Chemistry of Solar Panels

Hopewell Valley Student Podcasting NetworkChemistry ConnectionsLight Up Our WorldEpisode #1  

Welcome to Chemistry Connections, my name is Sarah and I'm Akhansha and we are your hosts for episode #1 called “Light Up Our World”. Today we will be discussing the chemistry behind solar panels.

Segment 1: Introduction to Solar Panels

Solar panels are an alternative, renewable energy source that have gained popularity in recent years. In this episode, we will be explaining how solar panels receive light and produce electricity. But why are solar panels important? Electricity runs the modern world, being necessary for almost all of our daily activities. However, in this day and age, the source of electricity is just as important as electricity itself. *cough* Climate change *cough*. Solar panels provide an alternative pathway to gain energy without harming our world like other sources of electricity. 

Segment 2: The Chemistry Behind TOPIC

So how do solar panels convert light into electricity? Solar panels are made of two types of semiconductors: P-type and N-type. Before we elaborate, we’d like to clarify what a semiconductor is. A semiconductor is a substance that has electrical conductivity between that of a conductor and an insulator. On the periodic table, elements that are semiconductors are silicon, germanium, tin, selenium, and tellurium.

The P-type layer is placed next to the N-type layer. In the P-type layer, atoms with one less electron in the outer shell compared to silicon, like boron and gallium, are added. This absence of an electron is referred to as a “hole” that is positively charged. In the N-type layer, atoms, like phosphorus, that have one more electron in the outer shell than silicon, are added. This creates an excess of electrons in the N-type layers since one electron is free to roam after phosphorus bonds with neighboring silicon atoms. 

Electrons in n-type layer travel to vacancies in p-type layerDepletion zone - area around junction between p-type and n-type layers where electrons fill holesWhen holes are filled in the depletion zone…Negatively charged ions in p-type part of depletion zonePositively charged ions in n-type part of depletion zoneInternal electric field created that prevents more electrons from n-type layer from filling holes in p-type layerSunlight ejects electrons from silicon, creating more holesElectrons are attracted to positive silicon nuclei (opposite charges attract)Energy is needed to break the attractive force between electrons and silicon nuclei

Hopewell Valley Student Podcasting NetworkChemistry ConnectionsLight Up Our WorldEpisode #1  

Welcome to Chemistry Connections, my name is Sarah and I'm Akhansha and we are your hosts for episode #1 called “Light Up Our World”. Today we will be discussing the chemistry behind solar panels.

Segment 1: Introduction to Solar Panels

Solar panels are an alternative, renewable energy source that have gained popularity in recent years. In this episode, we will be explaining how solar panels receive light and produce electricity. But why are solar panels important? Electricity runs the modern world, being necessary for almost all of our daily activities. However, in this day and age, the source of electricity is just as important as electricity itself. *cough* Climate change *cough*. Solar panels provide an alternative pathway to gain energy without harming our world like other sources of electricity. 

Segment 2: The Chemistry Behind TOPIC

So how do solar panels convert light into electricity? Solar panels are made of two types of semiconductors: P-type and N-type. Before we elaborate, we’d like to clarify what a semiconductor is. A semiconductor is a substance that has electrical conductivity between that of a conductor and an insulator. On the periodic table, elements that are semiconductors are silicon, germanium, tin, selenium, and tellurium.

The P-type layer is placed next to the N-type layer. In the P-type layer, atoms with one less electron in the outer shell compared to silicon, like boron and gallium, are added. This absence of an electron is referred to as a “hole” that is positively charged. In the N-type layer, atoms, like phosphorus, that have one more electron in the outer shell than silicon, are added. This creates an excess of electrons in the N-type layers since one electron is free to roam after phosphorus bonds with neighboring silicon atoms. 

Electrons in n-type layer travel to vacancies in p-type layerDepletion zone - area around junction between p-type and n-type layers where electrons fill holesWhen holes are filled in the depletion zone…Negatively charged ions in p-type part of depletion zonePositively charged ions in n-type part of depletion zoneInternal electric field created that prevents more electrons from n-type layer from filling holes in p-type layerSunlight ejects electrons from silicon, creating more holesElectrons are attracted to positive silicon nuclei (opposite charges attract)Energy is needed to break the attractive force between electrons and silicon nucleiElectrons closer to silicon nuclei will be harder for sunlight to eject (Coulomb’s law)Sunlight must have enough energy to remove electrons from silicon atomsDifferent types of solar radiation have different energiesHigher-energy solar radiation (higher frequency light waves) may be more capable of ejecting electronsSolar radiationAlso called electromagnetic radiationLight emitted by the sunthe amount of solar radiation that reaches any one spot on the Earth’s surface varies based off of location, time of day, season, local landscape and local weatherSolar radiation is captured and is turned into useful forms of energyHarder to remove electrons from elements neart the top right of the periodic table (increased Zeff, fewer E-levels)Ejection in electric field → field moves electrons to n-type layer and holes to p-type layerIf n-type and p-type layers are connected with a wire, electrons travel from n-type layer to p-type layer by crossing depletion zone and then through wire out of n-type layer → electricityTwo main types of solar energy technology: Photovoltaics (PV) and Concentrating Solar-Thermal Power (CSP)PhotovoltaicsWhen the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells in the panel This energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flowConcentrating Solar-Thermal powerCSP systems use mirrors to reflect and concentrate sunlight onto receiversReceivers collect solar energy and convert solar energy to heat energyHeat energy can then be converted into usable electricity or can be stored for later use
Segment 3: Personal ConnectionsSolar energy is becoming an increasingly popular form of energySome government programs allow people to save money by switching to solar energyDoor-to-door solar panels sales reps begging people to switch to solarPower outages wouldn't be an issue with solar panelsSarah made a solar-powered phone charger in eighth gradeClimate change sucks

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Sources:

List your sources here. Make sure they are linked. Wikipedia cannot count for more than 50% of your sources.

https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters/past-issues/archive-2013-2014/how-a-solar-cell-works.html https://www.energy.gov/eere/solar/how-does-solar-work#:~:text=When%20the%20sun%20shines%20onto,cell%2C%20causing%20electricity%20to%20flow. 
Music Credits

Warm Nights by @LakeyInspired 

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