When it comes to electricity there are two different flavors.
- DC – Direct Current where electrons flow in one direction only.
- AC – Alternating Current where electrons periodically reverse direction.
Solar cells produce DC energy where most household appliances require AC energy.
Consequently, solar cells must use an inverter to convert the DC power they produce into the AC power that your house requires.
Why Do Solar Cells Produce DC Power?
Solar cells are a rather ingenious bit of engineering. Because of their design and the materials used in their manufacturing, the potential for electron flow is always present. All that is needed is the bombardment of photons, found naturally in sunlight, and electrons are knocked into motion.
This motion is guided by means of small wiring cleverly laced throughout the solar cell.
It is this wiring that channels the movement of electrons so that all electron flow ends up moving in one direction, thus producing Direct Current electricity.
To visualize this, consider a tea kettle.
Sitting on the stove, filled with cool water, there is very little in the way of electron movement. However, once heat is applied, electron movement increases until a steady stream of steam is exiting directly through the nozzle.
It is essentially the same concept for DC in solar cells. The more photons that are applied, via sunlight, the more internal electrons are knocked into a ‘excited state’. This energy is provided an outlet, via wiring, much like the tea kettle has a nozzle for steam to escape.
For an in-depth look at this, please read, “How Do Solar Panels Work?”
Could Solar Cells Produce AC Power?
Designing a solar cell that would produce AC would be quite challenging. As in the tea kettle example mentioned above, try imagining the escaping steam stopping and then returning back in. Not only would the established motion have to be stalled and then reversed, but the potential pushing this motion is still present – caused by the continuation of bombarding photons (sunlight).
Also, AC power is most often produced with the help of magnetic fields. It is uncertain how electron flow would react to a magnetic field given the design and makeup of a solar cell and how this magnetic field would have to be constantly managed due to fluctuating photon bombardment.
In other words, things would have to be adjusted to every slightest cloud that alters the amount of sunlight coming in contact with the solar cell at any given moment.
Why Do Houses Use AC?
Originally, things were powered by DC. But all that changed during the War of the Currents that occurred in the 1880’s and 1890’s.
With Thomas Edison pushing for DC and George Westinghouse pushing for AC, the stakes could not have been higher as the entire planet would embrace the winner.
It is the motivation behind the movie, The Current War.
In the end, Alternating Current became the power of choice, but…
Virtually every electronic device today, be it a smart TV or handheld, uses Direct Current. This means that AC has be converted to DC in order for your electronic device to work.
In other words, for those who do have solar panels, the DC power that is generated by your solar cells is converted to AC, only to then be converted back to DC for your electronic device.
How ironic is that?!