Meaning, Functions and Power Ratings of Inverters for JSS 1

Inverters

Performance Objectives

By the end of the lesson, students should be able to:

1. describe inverters;
2. list the functions of inverter;
3. read Inverter power rating from the inverter name plate.

Introduction to Inverters

In many homes and businesses in Nigeria, solar panels are used to generate electricity. Solar panels produce a type of electricity called Direct Current (DC). However, most common household appliances, like televisions, fans, and refrigerators, use a different type of electricity called Alternating Current (AC).

To use the electricity from solar panels to power these everyday appliances, there needs to be a special device that changes DC electricity into AC electricity. This important device is called an inverter.

Meaning of Inverters

An inverter is an electronic device that converts direct current (DC) electricity into alternating current (AC) electricity.

Direct current (DC) flows in one direction, like the power from a battery or a solar panel. Alternating current (AC) changes direction many times per second, which is the type of electricity supplied by the national grid and used by most home appliances.

Functions of Inverters

The main function of an inverter in a solar power system is to change the type of electricity so that it can be used by common appliances. Without an inverter, the DC electricity from solar panels or batteries cannot directly power most devices in a home or office.

The key functions of an inverter include:

1. Converting DC to AC Power: This is the primary role of an inverter. It takes the DC power generated by solar panels or stored in batteries and transforms it into AC power.
2. Powering Household Appliances: By converting DC to AC, the inverter makes it possible for appliances like televisions, fans, lights, and refrigerators to run on solar energy.
3. Providing Backup Power: When connected to batteries, inverters can draw stored DC power from the batteries and convert it to AC, providing electricity to the home during power outages or at night when solar panels are not generating power.

Power Ratings of Inverters

Every inverter has a power rating, which tells us how much electrical power it can supply to appliances at one time. This rating is very important because it determines how many and what kind of appliances an inverter can power without being overloaded.

Inverter power ratings are usually measured in units like Watts (W), Volt-Amperes (VA), or kiloVolt-Amperes (kVA). For JSS1, we will focus on understanding that these numbers tell us the inverter’s capacity.

1. Watts (W): This is a common unit for measuring real power. It tells you the actual power an inverter can deliver to run appliances.
2. Volt-Amperes (VA): This unit measures apparent power. It is often used for the total power an inverter can handle, including both real power and reactive power. For simple understanding, a higher VA rating means the inverter can handle more load.
3. kiloVolt-Amperes (kVA): This is simply 1000 VA. So, an inverter rated 1 kVA can supply 1000 VA of power.

When choosing an inverter, it is important to ensure its power rating is high enough to meet the total power needs of all the appliances that will be connected to it. If the total power required by the appliances is more than the inverter’s rating, the inverter can get damaged or shut down.

Reading Inverter Power Rating from the Nameplate

Every inverter has a nameplate, which is a label or sticker usually found on the body of the inverter. This nameplate contains important information about the inverter, including its model number, serial number, voltage, and most importantly, its power rating.

To read the inverter power rating from the nameplate, follow these steps:

1. Locate the Nameplate: Find the sticker or metal plate attached to the inverter. It is usually on the side, front, or back of the device.
2. Identify the Power Rating Section: Look for terms like “Output Power,” “Rated Power,” “Capacity,” “VA,” “kVA,” or “Watts (W).” These terms indicate the power rating.
3. Read the Value: Note the number written next to these terms. For example, you might see “2.5 kVA,” “2500 VA,” or “2000 W.” This number is the inverter’s power rating.

Observe the image below, which shows an example of an inverter nameplate. The power rating is highlighted.

For example, if a nameplate shows “Rated Power: 2.5 kVA,” it means the inverter can supply 2.5 kiloVolt-Amperes of power. This information helps users understand what appliances can be safely connected to the inverter.