The document provides an extensive overview of photovoltaic (PV) solar systems, covering aspects such as solar energy theory, performance parameters, types of PV cells, sizing, efficiency factors, wiring, components, and installation tips. It delves into the practical and financial viability of PV systems while also addressing various technologies and market trends in solar energy. The document serves as a comprehensive guide for understanding and evaluating PV solar systems and their implementation.

1. 1
PV Solar Systems
By
Professor Moustafa M. Elsayed
Consultant, EGEC
moustafa.elsayed@egec-xprt.com
1
Contents
• Solar Energy on Earth
• PV Theory
• I-V Curve of PV Cell
• PV Performance Parameters
• Types of PV Cells
• PV Cell, Panel, and Array
• Rough Sizing of PV Array
• Efficiency Drop
• PV Panels Wiring
• Components of PV Systems
• Grid Connection
2
• Installation Tips
• PV System Costs
• PV Cell Producers
• PV Power Plants
• Factors Affecting Power
Production
• PV System Viability
• References

2. 2
http://en.wikipedia.org/wiki/File:Breakdown_of_the_incoming_solar_energy.svg
Solar Energy on Earth - 1
P = Peta = 1015
3
• The total solar energy absorbed by Earth's atmosphere, oceans and land
masses = 3,850,000 exajoules per year(Exa =1018).
• About 70% of Solar Energy is incoming sunlight
• Primary energy use (2005) 487 EJ (0.0126%)
• Electricity (2005) = 56.7 EJ (0.0015%)
• Photosynthesis captures approximately 3,000 EJ per year in biomass.
• The amount of solar energy reaching the surface of the planet is so vast that in
one year it is about twice as much as will ever be obtained from all of the
Earth's non-renewable resources of coal, oil, natural gas, and mined uranium
combined.
http://en.wikipedia.org/wiki/Solar_energy
Solar Energy on Earth - 2
4

3. 3
5
PV Theory - 1
6
(V)
(A)
Voltage(V)
Current(I)
P
N
A
Short Circuit
Open Circuit
P
N
V
about 0.5V
(Silicon)
High insolation
•Voltage on normal operation point
0.5V (in case of Silicon PV)
•Current depend on
- Intensity of insolation
- Size of cell
Low insolation
Normal operation point
(Maximum Power point)
I x V = W
I-V Curve of PV Cell: Definition

4. 4
7
(V)
(A)
Voltage(V)
Current(I)
0.49 V 0.62 V
4.95A
5.55A
Depend on
type of cell or cell-
material
( Si = 0.5V )
Depend on cell-size
Depend on
Solar insolation
I-V Curve of PV Cell: Typical I-V Curve
8
P
N
A
V
• To obtain maximum power, current
control (or voltage control) is very
important.
(V)
(A)
Voltage(V)
Current(I)
I x V = W
P2
PMAX
P1
Vpmax
Ipmax
I/V curve
P- Max control
• “Power conditioner” will adjusts to
be most suitable voltage and current
automatically.
Power curve
I-V Curve of PV Cell: Maximum Power of PV

5. 5
9
(V)
(A)
Voltage(V)
Current(I)
12
10
8
6
4
2
0
0 0.1 0.2 0.3 0.4 0.5 0.6
P
N
A
)
(
05
.
0 Ω
=
R
PV character
( I/V curve )
If the load has 0.05 ohm resistance,
cross point of resistance character and
PV-Character will be following point.
Then power is 10x0.5=5 W
)
(
05
.
0 Ω
=
R
05
.
0
/
V
I =
R
V
I =
Ohm’s theory
I-V Curve of PV Cell: Load Power
• Capacity Factor (CF): Annual generation divided by generation that would result
from system operating at full capacity all day everyday
• Capacity Factor (CF) = (Annual kW.hr generated) ÷ (Rated Capacity x 8760
hours/year)
• Notes:
– It depends considerably on geographical location.
– Generally, it is in the range of 10-25%.
– Annual Capacity Factor is about 19% (Tracking is 20%)*
– Summer Capacity Factor is about 24% (Tracking is 28%)*
– Spring and Fall is about 20% (Tracking is 20%)*
– Winter is about 13% (Tracking is 13%)*
• Example: Fixed-tilt 6 MW PV farm generates 9526 kW.hr/year
CF = (9526 kW.hr per year) ÷ (6 MW x 8760hr/year) = 0.181
• Conversion Efficiency
PV Performance Parameters - 1
10
Conversion Efficiency =
Electric Energy Output
Energy of Insolation on cell
x 100%

