By: Chris Gardner, Western Region Sales

The electric grid wasn’t built for the complexity of today’s energy environment.  From rooftop solar and EV chargers to an explosion of non-linear electrical loads, power flows through distribution networks have fundamentally changed. These changes come with power quality challenges. One quality measure of increasing concern is harmonic distortion.

In simple terms, harmonics are a distortion of the 60 Hz waveform and they occur as multiples of the original sine wave. They’re introduced by fast-switching electronics: DC power adaptors, HVAC (and other VFD) systems and office equipment. Instead of drawing electricity in a smooth curve, these devices pull current in rapid pulses, sending ripples across the grid in the form of harmonic distortion.

The growth of these distortions will increase by at least 3X in 2034 (using AC-DC Adaptor market as a proxy). Their impact will be consequential.

Harmonics can:

• Overheat transformers and neutral wiring
• Shorten asset life through insulation degradation
• Cause sensitive equipment to misfire or fail
• Lead to flickering lights, faulty metering and energy loss
• Create cascading issues on feeders and in substations

The most problematic harmonics are often low-order frequencies, such as the 5th (300 Hz) and 7th (420 Hz), which are both common and especially damaging. They don’t travel far, but they hit hard, typically at the transformer or service point, where DERs and variable loads connect to the network.

The traditional approach to identifying harmonics is as inefficient as it is expensive: send a truck to install a power quality monitor, let it record for 30 days, retrieve it, hope it catches the issue. Repeat the process to validate any corrective actions. That’s four or more truck rolls per issue—and even then, there’s no guarantee the distortion was corrected since harmonics can be seasonal.

As DER adoption accelerates and asset pressure increases, this reactive model is unsustainable.

Grid-Edge Visibility Is Now Essential

The growing complexity of the distribution grid necessitates a smarter, faster approach; one that begins with continuous network-level sensing at the grid edge.

Rather than relying solely on centralized monitoring or customer-side metering, utilities need real-time intelligence at the transformer level, where harmonic distortion strikes.

Modern edge analytics solutions now make this possible. These compact, cost-effective sensing devices can be mounted on pole-top or pad-mounted transformers and deliver:

• Real-time iTHD and vTHD readings by phase
• Harmonic alerts triggered instantly when thresholds are exceeded
• Historical distortion trends for planning, compliance and forecasting
• Event validation to confirm if corrective actions worked without a second truck roll

Just as importantly, these edge sensors help distinguish whether an issue is utility- or customer-originated, reducing finger-pointing and investigation delays.

Edge analytics not only simplify harmonic detection but also enhance how utilities prioritize asset replacement, manage DER hosting capacity and meet power quality standards, such as IEEE 519.

Harmonics Are the Canary in the DER Coal Mine

As electrification continues, harmonics may be one of the earliest and most telling indicators of grid strain. Unlike load data or outages, harmonic distortion doesn’t wait for a failure to signal a problem. It accumulates. It degrades. And without visibility, it wins.

Utilities that incorporate harmonic awareness into their asset management and DER integration strategies will be far better positioned to avoid unexpected failures, reduce operating expenses (OpEx) and lead confidently into the future.

The shift from reactive to proactive power quality monitoring is already happening. The question is whether you’ll be behind the curve or ahead of it.

Edge Zero provides real-time harmonic monitoring at the transformer level, helping utilities detect distortion, protect assets and reduce operational costs. Contact us to learn more.