How Fast Does Electricity Travel?

ResidentialCalendarJanuary 7, 2019

Electricity is the flow of electrons through a conductor in an electrical field. In the case of an electrical cord connecting a table lamp or some other household item to a power source, the copper wire inside the cord acts as the conductor. 

This energy travels as electromagnetic waves at about the speed of light, which is 670,616,629 miles per hour,1 or 300 million meters per second.2 However, the electrons themselves within the wave move more slowly. This concept is known as drift velocity.

What is the speed of electrons in electricity?

Electrons are negatively charged. Some are fixed as part of the atom, and some move freely around the stable grid of a conductor made of secure atoms. When the free electrons bounce around, they create an electrical charge.3

The number of electrons that are able to move around in a particular material determines how conductive it is. Some materials, such as the copper wire inside electrical cords, allow electrons to move around more freely—and, therefore, conduct electricity better. 

Since electrons are negatively charged, they are propelled in the opposite direction of the positive charge. Soon, the free electron hits a stable atom and bounces off in another direction somewhat randomly. 

While this energetic bouncing creates an electrical charge, the electrical current isn’t much use without some direction. That’s where an electrical force to move the electrons in one direction comes in. This is called an electromagnetic force (EMF).4

The Basics of Electrical Currents

Electrical currents can be compared to the flow of water in a pipe: the more pressure at one end, the stronger the flow of water (or electricity).5 Connecting a wire to a battery or a power outlet is like applying an external electrical field to the wire (or adding pressure at one end.)

As stated before, while the speed of the transmission of the electrical current itself is about the speed of light, the actual electrons within that wave might only move along at a few millimeters per second. This is because the electrons themselves are bouncing around the conductor and creating the energy that is released in the wave, but are not necessarily moving along with it.

This means that in the case of an alternating current, where the current changes direction 50 or 60 times per second, most of the electrons never make it out of the wire.6 But electricity itself is still flowing thanks to the electrons’ excitement. 

Solar Panels and Speed of Electricity

When solar panels generate electricity, they do so with a direct current (DC). You could think of a DC current as raw, as it only flows in one direction. Solar panels generate DC due to the nature of their silicon and electronic conductors. 

Sunlight excites the free electrons in the silicon wafers (or thin film components) inside solar panels. This moving of the electrons up to a higher level of energy creates a direct current of electricity—but without a conductor, that energy would just sit there. 

A network of wires connects the solar panel power-generating components to where the DC current can be converted into an AC current that’s used to power the home. This is a device known as a solar inverter. 

There are different kinds of solar inverters; some are located in a central place while others, known as micro-inverters, are small and are a part of the solar panel itself. Either way, the goal of a solar inverter is to change the DC current into an AC current for your home to use. 

The wiring and outlets on your house use alternating current (AC), which change direction periodically. AC power is used to power homes and offices because it is relatively easy and safe to transport and distribute across long distances.

AC can also be converted from and to higher and lower voltages based on power needs. This is done with transformers.7

Since solar panels don’t store energy, you’ll either use the AC power right away to power your home electronics and appliances, or send any power generated back to the power grid. Depending on where you live, you might be eligible for different kinds of net metering or other credits for supplying clean energy to the grid. 

If you also have a solar battery backup, the power will be converted back into DC power for storage. Most batteries store and produce DC power. 

Then, when you’re ready to pull from the battery energy bank, you can be sure the electricity will flow freely and just about at the speed of light.

 

Endnotes

1 https://www.space.com/15830-light-speed.html
2
 https://www.ck12.org/physics/electromagnetic-waves/lesson/Properties-of-Electromagnetic-Waves-MS-PS/

3 https://www.electronics-notes.com/articles/basic_concepts/current/what-is-electrical-current.php
4 https://www.electronics-notes.com/articles/basic_concepts/current/what-is-electrical-current.php
5
 https://www.electronics-notes.com/articles/basic_concepts/current/what-is-electrical-current.php

6 https://www.livescience.com/53889-electric-current.html
7 https://learn.sparkfun.com/tutorials/alternating-current-ac-vs-direct-current-dc/all

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