Emma ResorSOLAR ENERGY

Different kinds of solar energySolar water heating

Very effective solar technologies15

Use heat energy from the sun to produce hot water15

Solar energy (photovoltaic energy) Popular technology which

converts the sun’s rays into usable energy through solar panels11

SOLAR ENERGY BASICS

I

II

PHOTOVOLTAIC CELLS: BASICS4

III

Account for 90% of PV product sales in 2011

Many formsSingle-crystalline (c-Si) is the most popularMulticrystalline wafers sawn from ingotsMelt-grown ribbonsThin hydrogenated amorphous silicon (a-Si:H)Microcrystalline Si layers grown from gaseous precursors

Averages 24% effi ciencyCurrently researching higher effi ciency

crystalline Si

SILICON CELLS16

Ultra-thin layer of phosphorus-doped silicon on top of a thicker layer of boron-doped silicon. 

P-N junctionTypical silicon cell produces about 0.5V to

0.6V DC

HOW PV CELLS WORK8

V

IV

Starts with pure semiconductor-grade polysiliconSilicon is melted and trace amounts of phosphorous

and boron are added to separate batches of liquid silicon

It is poured into molds, and an ingot is formedSilicon is sliced from blocksSubjected to a surface etching process

HOW PV CELLS ARE MADE7

VI

Anti-reflective coating is appliedElectrical contacts are imprinted on the top

(negative) surface An aluminized conductive material is

deposited on the back (positive) surface of each cell

Each cell is electrically tested and sorted Then electrically connected to other cells

HOW PV CELLS ARE MADE7

MODULES, PANELS, AND PV ARRAYS3

PV Cells: the layers of doped

semiconductor in a

single unit

PV Module: consists of

PV cell circuits

PV Panel: one or more PV modules

PV Array: the

complete power-

generating unit

Batteries are sometimes attached to store excess energy

PV SYSTEMS ENERGY STORAGE6

VII

Grid-connected (or utility-interactive) Designed to operate in parallel with and

interconnected with electric grid PV output can be utilized on-site Home can still pull power from the grid

Stand-Alone Designed to operate independent from the electric

grid Generally designed and sized to supply specific DC/AC

electrical loads Simplest S-A is the direct-coupled system

No electrical storage S-A with battery storage

SPECIFIC PV SYSTEMS18

Arrangement of solar panels depends on site

SOLAR PROJECTS12

An

gle

d P

an

els

(in

Fi

eld

s)

• Facing south• Generally

has a 15 to 30 degree angle

Sun

Tra

cker

Panels

• Follow the sun’s progression

• More efficient

Roof-

Moun

ted

Panels

• Used to powers individual houses

• Angle depends on roof

XIXVIII

For single-junction cells, energy output is limited by material’s band gap (threshold frequency/work function)

Multijunction cells get around this problem Higher total conversion effi ciency Arrangement - different kinds of cells are stacked

Silicon solar cells become significantly less effi cient at higher temperatures

RESTRICTIONS OF PV CELLS13

What most solar cells can absorb

XI

47% converted to heat13

18% of photons pass through the solar cell13

2% is lost from local recombination of newly created holes and electrons13

Solar Coeffi cientUsually it’s negative – meaning that when temperature rises above 25°C, the solar material gets less efficient.16

ENERGY LOSS IN PV CELLS

Boosting solar cell conversion effi ciencies12

Lowering the cost of solar cells, modules, and systems12

Improving the reliability of PV components and systems12

Challenges Storing enough energy so that homes do not

experience blackouts12

Different materials for PV cells are being explored12

Looking into Thin-Film PV technology17

PHOTOVOLTAIC CELLS: RESEARCH FOCUS

Gallium Arsenide as opposed to Silicon Pros

Temperature coeffi cient is effectively 09

Has a lower threshold frequency13

Panel Production10

Cons Very new and not fully

tested10

Gallium Arsenide cells are expected to dominate solar industry10

ALTERNATIVE CELL

XII

Today, electricity production annually generates:2

40% of U.S. carbon emissions2

$100 billion in health impacts2

$160 billion in related costs from blackouts and power outages2

Untold additional costs from air, land, and water pollution2

UNSUSTAINABLE ENERGY

US ENERGY SOURCES - 2013

XIII

AestheticPeople don’t like the look of solar panels

SafetyGenerally safe

LocationConveniencePermit Process – restrictions

Creating jobsPersonal/emotional effects

SOCIAL ASPECT12

Solar is very expensiveHowever, costs of

traditional energy are rising significantly whereas solar becomes less expensive as the technologies improve Federal tax credits/breaks

