How to Perform Power Quality Analysis in Large-Scale Solar PV Systems

By Jason Axelson, Fluke Subject Matter Expert, Power Quality

Large-scale solar PV systems are engineered for long-term output and stable operation. But issues like harmonic distortion, voltage unbalance, and inverter inefficiency can silently reduce energy yield and accelerate wear on critical assets.

For experienced technicians, power quality analysis offers a path to early detection and correction, preserving uptime, improving inverter performance, and avoiding unplanned maintenance or regulatory issues.

Key Power Quality Challenges in Utility-Scale PV

One of the primary challenges in solar PV systems is maintaining consistent power quality. Solar PV systems are inherently variable due to the intermittent nature of their energy source. Additionally, the process of converting direct current (DC) electricity into alternating current (AC) for grid distribution introduces potential issues such as:

• Fluctuating Voltage Levels: Variations in energy input can result in voltage imbalances that disrupt the stability of the power supply.
• Harmonic Distortion: The use of inverters for DC-to-AC conversion often generates harmonic currents, which can create waveform distortions in the electrical signal. High levels of harmonic distortion can lead to overheating, overloading of transformers and capacitors, and operational disruptions across the grid.
• Voltage Unbalance: Uneven voltage across phases can cause current unbalance, leading to wear and tear on equipment such as motors, which in turn increases maintenance costs and operational risks.

These challenges underscore the importance of conducting regular power quality analyses to identify and address potential issues early, ensuring that renewable energy systems operate efficiently and reliably.

Essential Tools for Power Quality Analysis in Solar PV

To conduct an effective power quality analysis, you’ll require specialized equipment, including:

• Power Quality Analyzers: These devices are designed to measure key parameters such as voltage, current, harmonics, and power factor. They allow you to pinpoint inefficiencies and irregularities in your energy system.
• Oscilloscopes: These are useful for visually inspecting voltage and current waveforms, which can help you quickly identify issues like transient events and waveform distortions.
• Data Logging Devices: These tools enable you to track energy consumption and power quality trends over time, providing valuable insights for long-term planning.

Selecting tools that are user-friendly, reliable, and compliant with industry standards can simplify the testing process and ensure accurate results.

Step-by-Step Guide on How to Conduct a Thorough Power Quality Analysis

Power quality analysis is a systematic approach to identifying and addressing inefficiencies and irregularities in electrical power systems.

Step 1: Verify Inverter Power Conversion Efficiency

What: Measure how effectively your inverter converts DC to AC power.

When: During installation and routine maintenance.

Why: Regularly monitoring helps identify trends that affect performance over time.

Tool(s):

• Fluke Norma 6000 Series Portable Power Analyzer

Actions: Connect to the DC input side and the AC output side of the inverter. Look for degradation trends over time. Regularly monitoring (monthly or quarterly) helps identify degradation in performance over time.

Step 2: Measure Voltage Unbalance Across Phases

What: Check for unequal voltage levels across the three phases of your system.

When: During commissioning, post-maintenance checks, and as part of quarterly preventive maintenance.

Why: Even minor unbalances can cause excessive current draw, heat buildup, and premature failure in motors and other three-phase equipment. Industry standards (e.g., NEMA MG-1) recommend keeping voltage unbalance below 1%.

Tool(s):

• Fluke 1738 Three-Phase Power Quality Logger
• Fluke 1760TR Three-Phase Power Quality Recorder

Actions: Connect the tool to all three phases. Record RMS voltages and calculate the unbalance percentage. Investigate persistent unbalances as they may indicate load distribution issues or wiring faults.

Step 3: Identify Harmonic Distortion

What: Detect and quantify harmonics generated by inverter switching and other non-linear loads.

When: During routine power quality audits or whenever equipment shows signs of overheating, malfunction, or intermittent faults.

Why: Excessive harmonics degrade power system efficiency, damage sensitive electronics, and shorten the life of transformers, capacitors, and motors. Regular tracking helps you prevent long-term degradation.

Tool(s):

• Fluke 1738 Three-Phase Power Quality Logger
• Fluke 1760TR Three-Phase Power Quality Recorder

Actions: Measure total harmonics distortion (THD) and compare it to equipment tolerances or IEEE 519 standards. Identify specific harmonic orders that may require filtering or inverter configuration.

Step 4: Capture Transient and Waveform Issues

What: Detect fast, high-frequency disturbances that disrupt equipment or indicate electrical faults.

When: After system faults, unexplained shutdowns, or inverter trips; also during performance commissioning.

Why: Transients can damage components or trigger protective shutdowns. These fast events often go undetected by loggers but are visible on an oscilloscope.

Tool(s):

• Fluke 190 Series III ScopeMeter™ Portable Oscilloscope

Actions: Connect to suspect circuits or inverter outputs. Use triggering features to capture irregularities in waveform shape, such as spikes, notches, or ringing. Document events for analysis and remediation.

Step 5: Log and Trend Power Consumption

What: Measure and trend energy usage across your system to detect inefficiencies and load anomalies.

When: Continuously for long-term trend analysis, or monthly during system health checks.

Why: Usage patterns reveal inverter cycling, unbalanced loading, and energy drift. This data better supports maintenance and expansion decisions.

Tool(s):

• Fluke 1738 Three-Phase Power Quality Logger

Actions: Set up long-term logging to track kWh consumption, power factor, and load variation. Analyze historical trends and correlate with environmental data or inverter logs to find efficiency opportunities.

Preventive Strategies to Maximize Solar PV Uptime

In addition to regular testing, consider implementing these strategies to enhance the power quality of renewable energy systems:

• Install Filtering Devices: Filters can mitigate harmonic distortion by removing unwanted frequencies from the power signal.
• Inverter Configuration: Use advanced inverter settings to minimize harmonic generation and improve power factor.
• Grid-Tied Management Systems: Implement systems that actively monitor and adjust power inputs to align with grid requirements, reducing fluctuations and imbalances.

Protecting ROI in Utility-Scale Solar Through Power Quality

In large-scale solar PV operations, every kilowatt-hour counts. Power quality monitoring isn’t optional, it’s a critical practice for minimizing downtime, extending equipment lifespan, and staying compliant with grid requirements.

With the right tools and regular analysis, field teams can ensure these systems deliver stable, high-quality power year after year.

About the Expert

Jason is a subject matter expert at Fluke specializing in power quality, electrical test equipment, and product applications. With deep experience supporting both customers and distribution partners, he helps professionals select, operate, and troubleshoot a wide range of diagnostic tools—including power quality analyzers, battery testers, acoustic imagers, and thermal imagers. Jason regularly leads application-based training sessions, drawing on his hands-on knowledge to bridge the gap between technical challenges and practical solutions across industries. Connect with Jason on LinkedIn.