6. 6
DC to AC Derate Factor
• PV System Ratings may be DC or AC
• AC Rated Capacity = DC Nameplate
Capacity x DC to AC Derate Factor
• DC Nameplate Capacity is the sum of
the module nameplate nominal DC
power ratings at Standard Testing
Conditions (not real world)
PV Performance Parameters - 2
• DC to AC Derate Factor takes into account real world operating
conditions, system inefficiencies and conversion losses from DC
to AC power.
• Typical DC to AC Derate factors for commercial and industrial
scale PV systems are 85% to 90%.
• Today’s inverters have very high DC to AC conversion efficiencies
(more than 95%)
Typical 500 kW Inverter - 96% Efficient
11
12
http://www.commdiginews.com/environment/solar-and-wind-electric-a-matter-of-land-area-10383/
PV Performance Parameters – CF Comparison

7. 7
1. Monocrystalline silicon cell: produced from pure silicon
(single crystal).
2. Polycrystalline solar cell: liquid silicon is used as raw
material and polycrystalline silicon was obtained followed by
solidification process.
3. Amorphous silicon: is obtained by depositing silicon film (to
less than 1µm) on the substrate like glass plate.
Types of PV Cells – Basic Types
Material Efficiency (%)
Monocrystalline silicon 10-17
Polycrystalline silicon 10-13
Amorphous silicon 7-10
14
Crystalline
Non-crystalline
Single crystal
Poly crystalline
Amorphous
Gallium Arsenide (GaAs)
Conversion Efficiency
of Module
10 - 17%
10 - 13%
7 - 10%
18 - 30%
Conversion Efficiency =
Electric Energy Output
Energy of Insolation on cell
x 100%
Dye-sensitized Type
Organic Thin Layer Type
7 - 8%
2 - 3%
Silicon
Semiconductor
Compound
Semiconductor
Solar
Cell
Organic
Semiconductor
Types of PV Cells - Review (As per 2008)

8. 8
Solar Cells 2010 Market Share Estimate
0%
10%
20%
30%
40%
50%
Type
Market
Share
-- First Generation -- -- Second Generation -- - Third Gen -
SEMI PV Group March 2009 from source Yole Development
Types of PV Cells: Market Share
15
16
http://www.speedace.info/solar_cells.htm
Types of PV Cells: Conversion Efficiency

9. 9
17
http://www.solarbuzz.com/news/recent-findings/efficiency-enhancements-define-solar-pv-
technology-roadmap-next-five-years-acco
Technology Roadmap Scenario Forecast by PV Technology Type
Types of PV Cells: Technology Road Map
18
2 – 3 W
100 - 200 W
10 - 50 kW
Cell
Array
Module,Panel
Volt Ampere Watt Size
Cell 0.5V 5-6A 2-3W about 10cm
Module 20-30V 5-6A 100-200W about 1m
Array 200-300V 50A-200A 10-50kW about 30m
6x9=54 (cells) 100-300 (modules)
PV Cell, Panel, and Array

10. 10
19
How much PV can we install in this conference room?
1 kw PV need 10 m2 Please
remember
10m(33feet)
20m(66feet)
Conference
Room
(We are now)
Our room has about 200 m2
We can install about
20 kW PV in this room
(108 feet2)
(2,178 feet2)
Rough Sizing of PV Array
20
4
4
4
4
6
6
6
6
8
8
8
8
10
10
10
10
12
12
12
12
14
14
14
14
0
0
0
0 10
10
10
10 20
20
20
20 30
30
30
30 40
40
40
40 50
50
50
50 60
60
60
60 70
70
70
70 80
80
80
80 90
90
90
90 100
100
100
100
Module Temperature (deg.C)
Efficiency
(%)
Crystalline cell
Amorphous cell
Typical
(25C)
Summer time
on roof top
(65C)
2%
down
• When module temperature rises up, efficiency decreases.
• The module must be cooled by natural ventilation, etc.
Efficiency Drop: Temperature Effect