(30%, but can vary by state)

Panels pay for themselves Time varies by location

ECONOMIC EFFECT1

ENERGY COST BY STATE20

WEST VIRGINIA: CONSUMPTION20

WEST VIRGINIA: PRODUCTION20

WEST VIRGINIA: PRICE20

MARYLAND: CONSUMPTION20

MARYLAND: PRODUCTION20

HAWAII: CONSUMPTION20

HAWAII: PRODUCTION20

HAWAII: PRICE20

http://www.eia.gov/state/maps.cfm?v=Energy%20Infrastructure

WORLD ENERGY20

PV electricity contributes 96% to 98% less greenhouse gases than that generated from coal19

Uses 86% to 89% less water19

Occupies or transforms over 80% less land19

Presents approximately 95% lower toxicity to humans19

Panels pay for themselves in terms of energy5

ENVIRONMENTAL IMPACTS OF SOLAR

XIV

1 Bennett, Rachel. "Can I Really Save Money by Putting Solar Panels on My Roof?" NerdWallets MoneySaving Tips . 21 Aug. 2012. Web. 13 May 2014.

2 "Bringing Clean Competit ive Solar Power to Scale."  Rocky Mountain Institute . 12 May 2014.

3 "Cells, Modules, and Arrays." Florida Solar Energy Center . F lor ida Solar Energy Center. 13 May 2014.

4 "Current PV Technologies." Florida Solar Energy Center . F lor ida Solar Energy Center. 13 May 2014.

5 Fthenakis, Vasi l is. How Long Does It Take for Photovoltaics To Produce the Energy Used? National Society of Professional Engineers, February 2012. PDF

6 "How A PV System Works." Florida Solar Energy Center . F lor ida Solar Energy Center. 13 May 2014.

7 "How PV Cells are Made." Florida Solar Energy Center . F lor ida Solar Energy Center. 13 May 2014.

8 "How PV Cells Work." Florida Solar Energy Center . F lor ida Solar Energy Center. 13 May 2014.

9 Kapusta, Rich. "Si l icon vs. Gall ium Arsenide Which Photovoltaic Material Performs Best." Tech Briefs . NASA, 1 Jan. 2014. 14 May 2014.

CITATIONS: INFORMATION

1 0 "PV Technology Overview." GroSolar Tech Talk. MD, Columbia. 21 May 2014.

1 1 "Solar Energy Basics." Florida Solar Energy Center . Florida Solar Energy Center. 13 May 2014.

1 2 Resor, Jamie P. "Solar Cells." Interview by Emma B. Resor. 25 May 2014. Lecture.

1 3 “The Shockley Queisser Effi ciency Limit” Solar Effi ciency Limits . 17 May 2014.

1 4 "Solar." Energy.gov . U.S. Department of Energy. 12 May 2014. 1 5 "Solar Hot Water." Florida Solar Energy Center . Florida Solar Energy

Center. 20 May 2014. 1 6 "Sil icon Materials and Devices R&D." NREL: Photovoltaics Research .

U.S. Department of Energy. 12 May 2014. 1 7 "Thin Fi lm PV." Florida Solar Energy Center . Florida Solar Energy

Center. 13 May 2014. 1 8 “Types of PV Systems." Florida Solar Energy Center . Florida Solar

Energy Center. 13 May 2014. 1 9 “Why It’s Time for Businesses To Wake Up To The Benefi ts Of Solar

PV.” Think Renewables . 20 May 2014 2 0“Maps.” U.S. Energy Information Administration – EIA . 26 May 2014

CITATIONS: INFORMATION

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CITATIONS: PICTURES

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Graphs from slide 21 on: “Maps.” U.S. Energy Information Administration – EIA . 26 May 2014

CITATIONS: PICTURES