in Sydney of an
amorphous silicon module (United Solar UPM-880) is estimated to be 2.5 and 1.5 years with and
without an aluminium frame respectively, assuming that the efficiency can be improved from 5% to
The cost of a PV systems will have dropped sharply by 2010, although not as sharply as the
embodied energy because material costs will be less important in future PV systems. Figure 2 shows
the energy payback time of the various process steps for a roof-mounted panel. Embodied energy in
the balance of systems now dominates system embodied energy.
Comparison with coal and gas derived electricity
Australian electricity production is predominantly by means of coal fired power stations. The
Australian Coal Association (ACA) and the Australian Gas Association (AGA) have recently
produced environmental assessments of the production of electricity from coal and gas [6,7]. Both
studies emphasise the importance of a complete life cycle analysis. In the case of natural gas,
fugitive emissions of methane are included. On the other hand, the attraction of direct space heating
and heating of water with gas, in terms of overall greenhouse emissions, is pointed out. In the case of
coal, fugitive emissions such as methane from coal mines are included. On the other hand, the ability
to use waste products to reduce net greenhouse emissions is analysed. For example, fly ash can be
used as an extender in cement production. This 'displacement credit' could potentially reduce the
greenhouse intensity of existing coal fired electricity power stations by around 10% if all the fly ash
were to be used. The ACA and AGA studies are in good agreement with each other with respect to
the greenhouse intensities of the production of electricity from coal and gas.
The ACA study also examined renewable energy greenhouse gas intensities. The carbon dioxide
equivalent intensity of a PV system in Australian can be estimated from the energy payback time as
follows. The national average carbon dioxide equivalent intensity for electricity production is
approximately 0.98 kg of CO2 per kWh . The embodied energy in the PV system can be divided
by the system lifetime (30 years) to calculate the equivalent greenhouse gas emissions per year. The
data is shown in figure 3. The conclusions of the ACA study for photovoltaics are slightly more
optimistic than the conclusions of this study, but do not take into account likely reductions in EPBT
of PV systems over the next decade.
The most important parameter in the determination of the energy payback time of a PV system is the
thickness of the crystalline silicon layer and the method of mounting the panels. Other important
The presence or absence of aluminium components such as panel frames;
The efficiency of the solar cell;
Solar radiation availability;
The ability to use recycled silicon wafers or aluminium;
The details of the cell fabrication process.
Fossil fuel use during PV system operation and decommissioning is negligible. Virtually all of the
fossil fuel energy and carbon dioxide production associated with PV systems arises from the initial
production and installation of the system.
Greenhouse gas intensities for the production of electricity from coal, gas and photovoltaics.
Typical energy payback time at present is around 7 years. Mounting and installation of the system
adds a further 1 to 4 years, depending upon whether it is on a roof or in an open field. This gives a
total energy payback time for a PV system of 8 to 11 years.
Future PV panels that use thin films of crystalline silicon or other materials will have greatly reduced
energy payback times. Such panels will be required if cost targets for large-scale production are to
be met. The expected energy payback time will be in the vicinity of two years. The PV industry is
enjoying production growth rates of about 30% per year, which is likely to bring substantial
investment into the industry. It is expected that thin film PV panels will be in widespread use by
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