How solar panels actually work?
In: 75
The UV rays in sunlight (and a bit of heat) excite/”wiggle” the electrons in special materials. By definition, when electrons move you have “electricity”, which you can then store, or use as needed. Think of it like light “hitting” a drum that then vibrates to create a sound/moving air you can hear, or use to do any number of things. Once things start wiggling you can harness them to do work.
Imagine a tube filled with balls. As you add more balls, it pushes earlier balls through the tube. Fundamentally this is what electricity is, you push balls (electrons) down a tube (wires) and that movement is electricity.
Imagine a box with a divider in it. Put all your balls in one side of the box. You pick up a ball and move it to the other side of the divider. Keep doing this until the other side is full and the original side is empty. This is what a solar panel does. It has 2 sides, and photons do what your hand did. When the right photon hits the panel on the correct side, it “picks up” a ball and moves it to the other side. If you were to remove the divider, the balls would fall and even out in the box, but that divider keeps that from happening.
Now, take a bunch of tubes and cut holes onto two sides of the box so that there is 1 hole on each side of the divider. Connect the tubes together. so that one hole connects to the other. Fill one side of the box with balls and start moving them over. There’s now a way for the balls to get from the side you’re filling to the side you’re taking balls from, through those tubes. This is how a solar panel works when it’s connected to a circuit, like into your home or power grid.
Electricity works by something “pushing” electrons through a wire. In solar panels it’s done by pushing electrons through a 1-way barrier and leaving space for electrons on the other side. Photons are what allow electrons to make it through that 1-way barrier. In a traditional generator, magnets are used to push electrons through the wires. In hydrogen fuel cell, the hydrogen is forced through a material that only hydrogen ions can pass through while electrons are forced to go around the material through a wire.
Electricity can be thought of as “What we call it when electrons move around”. Solar panels, otherwise known as photovoltaic cells, work by using special materials that shed electrons when exposed to sunlight. When those electrons are free from their bonds we’re able to capture them via conductive materials in the panel as Direct Current electricity…like turning them into batteries, run them through a transformer and turn them into Alternating Current and power your house.
Normally a solar setup will actually just push its power back into the grid powering your neighbor’s houses and the electric company uses a two-way meter that tracks that production and pays you for it. If you have a battery setup your panels will charge the batteries first, then dump excess power into the grid where the electric company pays you for it. Your house is powered by the batteries until the batteries run out then they start pulling power from the grid. It’s a more complicated setup but it’s more efficient for everyone involved. …And often much gentler on the power grid so if you’re lucky and your power company is desperate enough they may subsidize battery setups.
I think first you need to understand how semiconductors work, otherwise every explanation just boils down to input light output electricity which tells you absolutely nothing you didn’t already know.
So, enter a basic [PN junction, a diode](https://en.wikipedia.org/wiki/P%E2%80%93n_junction#/media/File:Pn-junction-equilibrium.png). P and N being semiconductor materials doped with positive and negative ions respectively. N doped semiconductor has an excess of electrons which leads to conventional conductivity with negative charges, P doped has a shortage of electrons which leads to conductivity of holes – a lack of a electron in crystal lattice works as a positive charge carrier.
Such a junction can be voltage biased two ways. If it’s reverse biased then negative terminal is connected to P type material and attracts positive charges or holes. Positive terminal is connected to N type material and attracts negative charges or electrons. As charge carriers in semiconductor are pulled away from the junction, it’s becomes a isolator, there are no charge carriers to conduct electricity there. The diode does not pass current.
Terminals are flipped if PN junction is forward biased. Holes are pulled towards the N terminal and electrons are pulled towards P terminal, two conductive materials meet and current can pass.
Now interesting thing happens at the junction where excess electrons from N semiconductor recombine with holes in P semiconductor. Holes are really only places in crystal lattice that are short of an electron. So there is a difference in energy levels and electron falls down that potential gradient. Energy can’t really disappear like that so the electron emits a photon in the process.
That is how you get light emitting diodes and all PN junctions emit light, just usually in infrared spectrum, if you have a forward bias 0.6V, a electron falling that potential must emit photon with energy of 0.6 electron volts, which is hc/0.6eV = 2.07micrometers of wavelength.
That process is reversible. If a photon hits a PN junction it can impart energy to electron thus kicking it out of it’s place in crystal lattice and across the junction, which creates current and generates voltage potential. And there you have it, that’s a basic photovoltaic cell.
So you know how LEDs are little lights powered by electricity? Turns out you can work them in reverse too, where shining photons (light) on them produces a little electric charge.
Solar panels are fundamentally just an optimal version of that same technology
There are several kinds of solar panel now. Here’s how a traditional one works.
A photon hits an atom of a special material. The atom is energized. Energized mater is unstable and sheds energy to become stable again. This means the atom poops out an electron. Physics doesn’t like free floating electrons existing, and yeets that electron towards a second special material layered behind the first one. Since that material has the opposite charge of an electron, the panel pushes the electron towards the second material by the most convenient route possible, which just so happens to make the electron flow along some wires. This happens a button of times a second if light keeps hitting the panel, which makes a electrical current.
An electron’s just chilling on the couch when a photon picks him up and throws him on the bus and tells him he can chill on the couch after work. The electron really wants to go home but is stuck in the bus now till he gets to work. When he gets there his boss tells him he can get on the bus going home when he’s done with work. He finishes work and hops on the bus, gets home and chills on the couch till the next day when a new photon comes and throws him on the bus.
Now ELI5 on how solar panel companies work when they try to get panels on your house for free.
There are several kinds of solar panel now. Here’s how a traditional one works.
A photon hits an atom of a special material. The atom is energized. Energized mater is unstable and sheds energy to become stable again. This means the atom poops out an electron. Physics doesn’t like free floating electrons existing, and yeets that electron towards a second special material layered behind the first one. Since that material has the opposite charge of an electron, the panel pushes the electron towards the second material by the most convenient route possible, which just so happens to make the electron flow along some wires. This happens a button of times a second if light keeps hitting the panel, which makes a electrical current.
Now ELI5 on how solar panel companies work when they try to get panels on your house for free.
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