SINGLE CRYSTAL SILICON PV CELLS www.solarcell.net
PARTS OF A SOLAR CELL • Electrically conductive grid on top surface to carry electrons • 1-2 layers of anti-reflective coating to increase absorption • The collector: a thin layer of silicon • An electrode in contact with base layer to complete the circuit.
SILICON • Silicon is the most popular PV material • Most cells are made from left over computer chip manufacturing • Silicon must be refined to almost 100% purity • The uniform molecular structure of silicon makes it efficient for electron transport • Silicon wafers are cut from ingots
CZOCHRALSKI PROCESS • This is the process of creating an ingot. • A small single silicon rod (seed) is placed in an inert gas at high temps. • When the seed is rotated up and out silicon adheres to it to form an ingot.
CELLS -> MODULES • Wafers 5 inches square and .012 inches thick are sliced from the ingot. • They are then processed into cells and soldered together to achieve the desired voltage. • Cells arrayed in series are called modules.
TWO TYPES OF CELLS • There are two types of single crystal silicon cells: n-type or p-type
TECHNOLOGY • PV cells exhibit voltage or current when exposed to light. • The light liberates electrons which move through the cell creating current. • The larger area there is the more current. • Single crystal silicon cells are the most efficient at 15-24% sunlight-to-electricity conversion rate. • They are also the most expensive to produce at $6.50/ watt.
MANUFACTURERS • Sharp Electronics Corporation • Sanyo • bp Solar • Shell • Sunwise • Uni-Solar • AstroPower
Shell: 80 watt panel 47.2”x20.8”x1.3” $328.00 AstroPower: 75 watts 47.2”x20.7”x1.4” $325.00 PRICE COMPARISONS • Sunwise: • 85 watt panel • 56.89”x22.83” • $351.00
BIBLIOGRAPHY “Photovoltaic Materials-Silicon”. www.azom.com/details.asp?ArticleID=1169 SOLARTROPE Supply Corporation. 2002. www.solartrope.com. Resource Center Technologies. G/rated. www.green-rated.org/resctr_tech.asp?id=1 www.physics.pomona.edu/COURSES/phys17/papers/PV.pdf www.mrsolar.com www.oksolar.com