OBJECTIVES 1. Solar Cell Technology 2. Solar Systems 3. Key Design and Installation 4. Cost Estimation for Commercial System.

1. PHOTOVOLTAIC
SYSTEM
Kiet Luu
Electrical Engineer
Master Degree

2. WHY SOLAR POWER?
• The world is depleting fossil fuel rapidly
• Global warming
• Renewable energy (PV)
• Each day earth receives 174 solar
Petawatts
• Solar PV price drops rapidly

3. OBJECTIVES
• View of most common PV systems
• Understanding of what are available
• Key Design and Installation
• Basic sizing calculation
• Cost estimate

4. 2 COMMON PV SYSTEMS
• GRID CONNECTED WITHOUT BATTERY
BACKUP
• GRID CONNECTED WITH BATTERY
BACKUP

5. PV
ARRAY
COMBINER
DC
SWITCH
INVERTER
AC
SWITCH
SWITCH
BOARD
METERING
UTILITY
LOADS
PV
ARRAY
COMBINER
DC
SWITCH
INVERTER
ATS
AC
SWITCH
METERING
UTILITY
NORMAL
LOADS
BATTERY
CONT’L
COMBINER
DC
SWITCH
BATTERY
BANK
CRITICAL
PANEL
CRITICAL
LOADS
SYSTEM TOPOLOGIES
Grid connected without battery backup
Grid connected with battery backup
SWITCH
BOARD

6. SYSTEM CHARACTERISTICS
Without Battery
• PV arrays
• Combiner
• Inverter
With Battery
• PV arrays
• Combiner
• Inverter (ATS)
• Battery control
• Battery bank
• Critical Panel

7. SYSTEM CHARACTERISTICS
• GRID CONNECTED WITH BATTERY BACKUP
– Critical loads must be known a priory to size battery
(Which loads? How critical? How long?)
– Battery provide limited coverage period
– System complex and expensive
• GRID CONNECTED WITHOUT BATTERY
– Much common and most cost effective
– Shaving Peak Time
– Grid is down, PV system shuts down
– Virtual battery

8. NOMENCLATURES
Cells Semiconductor device that converts sunlight to DC current
(0.5 volt). It is the building block of the PV system.
Module A group of cells packed together in a safe environment with
easy connection and produce useful voltage and current.
Panels Include more PV modules assembled as a pre-wired,
field-installable unit.
Arrays Is a complete power-generating unit, consisting any number
of PV modules and panels

9. PV HISTORY
• 1839 – French scientist (Edmond Bacquerel) discovers
PV effect.
• 1923 – Albert Einstein received the Nobel Prize for his
photovoltaic theories.
• 1954 – Bell lab report 6% efficient of silicon cell
• 1958 – Vanguard I use solar power and it last 7 years.
• 1976 – Development of polycrystalline cell.
• 1980 – Introduction of Amorphous cells in the market.
• 1990 – Introduction of multilayer of thin film technology
• 2007 – world wide PV capacity reaches 2.8 GW

10. FACTS
• Solar cell material: Semiconductor Silicon
• Effective Spectrum: 0.3-0.6 micron
• Solar cell life: 20 years +
• Inverter life: 5 years
• Battery life: 5 years
• PV Efficiency: 14% (ideal), 10% (normal)
• Solar irradiance: 1000W/m2 (Standard Test Condition)
• PV panel (Thumb rules): 100W/m2, 10W/ft2
• Daily sun light: 4-10 hr per day (Win thru Su )
• Panel weight: 3-4 lbs/ft2

11. SOLAR INSOLATION MAP
Yearly Average of Daily Sunshine in kW-hr

12. SOLAR CELL & PV MODULE

13. SIZING EXAMPLE
• Requirement: 10 KW System
• Size of PV = 10000 W/(100 W/m2) = 100 m2
• Add 20% loss for wiring, inverter, dirty panel
100 m2 * 1.2 = 120 m2
• Working space- add 20%

14. SPREAD SHEET

15. SPREADSHEET

16. SPREAD SHEET

17. INSTALLATION
• Tilt angle facing South
– Flat mounted: lost up to 25% in efficiency
– Improves efficiency
– Tilt angle = Latitude ± Earth axis tilt (15 Deg)
– Improves cooling convection
– Cleaner surface (water & dirt runs off by gravity)
• Mount PV panels with standoff above existing structure
for cooling
• No shading or shadowing

18. PV LARGE SYSTEM

19. PV LARGE SYSTEM

20. PV SYSTEM

21. PV SYSTEM

22. PV SYSTEM

23. SOLAR TRACKER
• Advantage:
– Best Efficiency: 25-40% with single axis.
– Single and dual axes
– When real estate and weight are at premium
– 1st application in Spacecraft such as satellites
• Disadvantage:
– High initial cost
– Maintenance cost

24. SOLAR TRACKER

25. SOLAR TRACKER

26. YOUR SYSTEM
• Grid connected
• Purpose: Power peak shaving
• 3-phase system (vs residential 1-phase)
• Fixed mount (no solar tracker)
• No battery backup
• During outage, the PV system shutdowns

27. DISCUSSION
• Solar irradiance is 4-6 times higher in
Summer than Winter (longer days & rays)
• Optimize the PV system for the Summer
(non tracker system)
• Tilt angle: (32 – 15) degree (San Diego)
facing south (summer optimized)
• Baseline level control
• Conservation 1st & Life Style
• Mixing modules in series is a no!