Introduction to Photovoltaics

Dennis ScanlinAppalachian State University

Photovoltaic History• 1839 Edmund

Becquerel - first recognized the effect

Early PV milestones• 1839 – discovery of the

photovoltaic effect; • 1873 – Smith discovers

the photoconductivity of selenium

• 1883 – Fritts develops first selenium cell (1% efficient)

• 1904 – Einstein published his paper on the photoelectric effect (along with a paper on his theory of relativity)

• 1921 – Albert Einstein wins the Nobel Prize for his theories (1904 paper) explaining the photoelectric effect

Albert Einstein

P-N Junction & 1st cells• Technology

Developed at Bell Labs in 1940’s & 50’s

• Patented 1st modern solar cell called a “Light sensitive device”

Vanguard I - first PV powered satellite

• Launched in 1958; 4th artificial satellite

• solar panel: 0.1W, 100 cm²

• Still orbiting; longest orbiting artificial satellite

• $1000/watt

Contemporary Applications:Direct Power Water Pumping or Air Moving

Direct Power

Contemporary Applications:Off Grid Battery Based Systems

Off Grid Battery Based Systems

Offgrid Battery Based System

Hybrid Systems Wind Turbine

Tower

Wind Charge

Controller

Battery Bank

120/240 VAC Loads

DC Loads

DC Source Center PV Charge

Controller

PV Array (Optional)

DC - AC Inverter

System Controls Not Shown

Engine Generator (Optional)

Grid Tied Battery Based Systems

Battery Charging Systems

Direct Grid Tie Batteryless Systems

Direct Grid Tie PV

Direct Grid Tie Inverters

Direct Grid Tied PV: Residential

Number of Residential vs Commercial Systems Installed

Direct Grid Tied Utility Scale Photovoltaic Systems

Annual US Installed Grid PV

Mounting Hardware

Photovoltaic Production, by Country or Region, 1994–2007

0

200

400

600

800

1,000

1,200

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Source: Maycock and Prometheus Institute

Meg

awat

ts

United States Japan Europe China

PV Production by Country

Types of PV Cells/Products

• Single Crystalline

• Polycrystalline

• String Ribbon

• Amorphous or Thin Film

Shipments of PV by Type

Effic

ienc

y (%

)

Universityof Maine

Boeing

Boeing

Boeing

BoeingARCO

NREL

Boeing

Euro-CIS

200019951990198519801975

NREL/Spectrolab

NRELNREL

JapanEnergy

Spire

No. CarolinaState University

Multijunction ConcentratorsThree-junction (2-terminal, monolithic)Two-junction (2-terminal, monolithic)

Crystalline Si CellsSingle crystalMulticrystallineThin Si

Thin Film TechnologiesCu(In,Ga)Se2

CdTe

Amorphous Si:H (stabilized)Emerging PV

Organic cells Varian

RCA

Solarex

UNSW

UNSW

ARCO

UNSWUNSW

UNSWSpire Stanford

Westing-house

UNSWGeorgia TechGeorgia Tech Sharp

AstroPower

NREL

AstroPower

Spectrolab

NREL

Masushita

MonosolarKodak

Kodak

AMETEK

PhotonEnergy

UniversitySo. Florida

NREL

NREL

Princeton

UniversityKonstanz NREL

NRELCu(In,Ga)Se2

14x concentration

NREL

UnitedSolar

United Solar

RCA

RCARCA

RCARCA

RCA

026587136

Spectrolab

University CaliforniaBerkeley

Solarex

12

8

4

0

16

20

24

28

32

36

Best Research-Cell Efficiencies

Concentrating PV

PV Prices

Cost of Energy