11. 11
• As insolation
decreases
amperage
decreases while
voltage remains
roughly
constant
Efficiency Drop: Effect of Shading
21
PV Panels Wiring
22
Series Connections
Loads/sources wired in series
Sum of Voltages but same
current
Parallel Connections
Loads/sources wired in parallel
Sum of Currents but same Voltage

12. 12
• Modules
• Storage: batteries, tank
• AC utility net meter
• Power conditioner
Inverter or DC to AC Converter
Charge controller
• Voltage Step up
Components of PV Systems - 1
23
Components PV Systems - 2
24

13. 13
• PV Integration
Distributed
Centralized
• Grid-Type
Central
Isolated
• Not usually
cost-effective
without subsidies
(till Y2013)
Grid Connection: On-Grid Systems
25
• Configuration
Stand-alone
Hybrid
• Often very cost-effective
Small loads best ( 10 kWp)
Lower capital costs than
grid extension
Lower OM costs than gensets and
primary batteries
Grid Connection: Off-Grid Systems
26

14. 14
Installation Tips: Solar Angles - 1
27
Sun Azimuth: measuring convention?
Installation Tips: Solar Angles - 2
28

15. 15
Installation Tips: Panels Orientation and Tilt
29
Max performance is
achieved when panels
are perpendicular to the
sun’s rays
Tilt:
Year round tilt = latitude
Winter + 15 lat.
Summer – 15 lat.
Orientation:
Facing Equator
Effective Period of Solar
Energy Collection:
9:00 AM to 3:00 PM in
winter (see sun path
chart)
30
http://www.terrafirma-solutions.com/articles/solar-pv-rooftop-revolution/
PV System Costs - 1

16. 16
• Levelized Cost of Energy
(LCOE) is the price at
which electricity must
be generated from a
specific source to break
even over the lifetime
of the project.
• It is the cost of the
energy-generating
system including all the
costs over its lifetime:
initial investment,
operations and
maintenance, cost of
fuel, cost of capital.
31
PV System Costs – LCOE
http://en.wikipedia.org/wiki/Cost_of_electricity_by_source#Levelized_Cost_of_Energy
As per 2013
32
http://en.wikipedia.org/wiki/Cost_of_electricity_by_source
PV System Costs – PV LCOE in Europe

17. 17
$1.35
$1.07
$0.81
$0.54
$0.27
$0.13 ---
$/kWh
“Grid parity’ where PV cost
are equal to residential
electricity costs is
expected to be achieved
first in southern European
countries and then to
move north
PV System Costs : Projections
33
34
http://www.powerclouds.com/index.php/economic-benefits/
PV System Costs – Components Share

18. 18
35
http://pradeepchakraborty.wordpress.com/2010/12/21/top-15-producers-of-c-si-and-thin-film-solar-pv-
modules-and-outlook-2011/
PV Cell Producers: Top Producers (2010)
36
http://nenmore.blogspot.com/2013_11_01_archive.html
PV Cell Producers: Production by Technology

19. 19
Name of PV power plant Country DC
Peak
Power
(MW)
GW·h
/year
Notes
Olmedilla Photovoltaic Park Spain 60 85 Completed September 2008
Puertollano Photovoltaic Park Spain 50 2008
Moura photovoltaic power station Portugal 46 93 Completed December 2008
Waldpolenz Solar Park Germany 40 40 550,000 First Solar thin-film CdTe
modules. Completed Dec 2008
Arnedo Solar Plant Spain 34 Completed October 2008
Merida/Don Alvaro Solar Park Spain 30 Completed September 2008
17 more
2 more
Spain
Korea
Avg 20
Avg 20
Koethen Germany 14.75 13 200,000 First Solar thin-film CdTe
modules. Completed Dec 2008
Nellis Solar Power Plant USA 14.02 30 70,000 solar panels
Planta Solar de Salamanca
6 more Spain, 1 US, 1 Germany
Spain 13.8
Avg 12
n.a. 70,000 Kyocera panels
http://en.wikipedia.org/wiki/Photovoltaic_power_stations
PV Power Plants: World 12 MW or Larger
37
38
http://www.abb-conversations.com/2013/12/7-impressive-solar-energy-facts-charts/
PV Power Plants: World Shares

