Understanding Solar Energy Conversion
FROM
SUNLIGHT
TO ELECTRICITY

The Photovoltaic Journey
Physics 102 · Group 3

Group 3 — Physics 102
OUR TEAM
Layba Zareen Zarrah
252-15-058
01
Md Rezwan UL Karim
252-15-030
02
Nano Sneha
252-15-196
03
Tawaf Sawadul Islam Ryeed
252-15-128
04
S. M. Sayem Hossain
252-15-104
05
Topic 1 · Member 1
WHAT IS SOLAR
ENERGY?
1367 W/m²
Solar constant
~70%
Reaches surface
∞
Renewable
Nuclear Fusion EM Spectrum Clean Energy
Topic 1 · Slide 1.2
Why Solar Matters
GLOBAL
IMPACT
173,000 TW
Striking Earth every second
10,000×
Exceeds global energy demand
Zero Emissions Grid-Scale Space Tech
Topic 2 · Member 2
Einstein · Nobel Prize 1921
PHOTOELECTRIC
EFFECT

Light as discrete quanta — photons — each carrying precise energy, capable of freeing electrons from metal.

E = h · f
h = 6.626×10⁻³⁴ J·s  |  f = frequency
Topic 2 · Slide 2.2
EFFECT IN ACTION
01
Photon Strikes
Light hits metal with energy E = hf
02
Work Function
If E > φ, electron escapes surface
03
KE = hf − φ
Excess energy → kinetic energy
04
Current Flows
Freed electrons → electric current
Topic 3 · Member 3
Member 3 · Silicon Physics
SEMICONDUCTOR
PHYSICS
1.1 eV
Silicon band gap
#1
Most used semiconductor
Valence Band Conduction Band Band Gap Doping
Topic 3 · Slide 3.2
P-N Junction Formation
P-N
JUNCTION
P-Type
Boron doped → holes → positive carriers
N-Type
Phosphorus doped → electrons → negative
Built-in Electric Field ~0.6V
Depletion region — key to charge separation
Topic 4 · Member 4
Member 4
SOLAR CELL
OPERATION
1
Photon Absorption
Light enters anti-reflection coating → reaches junction
2
Electron-Hole Pair
E ≥ band gap → electron excited, hole left behind
3
Charge Separation
Field pushes e⁻ → N-side · holes → P-side
4
DC Output
Electrons flow through external circuit → electricity
Topic 4 · Slide 4.2
Efficiency & Performance
CELL EFFICIENCY
15–22%
Commercial silicon (typical)
29.4%
Shockley-Queisser limit
~47%
Multi-junction lab record
Loss Factors
Reflection · Recombination · Heat (−0.4%/°C above 25°C)
Topic 5 · Member 5
CURRENT APPLICATIONS
🏠
Residential
Rooftop systems cutting bills 50–90%
⚡
Solar Farms
GW-scale plants powering millions
📱
Portable
Calculators, IoT sensors, wearables
🛰
Space Tech
ISS, Mars rovers, deep space probes
Topic 5 · Slide 5.2
Member 5 — The Future
FUTURE INNOVATIONS
🔷 Perovskite Cells
>30% efficiency, cheaper than silicon — decade's biggest leap
⚡ Tandem Multi-Junction
Stack materials absorbing different wavelengths — beyond Si limits
🎨 Solar Paint & Film
Photovoltaic coatings on any surface, transparent window panels
🔋 Smart Grid + V2G
AI-optimized solar + vehicle-to-grid + peer-to-peer trading

"The sun delivers more energy in one hour than humanity uses in an entire year."