Apparently, we meet them every day, but if physics lessons in school are left behind, these concepts don’t necessarily tell us much. We know they are related to electricity, the capacity of a phone battery or a power bank, but due to the noise of the information, we rarely bother to check absolutely everything we find.

## Volt per watt, ampere, ampere hour and kilowatt hour, that is, explain the basics

However, when we talk about photovoltaic energy, these terms are necessary. Without them, it is impossible to understand everything exactly as we should. So, let’s explain **what a volt is, how it differs from a watt,** and what lies behind the other values.

## What is Volt, WAT, Joule, etc.?

### VOLT

symbol: **V.**

A volt is a unit of electric potential, electric voltage, and electromotive force. It is a unit of the SI system. A volt is a watt divided by an ampere. How else can this concept be expressed differently? This is 1J (Joule) work done while changing a 1C (coulomb) electrical charge from one point to another.

### WATT

symbol: **W.**

A watt is a unit of energy power that is also part of the SI system. Its name comes from the name of the British inventor and engineer James Watt. One W is the power to which one second of work equals one joule. In photovoltaic power, it works on a multiple of a watt, most often kilowatts (kW), with a kilowatt being, of course, a thousand watts.

### JOULE

symbol: **J**

One joule is the SI unit of work, energy, and heat. Its name also comes from the name of the scientist, the English physicist James Joule. One joule is the work done by a force of one newton in displacing the point of application of the force by one meter.

### AMP

symbol: **A**

It is a unit of electrical current. As above, it is part of the SI system. An ampere is the designation that tells us that there is one coulomb of charge in one second.

### AMPER HOUR

symbol: **Ah**

Amp-hour is a measure of capacity used for galvanic cells, including but not limited to electric batteries, including the aforementioned power banks. What does this tell us? What is the capacity of a given battery to power an electrical circuit with a given amperage for a given period of time? One amp-hour is responsible for the flow of 3,600 coulombs per hour.

### KILOWATT-HOUR

symbol: **kWh**

A kilowatt hour, such as a joule, is a unit of work, energy, and heat in the SI system. A kilowatt hour is the amount of energy that a 1000 watt (one kilowatt) device will use in one hour. What is your relationship to the joule mentioned above? One joule is a watt-second and a kilowatt-hour is its multiple. This is the unit that we will find most often when we talk about photovoltaic panels, since it is used to indicate the amount of energy that a certain installation produces.

## Photovoltaic micro installation up to 50kW: what does it mean?

We often come across information on photovoltaic micro-installations up to 50kW, so we now know that it is an installation that can produce up to 50 kilowatts. That’s a lot? If we have a single-family home and we think about photovoltaics, the **demand** usually **oscillates between 10 and 15 kilowatts** . Of course, it all depends on many factors. For some people they have little equipment at home, while others build modern houses in which everything is combined in a single electronic organism.

In order to correctly calculate the demand, we must take into account all the electrical appliances that we have installed at home or that we plan to buy. It is worth bearing in mind that the devices that will have the highest instantaneous power consumption include an electric stove, heaters, and underfloor heating. Certainly, when calculating the overall potential, it is also worth adding a possible margin of error. The best way is rounding. We never know what the situation will be like in a few years.

## What else is worth remembering?

It is worth being aware of what we read, being able to decode symbols, remembering knowledge of physics. However, we don’t have to worry about any calculations regarding photovoltaics. The specialists will do it for us. First of all, they will calculate the connection power that we will need, as well as the number of panels, they will design the structure so that the panels work as efficiently as possible. Therefore, if we plan to collaborate with a company that is dedicated to the supply of photovoltaic installations, we can be sure of the shape and structural safety.

However, any talk is definitely worth preparing for. Then we will make sure that the topic we are discussing is familiar to us. We can more easily ask relevant questions and understand the answers to them. However, if it happens that we forget something or something is not clear to us, qualified employees will explain everything to us.