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How To Distinguish Between Pure and Modified Sine Wave Units

Rows of solar panel inverters on a roof

Businesses that deal with uninterruptible power supplies and solar inverters may be familiar with pure and modified sine wave units. These are types of waveforms used to describe the output of power inverters, and buyers must know the differences when choosing the right equipment for their needs.

This article covers how solar inverters work, what pure and modified sine wave units are, their advantages and disadvantages, and their differences to help brands make informed purchasing decisions.

Table of Contents
Overview of the solar inverter market
How do solar inverters work?
What are pure sine wave inverters?
What are modified sine wave inverters?
How to detect a pure or modified sine wave inverter
Rounding up

Overview of the solar inverter market

Market statistics

According to statistics, the global solar photovoltaic inverter market was worth US$ 7.7 billion in 2020 and is anticipated to reach US$ 17.9 billion by 2030, growing at a compound annual growth rate (CAGR) of 8.8% from 2021-2030.

Market drivers

The major drivers of the market are fast growth in the clean and renewable energy sector and the easy installation of solar inverters in homes and buildings. However, problems like high costs, heat loss, and lack of proper monitoring and maintenance threaten to restrain future market growth.

Nevertheless, government investments and initiatives in electrifying rural and remote areas will likely create market expansion opportunities. Moreover, there’s a significant relief from the market decline caused by the COVID-19 pandemic due to suspended construction and industrial activities.

Product type

The central inverter segment topped with an estimated market share of 50.9% in 2020. Given the rising demand for central inverters in large industrial and utilities applications worldwide, it is foreseen to maintain its lead.

Moreover, developing economies like China and India are undergoing rapid industrialization, which is expected to boost demand during the forecasted period.

End users

The utility segment dominates the market by revenue share and is anticipated to grow at a CAGR of 8.3%. Higher investments and new construction projects such as decentralized solar power plants and rural electrification boost the sector’s growth globally.


Asia-Pacific had the highest share in 2020 and is projected to continue leading during the forecast period. The presence of multiple key players and a large consumer base in this region are the primary drivers of the market.

Furthermore, technological advancements and huge investments will likely expand the renewable energy sector. And refurbishing old power infrastructure will fuel exciting market growth in the coming years.

How do solar inverters work?

Solar inverters are connected to solar panels, which trap sunlight and turn it into energy. This energy is sent to the inverters, which convert the direct current (DC) generated by solar panels into alternating current (AC) for electrical power devices in homes and businesses.

The inverters must change the constant DC voltage to a sine wave cursive above and below 0 volts. The inverter tracks and adjusts the voltage of the solar panels to ensure they are operating at maximum efficiency.

Next, the AC output is synchronized with the electricity grid so that the generated electricity can be used locally or distributed back to the grid for storage. Users may plug in appliances after the conversion.

Solar inverters have built-in safety features that shut the system automatically in an emergency or power outage. They also have monitors that enable consumers to track the system’s performance and energy production.

What are pure sine wave inverters?

A pure sine wave inverter converts DC to AC in a waveform that is similar to a standard grid-supplied AC power. Pure sine wave power moves in uniform waves and flows very smoothly.

Hence, they are suitable for powering electrical appliances, including sensitive electronic devices like laptops, LED TVs, medical equipment, and inductive loads like brushless motors.


Pure sine wave units are compatible with a wide range of electronic devices, especially sensitive ones that require a stable and high-quality power supply. In addition, they are generally more efficient, thus resulting in lower operating costs and increased equipment life span.

Most consumer electronics are manufactured for a pure sine wave power operation. Some electrical appliances such as audio equipment, motors, microwave ovens, and anything with a thyristor will only run properly using pure sine wave inverters.

Moreover, it produces less noise and interference, which enhances performance thanks to its uniform amplitude.


Due to their close resemblance with conventional electricity grid supplies, these inverters are more complex and expensive to produce, making them less attractive to consumers.