20. 20
http://lumbergusa.com/main/Bild/sp_pv_07/Brandis-Waldpolenz-Fotomont.jpg
PV Power Plants: Waldpolenz Solar Park
39
• Geographical location
• Orientation tilt angles of PV arrays
• Temperature (lower is better)
• Shadowing (no shadows best)
• Cleanliness of panels (dirt on panel impedes sunlight)
• Inverter efficiency
• System age (systems degrades but typically at 1% per year)
• Wiring and other electrical losses (typically 3%)
Factors Affecting Power Production
40

21. 21
Technical Evaluation:
• Area of roof or area proposed for system
• Structural
• Solar intensity for location
• Interconnection
• Panel manufacturer and technology (determines
efficiency)
• Possible power output vs. desired output
PV System Viability – Technical Evaluation
41
Financial Evaluation
• Determine cost of installation
Materials: Solar Panels, Racking and mounting system(s), Inverter,
Net meter, Wiring
Labor: Design, Permitting, Installation labor
Other: Land, Tracking system
• Determine maintenance and recurring costs
• Determine revenue from electricity and renewable energy
credit (REC) sales
• Determine credits and tax benefits
• Develop a financial model of project and calculate
payback time and Return on Investment (ROI)
PV System Viability – Financial Evaluation
42

22. 22
Resources for Technical and Financial Evaluation
• National Renewable Energy Laboratory: PV Watts (tool to
analyze power output, free download),
http://pvwatts.nrel.gov/
• SAM, System Advisor Model, NREL National laboratory of the
U.S. Department of Energy,
https://sam.nrel.gov/content/downloads
• Natural Resources Canada: RETScreen (tool for financial
analysis and power output calculations, free download),
http://www.retscreen.net/
• Other Web Software: There are many other software
programs available on web that could be use (free download
or against fees)
PV System Viability – Tools for Evaluation
43
PV System Viability – Example
Example
• A PV system of 100 kW DC will be built in Cairo, Egypt. The
system has the following basic information:
• Initial cost of $1000/kW.
• System will be connected to grid at tariff of 0.84 EGP/kW.hr
• Study the Viability of this system
System Evaluation
• Use RETScreen 4 software
• Results are shown in following reports:
• Input data
• Model Results
44

23. 23
PV System Viability – Example (… continued)
Results
• Payback period = 5.5 years
• PV array area required for the project = 743 m2
• Annual MW.hr exported to grid = 172 MW.hr
• Average kW generated = 172*1000 / (24*365) = 19.6 kW
• Plant Capacity Factor = 19.6/ 100 = 19.6%
45
References
46
1. Herb Wade Consultant (2008), Solar PV Design Implementation O M, Power Point Presentation in E8, Marshall
Islands, March 31- April 11, 2008.
2. Barbara Summers Brian Chiu (2008), Photovoltaic Design and Installation, PP Presentation, Bucknell
University Solar Scholars Program.
3. Dick Saunders and David Keenan (2009), Photovoltaic Solar Energy Futures , Presented to the Minnesota
Futurists ,16 May 2009.
4. http://photovoltaic-software.com/ , accessed during Nov. 2014
5. http://en.wikipedia.org/wiki/Cost_of_electricity_by_source. Accessed on 20-Nov-2014.
6. http://www.abb-conversations.com/2013/12/7-impressive-solar-energy-facts-charts/. Accessed on 20-Nov-
2014.
7. Darwish, M. A;. Abdulrahim, H. K; and Sharif, A. O. (2014), Photovoltaic Power Stations (PVPS), Qatar
Environment and Energy Research Institute (QEERI) – Qatar Foundation, Qatar
8. National Renewable Energy Laboratory: PV Watts (tool to analyze power output, http://pvwatts.nrel.gov/ ,
accessed during Nov. 2014
9. International Energy Agency (IEA), Technology Roadmap Solar Photovoltaic Energy_2014 edition
10. Natural Resources Canada: RETScreen (tool for financial analysis and power output calculations,
http://www.retscreen.net/, accessed during Nov. 2014
11. Shawn Fitzpatrick (2013), Advanced Energy, PV Market Trends and Technical Details, PP presentation available
on Web, accessed in Nov. 2014
12. SRM University (2007), PP Presentation for PH 0101 Unit-5 Lecture-2.
13. SAM, System Advisor Model, NREL National laboratory of the U.S. Department of Energy,
https://sam.nrel.gov/content/downloads . Accessed on 17Nov-2014

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