Need Help? Call us 087 896 3069  send us an Email:

Modified Sine Wave Inverters vs Pure Sine Wave inverters

Table of Contents

Which is better: modified sine wave vs pure sine wave inverter?

The main difference between pure and modified sine-wave inverters are efficiency and cost. Pure sine wave inverters are known for their efficiency when powering devices that use AC, as well as their ability to power devices like radios without causing interference. However, they can be quite expensive.

In contrast, modified sine-wave inverters are less expensive, but they may produce some interference, resulting in a less pure current. In other words, pure sine-wave inverters are a better choice if you need clean, efficient power, but they come with a higher price tag. Modified sine-wave inverters are a more affordable option, but they may not perform as well in certain situations.

Choosing the right type of solar inverter

If you’re not sure which type of inverter is best for your needs, here are some questions you can ask yourself to help you decide:

  1. Does my device or appliance use a motor?
  2. Is my device a delicate piece of medical equipment?
  3. Does my device or appliance use a rectifier?
  4. Can my device be powered by a DC adapter?

If you answered yes to the first two questions, you may need a pure sine-wave inverter to ensure that your devices run smoothly and without interference. If you answered yes to the second two questions, then a modified sine-wave inverter may be sufficient. However, if you’re not sure whether your appliances can run on a modified sine wave, it’s always best to check with the manufacturer of the appliance you are trying to power.

What is a solar power inverter?

Inverters play a crucial role in photovoltaic systems by converting the direct current (DC) output from your solar panel into the alternating current (AC) that is used by most appliances. In other words, inverters act as a bridge between your solar panels and the devices that use the electricity generated by your system. By transforming the DC output into AC, inverters make it possible for you to use the energy produced by your solar panels to power your home or business.

Why do I need an inverter for my solar installation?

Solar inverters are a vital part of any solar installation. Most appliances in your home run on alternating current (AC), so the direct current (DC) electricity produced by your solar panels needs to be converted before it can be used. That’s where inverters come in. They take the DC power from your panels and transform it into AC power, which is then sent to your appliances. Inverters also adjust the voltage to ensure that your devices receive the right amount of power.

Screenshot 2022 11 10 at 11.12.00

What is a pure sine wave inverter?

A pure sine wave inverter is a type of electronic device that converts direct current (DC) into alternating current (AC). It does this by converting the DC input into a pure sine wave output. This is important for many applications because a pure sine wave is necessary for accurate power conversion and to prevent damage to sensitive electronics. Pure sine wave inverters are known for their ability to produce a clean and consistent power supply, making them ideal for use in a wide range of applications.

What is a modified sine wave inverter?

A modified sine wave inverter is a type of inverter that converts direct current (DC) into alternating current (AC), but the AC power it produces is not a perfect sine wave. Instead, the polarity of the output abruptly switches from positive to negative, resulting in a waveform that has a stair-step or square pattern. Also, sometimes referred to as a square wave inverter.

This choppy waveform can be harmful to delicate and sensitive equipment, so it is not suitable for powering medical devices like CPAP machines. Modified sine wave inverters may also produce a hum when used with certain devices. In general, pure sine wave inverters are considered to be superior to modified sine wave inverters because they produce a cleaner and more consistent power supply, and they are less likely to cause damage to electronic equipment.

What can I run with a modified sine wave inverter?

Modified sine wave inverters can be used in simple systems that don’t have sensitive electronics. If your system doesn’t have an AC motor and doesn’t include delicate medical equipment, then a modified sine wave inverter may be sufficient. Older TVs, water pumps, and phone chargers are generally able to run on a modified sine wave inverter without any problems.

However, appliances like refrigerators, microwaves, and compressors that use AC motors will not run as efficiently on a modified sine wave inverter. Some fluorescent lights may also not be as bright and may produce a buzzing or humming noise when used with a modified sine wave inverter. If you have any of these types of devices, you may want to consider using a pure sine wave inverter instead.

What are the pros and cons of using a modified sine wave inverter?

One of the main advantages of using a modified sine wave inverter is that it is typically less expensive upfront than a pure sine wave inverter. Modified sine wave inverters typically cost between R1,000 and R10,000 while pure sine wave inverters can cost between R3,000 and R40,000.

However, there are also some drawbacks to using a modified sine wave inverter. One of the main disadvantages is that they are less efficient than pure sine wave inverters. This means that motors, such as those found in refrigerators, pumps, and fans, will use more power from the inverter and will be less efficient overall. Most motors will use about 20% more power when run on a modified sine wave inverter, which can cause them to run hotter and not last as long. This can be a significant disadvantage if you have a lot of motor-driven appliances in your home or business.

What size inverter do I need?

The size of the pure sine wave or modified sine inverter depends on your electrical appliance requirements. Each solar inverter has its own set of unique capabilities. Remember, the fancier & bigger the inverter the bigger the price tag.

When choosing an inverter, you should consider the type and amount of load you will be running. This will help you determine whether you need a standard inverter or a more powerful model to handle your power usage.

The size of the inverter you need is determined by the total power requirements of all the devices you want to power. You can calculate this by adding up the power needs of each individual device. It’s important to distinguish between essential devices and appliances that have low or high power requirements, such as stoves, pumps, water heaters, and kettles.

You can also compare the capacity of your backup power system to the total amount of power you need to run all your devices during a power outage. This will help you determine whether your inverter is powerful enough to keep your devices running during load shedding.

Example: You want to power a computer with a 17″ monitor, some lights, and a radio.

Computer300 Watts
2 – 60 Watt Lights120 Watts
Radio10 Watts
Total Need430 Watts per hour or 0,43kw per hour

Based on the above calculation, a 1KW/1000W Hybrid inverter will be more than enough to power your appliances. The average household makes use of a 5 or 8-kw inverter that is capable of powering 90% of all the appliances in the house.

If you need to convert amps to kilowatts you can make use of the following amp-to-kilowatts calculator

Can I use a modified sine wave inverter with an off-grid system?

If you are using an off-grid solar system, you can use a modified sine wave inverter to power your simple appliances. However, if you are connected to the grid, you will need a pure sine wave inverter because utilities provide energy in the form of pure sine waves.

In general, pure sine wave inverters are recommended for use with grid-connected systems because they are more efficient and can prevent damage to electronic equipment. Modified sine wave inverters are a more affordable option, but they may not be suitable for all applications.

So do I buy the modified sine inverter or pure sine wave inverter?

Pure sine-wave inverters used to be a luxury item that was out of reach for many consumers due to their high cost. However, as the price of pure sine-wave inverters has come down, they have become more accessible to the average person. Modified sine-wave inverters are still a good option if you only need to power a few simple appliances and don’t mind sacrificing some efficiency. However, if you want the assurance that your appliances and devices will run safely and at their highest efficiency, we recommend investing in a pure sine-wave inverter.

off grid power solutions - talk to an expert

Share this post
About the author
Picture of Off Grid Power Solutions

Off Grid Power Solutions

Our team brings over 25 years of expertise in the renewable and power industry as an established online solar supplier.

Shop Our Products


Fill in the form below and our team will be happy to assist you