Introduction to Solar Photovoltaic (PV) Systems – Part 2 Introduction to the Concepts of: Sustainability (The Big Picture) How Solar Photovoltaic Cells work How Solar Photovoltaic (PV) System works

Agenda Ice Breaker Game Lecture on: PV Cell Lab Sustainability (The Big Picture) How Solar Photovoltaic Cells work How Solar Photovoltaic (PV) System works PV Cell Lab

Ice Breaker Group Activity Your teacher will assign each of you a word and you need to define it in your own words. Write down your own definition on a piece of paper. Your group can help you if you are completely lost on how to define the word. Go around the classroom and read your word and your own definition out loud.

Ice Breaker: Energy Photovoltaic Power Voltage Fission Physics Direct Current (DC) Alternate Current (AC) Power Inverter Energy Management Current Efficiency Sustainability Electric Circuit Conservation of Energy Charge (Electrons) Environment Fusion Series Circuit Parallel Circuit

The Big Picture – Sustainability: Capacity to Endure Environment Economic Social Human Consumption Natural & Physical Resources Energy Biofuel, Biomass, Geothermal, Hydropower, Tidal, Wave, Wind, and Solar

Solar Technologies Solar Energy Solar Power Biological Environments Architecture & Urban Planning Biological Environments Photovoltaics Water Heating Building Heating Photosynthesis Charge Controller Batteries Inverter

Nuclear Energy (Fusion) Energy Conservation Energy cannot be created or destroyed, it can be only transferred from one form to another. Sun Earth Nuclear Energy (Fusion) Solar Radiation Photovoltaic Systems Electrical Energy

Semiconductor Devices – Basics Charge can be positive (holes) or negative (electrons) Silicon (Si) is an atom with 4 valence electrons. In pure silicon it is difficult to control conductivity. n-type semiconductor – Silicon with impurity atoms having 5 valence electrons. p-type semiconductor – Silicon with impurity atoms having 3 valence electrons.

Physics of Photovoltaics N-type silicon Pure silicon P-type silicon

How Photovoltaics Work? A negatively charged electron in the n-type silicon layer is repelled by the diode and can’t move through to the p-type silicon layer. { N-type Silicon Layer Junction where electrical field or diode is formed P-type Silicon Layer { { A negatively charged electron in the p-type silicon layer can move through the diode to the n-type silicon layer.

PN - Junction

How Photovoltaics Work? Solar energy (photons of light) hit the cell, passing through the n-type layer and releasing electrons from atoms in the p-type layer. These electrons pass upwards through the diode and to the n-type layer. N-type Silicon Layer Junction where electrical field or diode is formed P-type Silicon Layer PN Junction

How Photovoltaics Work? Metal conductors are added to the top and bottom of the cell and are connected to an electrical load. This creates an electrical circuit. Metal Conductor Junction where electrical field or diode is formed

Light Emitting Diode (LED) A LED is an electronic light source. When a voltage is applied, electrons combine with holes and energy is released in the form of light.

A Photovoltaic (in Concept) In concept, a Photovoltaic is an LED working in reverse.

Photovoltaics

Cell -> Panels -> Arrays

Efficiency of Photovoltaics

Photovoltaics - Efficiency

How to Improve Efficiency? Higher Efficiency = Lower Ohmic Losses Ohmic Loss – Occurs when charges move through a conductor. Higher Efficiency = Lower Dielectric Losses Dielectric Loss – Occurs when plates and/or any other adjacent contacts or surfaces are charged or discharged.

Photovoltaic System (One) Components of a Photovoltaic System

Photovoltaic System (Two)

Photovoltaic System Components Inverter Converts DC power from solar array to AC for use in your home Wiring Connects the system components Batteries Used to store solar-produced electricity for nighttime or emergency use Charge Controller Prevents batteries from being over charged Disconnect Switches Allows power from a PV system to be turned off Electrical Meter Measures electrical production and use

Deep Cycle Batteries and Inverters Deep Cycle Batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates. Can’t provide large current surges.

Inverters Inverter is the device that transforms direct current (DC) to alternating current (AC). Can provide 115VAC from a 12 VDC. Consider Efficiency and Power Rating. Efficiency =

Wiring Photovoltaics - Series Photovoltaics in Series Increases Voltage Available current is limited by individual photovoltaics. 135 W 12 V 11.25 A Ammeter 11.25 A Voltmeter 36 V

Wiring Photovoltaics - Parallel Photovoltaics in Parallel Increases Available Current Individual connected photovoltaics should be rated for the same voltage. Ammeter 33.75 A Each Panel: 135 W 12 V 11.25 A = 405 W Voltmeter 12 V

DC versus AC Direct Current (DC) Alternating Current (AC) Can be stored. Can only be sent over short distances due to losses. Easy to manipulate Change level (Voltage) Flow rate (Current) Alternating Current (AC) Can’t be stored. Can be sent long distances with low losses. Difficult to manipulate It is possible but requires usually larger and more complex circuits and devices.

Solar Modules and Arrays

Solar PV Systems Cells are the building block of PV systems Typically generate 1.5 - 3 watts of power Modules or panels are made up of multiple cells Arrays are made up of multiple modules A typical array costs about $5 – $6/watt Still need lots of other components to make this work Typical systems cost about $8/watt

Florida Solar Energy Center

PV Modules have efficiencies approaching 17% Florida Solar Energy Center

Florida Solar Energy Center

Solar Panel Solar panel by BP Solar at a German autobahn bridge Solar panels are devices for capturing the energy in sunlight. The term solar panel can be applied to either solar hot water panels (usually used for providing domestic hot water) or solar photovoltaic panels (providing electricity). Solar panel by BP solar at a German autobahn bridge. pic taken 4/04 by Thomas Springer. Solar panel by BP Solar at a German autobahn bridge http://en.wikipedia.org/wiki/Solar_panel

Florida Solar Energy Center

PV Cell Laboratory - Tomorrow The purpose of this lab is to give students experience constructing operating circuits while reviewing the following ideas/concepts: • Voltage • Current • Power • Energy/work • Photoelectric effect • Series/Parallel circuit design • Efficiency