On top of this, due to their heavy weight, pure sine wave inverters are also often arduous and burdensome to transport and install. In addition, they can lead to more standby power consumption, which results in higher operating costs.

What are modified sine wave inverters?

The first set of inverters was designed to create blocky signals that make the voltage go straight up and down like a staircase. These types of inverters are known as modified sine wave inverters. They convert DC to AC with a waveform that is not as smooth as a pure sine wave inverter.

Modified sine wave inverters are appropriate for charging basic electronics and less sensitive appliances like phone chargers, heaters, and air conditioners. However, it can still power many devices except those with thyristors, electronic timers, and digital clocks.

This equipment gets its timing from the wave peak, which a modified sine wave does not possess since it has a flat top rather than a peak.


Unlike pure sine waves, modified sine wave inverters are lightweight and easy to transport and install. They are also cheaper, making them excellent options for consumers on a budget.

Furthermore, thanks to their compactness, these inverters can provide high surge power, which is suitable for powering high-current start-up devices like refrigerators.


As stated earlier, modified sine wave units are less efficient and are incompatible with certain devices. As a result, medical equipment, audio equipment, and specific computers may not function properly on this power source. In addition, it can shorten their lifespan or even damage the devices.

Again, their nonuniform wave patterns produce more noise and interference, similar to a buzzing sound heard in refrigerators and ceiling fans.

How to detect a pure or modified sine wave inverter

Check the cost and efficiency

Pure sine wave inverters are more expensive and can power sensitive appliances without risk of damage or noise.

On the other hand, modified sine wave variants have distortions and lower efficiency. Appliances plugged into these inverters use up to 30% more power than adequate, and hence are unable to run at total capacity. Over time, this can lead to excess heat that may damage the equipment.

You can compare a pure sine wave unit to a car on wheels while modified sine wave units to one on octagonal or even square wheels. The latter will have a rough ride and may not even survive if the vehicle’s components are sensitive.

However, since they are simpler to produce (with fewer components), modified sine wave units are inexpensive and budget-friendly.

Labels are also good indicators

Sometimes, manufacturers may put labels explicitly stating if an inverter is a pure or modified sine wave inverter. For example, a label with the term “quasi sine wave” or “modified square wave” may describe a modified sine wave inverter.

However, it is not a reliable indicator as different manufacturers may use different terminologies.

Examine the interference

This method is the most reliable way to determine the waveform of an inverter. The examination uses an oscilloscope or a waveform analyzer by connecting it to a load and measuring the voltage output.

This output can be compared to a reference waveform to determine the distortion. If it is a smooth continuous waveform, it is a pure sine wave unit. On the contrary, a stepped or stair-like appearance signifies a modified sine wave inverter.

A multimeter or power analyzer can also measure power quality and efficiency, as a pure sine wave will produce cleaner, high-quality power than a modified sine wave inverter.

It is important to note that electrical noise from other equipment or poor wiring can affect the waveform output of an inverter. Therefore, it is advised to perform multiple tests to confirm the type accurately.

Check the proven track records

Another way to differentiate between pure and modified sine wave inverters is to check the proven track records. Brands should be open to revealing their product’s track record, so consumers must avoid anyone that refuses to provide it.

For pure sine wave inverters, the track records should show the device utilized in homes, offices, and other establishments requiring an adequate power supply. It should also show the inverters handling sensitive appliances and devices, like TVs and refrigerators.

On the other hand, modified sine wave inverters should have track records showing their effectiveness for regular home and outdoor use. Since they’re not as powerful as their pure counterparts, they will only handle lights and other basic equipment.

Rounding up

Both solar inverter units have advantages and disadvantages, so choosing the right one depends on the power requirements, budget, and device specifications.

The more complicated and sensitive the devices are, the greater the likelihood of needing a pure sine wave inverter. Alternatively, if the power demand is simple, a modified sine wave might be a better option as it is lighter and more cost-effective.

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