Alternating Current vs. Direct Current
Alternating Current vs. Direct Current

Alternating Current vs. Direct Current

I will unmask one of the terms I usually discuss pretty frequently. I am talking about the differences between direct and alternating current.

It does not matter if we are users of a photovoltaic installation connected to the grid or isolated; the importance of the current is vital for the correct functioning of the photovoltaic process. 

However, what differences do we find between direct and alternating current? What examples can we find to understand each type better? Discover these secrets and more in the following questions.

What is direct current?

So that you understand it first, direct current is when the electrons that circulate inside a cable do so in a single direction. This may have other forms of expression, such as direct current or abbreviations, such as DC or CC. If you find these terms somewhere, you already know you are looking at a single-path circuit. 

The direct current system is attributed to the famous Thomas Edison. He discovered the possibility of generating electric current through a conductive metallic material, which attracts electrons through one pole and repels them through the other (positive or negative). In this way, being in a closed circuit, the explanation comes from the only direction of the electrons. 

Some elements that generate direct current artificially are batteries or photovoltaic solar panels. As a curiosity, there are natural phenomena that also generate direct currents. I am referring to lightning, which goes in only one direction: Cloud to ground. 

What does alternating current mean?

As I said, the electrons went in a single direction in direct current. When we talk about alternating current, it is ultimately the opposite. The electricity that circulates through these systems can take several directions. Its objective is to transport more energy over a greater distance, which is the basis of energy transportation and distribution networks.

The flow of electrons creates a wave in two directions, one above the T line and the other below. Each time an electron passes through these two phases, it is called a frequency. This is measured by Hertz, a unit that defines cycles per second. With this, an alternating current of 60 hertz will perform that number of cycles in a single second. 

The discoverer of alternating current was the scientist Nikola Tesla. Today, this type of current comes out through our home or business sockets. Let us remember that it is transported by the tall electricity poles that we see on the roads that come, in turn, from the electricity generation plants.

What are the differences between direct and alternating current?

Looking at both concepts more theoretically, let’s look at the most notable differences between direct and alternating current. I have already given some strokes throughout the entry, but let’s go deeper in a more schematic way. Let’s go there!

1. Total energy transported: In direct current, the energy transported is limited to the transport capacity of the element used (batteries, batteries, etc.). On the other hand, in alternation, the limit is set by who generates that energy.

2. Connection: In DC, it is essential to connect each pole with its opposite so that there is a current, but if we talk about alternating current, things change. No matter where we connect a device, it allows its connection (home outlets).

3. The direction of current: Direct current has only one direction. Alternating current is like taking one step forward and one step back. This is because the source that generates that current does not always have the same intensity. Therefore, it is constantly changing.

4. Voltage used: The voltage will always be the same in direct current. On the other hand, alternating current may vary depending on where you are. Generally, the voltage is lowered before reaching a city so there are no surges or power outages through transformers. 

5. Storage: The energy transported by direct current can be stored in photovoltaic systems with batteries. On the other hand, alternating current does not have this option, so what is consumed will always be used. 

What examples do we find of direct and alternating current?

We already know everything we need about the differences between direct and alternating current, but we must give an example. Both types are prevalent, although they have different uses. Be careful because some may surprise you. 

1. Direct current: It is usually used in electric vehicle batteries, all devices with a battery, and to charge computers. The latter has a central box in the charger that converts AC to DC.

2. Alternating current: Distributes the generated energy efficiently through the transportation and distribution network. It is the one that reaches our homes or companies and from which we rely to turn on electrical devices. The majority of energy used is the latter. 

What symbols do direct and alternating current have?

As many users are unaware of the differences between direct and alternating current, two published symbols distinguish both concepts. You will find these in the back of electronic equipment, batteries, cells, and everything that needs electrical energy.

The symbols for direct and alternating currents differ in the wave that describes them. While in DC, we see a straight line that indicates the only direction of the electrons, the symbology of AC is described with a sine wave. Generally, this type of wave makes an oscillatory movement concerning a point.

Does a photovoltaic installation use direct or alternating current?

Photovoltaic installations combine direct and alternating current. In the first process, the energy received by the solar panels and transferred is in direct current until it reaches the inverter. This element is responsible for transforming this type of current into an alternating current to deliver that energy to all the sockets in our house. 

The direct-to-alternating current inverter is essential in all photovoltaic installations. Without it, it couldn’t function. Remember that, depending on our electrical installation, these can be single-phase or three-phase. If you do not know this information, you can ask a professional by sending us your last electricity bill. 


Within the energy and electrical sector, knowing in depth the differences between direct and alternating current is essential to understand everything that happens within it. 

As I have seen, the main difference between both terms lies in the direction of the electrons that circulate inside the circuit. When I talk about DC, they do it in one direction, and AC in several directions. 

The differences do not end there since storage, connection, transported energy, or voltage issues must be considered when discussing direct and alternating current. 

Needless to say, they are essential for solar self-consumption, where, thanks to the power inverter, we can enjoy clean and 100% renewable energy. 

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