What is a pure sine wave inverter?

By Matthew Joseph Nandirio •  Updated: 10/08/22 •  6 min read

If you are using solar panels to power up your home you will definitely need an inverter to convert the power from the solar panels which are DC power to usable AC power. You will find basically three types of inverters in the market: pure sine wave inverters, modified sine wave inverters and square wave inverters. When you get to know the difference, you will know to choose the best for you.

What is a pure sine wave inverter?

A pure sine wave inverter transforms direct current (DC) into usable alternating current (AC), which has a smooth and constant voltage. They precisely replicate the form of the AC waveform you obtain from local power suppliers enabling them to operate any 240V AC-powered device.

How Does a Pure Sine Wave Inverter Work?

In a pure sine wave inverter, the conversion of DC to AC happens in 3 steps:

  1. Creating Oscillating Pulses

The inverter creates oscillating direct current pulses that simulate positive and negative polarity peaks using integrated electronics. These pulses must be amplified since they are very weak.

  1.  Amplifying the Signal

To power appliances, this stage amplifies the 12V or 24V pulses to high current levels. The output voltage is still too low to operate any device even if it is already in AC form.

  1.  Raising the Output Voltage

A magnetic transformer is employed in the final step of the DC/AC conversion to boost the voltage to 110V or 120V, that’s what your appliances require. These AC voltage sine waves are not real sine waves in their raw form; instead, they are jagged and boxy. To make the alternating current smoother, pure wave sine inverters use extra capacitors and filters.

Advantages And Disadvantages of Pure Sine Wave Inverter

To select the best inverter for your home you might want to know their good and bad features of them as below.

Smooth Output Voltage\ Stable PowerExpensive
Minimal Risk to Devicesweight
Quieter OperationShorter battery run
Compatible with a wide range of equipmentPower Usage

Advantages of Pure Sine Wave Inverters

  • Smooth Output Voltage

A pure sine wave inverter eliminates choppy drops and surges providing smooth output voltage. They also produce stable power with low harmonic distortion. This makes it possible for your delicate electronics to function without glitches, crashes, or other unexpected interruptions. 

  • Minimal Risk to Devices

During sudden power outages, your high-end devices are prevented by the smooth waveform a pure sine wave inverter creates. Additionally, utilizing modified sine wave inverters with appliances that have AC motors, including refrigerators and microwaves, can result in too much waste heat, endangering your appliances. But pure sine wave inverters pose no risk to any of your equipment.

  • Quieter Operation

Pure sine waves steadily adjust their phase angle and polarity with no abrupt drops as the voltage increases and decreases. This lessens the annoying electrical noise made by appliances such as fluorescent lights, TVs, and audio amplifiers.

  • Compatible with a wide range of equipment 

The properties of pure sine waves are identical to those of grid voltage. They can thus use power more efficiently and are ideal for devices with AC motors.

A pure wave inverter is more than enough to power your PC, so there’s no need to spend money on a separate UPS for it.

Disadvantages of Pure Sine Wave Inverters

  • Expensive

Due to the advanced and sophisticated technological requirements, they use high-end electronic components. So the price of a pure sine wave inverter will be always higher than other types of inverters.

Pure sine wave inverters are so effective that they will save your energy and will reduce the harm to your appliances. Worth the cost!

  • Weight

Because the PSW inverter contains a large, inefficient transformer, it is typically heavier than Modified Sine Wave inverters.

  • Shorter battery runs

The pure Sine wave inverters use sophisticated technology built into their circuits resulting in reduced battery running times. Pure Sinewave inverters also use heavy, ineffective transformers that reduce battery runtime.

  • Power Usage

Compared to Pure Sine Wave inverters, Modified Sine Wave inverters are more cost-effective. In general, pure sine wave inverters are less efficient at using DC power than modified sine wave inverters, therefore your battery will deplete more quickly.

When do we need a pure sine wave inverter?

You will need a pure sine wave inverter if you have sensitive electronic devices with you. Electronics that utilize AC motors, such as refrigerators, compressors, and microwave ovens, are the equipment that operates more effectively if you are using a pure sine wave inverter.

Other than those you definitely will need a pure sine wave inverter if you are going to use these things in your home.

  • Devices with thyristors – Laser printers, Photocopiers, Domestic light dimmers
  • Devices with silicon-controlled rectifier (SCR) – Washing machines, Welding machines 
  • Magneto-optical hard drives
  • The built-in clocks in devices – Microwave Ovens, Alarm clocks

These devices get their timing from the peak of the line power.

  • Light fixtures that have power factor correction capacitors
  • Transformer-less capacitive input-powered devices
  • LED TVs

You generally don’t need a pure sine wave inverter if your electronic equipment converts AC to DC using rectifiers. Definitely, those pieces of equipment work fine with pure sine wave inverters.  But a modified sine wave inverter which is cheaper will also do the work. 

 When your purchase an inverter do check the followings with your requirements

Pure sine wave inverterModified sine wave inverter
Efficiency
Price
Quality of current
Compatibility with all appliances 

How to pick your inverter?

If you wish to go with the local power suppliers or any power backups you will probably need a pure sine wave inverter. They include a built-in charger that automatically stores energy in a battery bank Once connected to external power. However, your intended use will determine which sine wave inverter is ideal for you. You will find inverters from a few hundred dollars to thousands of dollars. Since almost all equipment works with pure sine wave inverters it is your budget that decides the best inverter.

Out of all inverters, if you are going to use a pure sine wave inverter, you will experience the risk-free running of your equipment. It will cost more, but it is effective.

References

  1. PURE SINEWAVE INVERTER OWNER’S MANUAL Switch Mode Pure Sinewave Inverter. (n.d.).
  2. Doucet, J., Eggleston, D., Institute, J. S.-P. W. P., & 2007, undefined. (n.d.). DC/AC pure sine wave inverter. Wpi.Edu. Retrieved September 18, 2022, from https://web.wpi.edu/Pubs/E-project/Available/E-project-042507-092653/unrestricted/MQP_D_1_2.pdf
  3. https://www.youtube.com/watch?v=qVeERT4nyz8
  4. Introduction to Photovoltaic System Design – John R. Balfour, Michael Shaw – Google Books. (n.d.). Retrieved September 19, 2022, from https://books.google.lk/books?id=kN1x4Rnv64kC&pg=PA170&dq=types+of+sine+wave+inverter&hl=en&sa=X&ved=2ahUKEwjj6uOKsKH6AhWZRWwGHRGtC-AQ6AF6BAgIEAI#v=onepage&q=types%20of%20sine%20wave%20inverter&f=false
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Matthew Joseph Nandirio

Matthew Joseph Nandirio is the Founder of walkingsolar. After graduating from the University of Houston in 2002, matt started working as an electrical and electronic engineer for several multi-national solar energy companies. He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research. He now shares his 20 years of expertise through his articles on the walkingsolar website. Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.

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