Solis Inverter Harmonic Distortion/Harmonic Spectrum Data

This is a comprehensive guide to harmonic data for commercial and utility-scale inverters (25kW – 255kW).

As solar photovoltaic (PV) systems scale to meet the demands of the North American energy market, maintaining power quality and grid stability is paramount. A critical metric in assessing this stability is the harmonic distortion introduced by grid-tied inverters. To support our EPC partners, developers, and interconnection engineers, Solis provides transparent, highly detailed harmonic distortion test reports across our entire high-power portfolio. Below is a breakdown of what this data entails, how it is derived, and why it is a crucial component of your project documentation.

Which Solis inverter series does this document apply to?

• S6-GC(25-60)K-US
  
• S5-GC(75-100)K-US
• Solis-(125-255)K-EHV-5H-US-PLUS
• S6-GU(250-350)K-US

What is the Harmonic Distortion data?

The attached documents contain comprehensive harmonic current injection data for our C&I and utility-scale inverter models, spanning from the S6-GC(25-60)K-US series up to the SOLIS-255K- EHV-5G-US-PLUS. Rather than supplying a single, generalized Total Harmonic Distortion (THD) percentage, these reports deliver highly granular tabular data.

Specifically, the data details the individual current harmonics (both even and odd orders) generated by

the inverter across all three phases, extending up to the 40th, 50th, or even 100th harmonic depending

on the testing protocol for the model. This includes an analysis of Total Harmonic Distortion of Current

(THDi) and inter-harmonics, demonstrating that the inverters reliably maintain THDi well below the

strict thresholds (typically <3% or <5%) required at rated output power.

How did Solis derive this data?

This data is the result of rigorous laboratory testing conducted under highly controlled conditions by

our engineering teams. The testing framework subjects the inverters to various operational states to

capture a complete picture of their power quality performance.

Testing Conditions

We evaluate harmonic output under stringent parameters, including: Full Load Operations: Nominal rated DC voltage at 100% of rated active power. Varying Power Factors: Testing at maximum injection/absorption power factors, as well as unity power factor.

Frequency & Voltage Ranges: Ensuring compliance across the full operational MPPT voltage windows and standard grid frequencies (e.g., 59.5Hz to 60.5Hz).

These reports reflect verified engineering data logged by specialized power analyzers. They serve as the foundational evidence that the hardware complies with strict North American grid interconnection standards, including IEEE 1547 and UL 1741 grid support regulations.

Why is Solis providing this data?

Connecting large-scale commercial or utility solar assets to the grid requires extensive coordination

with utility companies and Authorities Having Jurisdiction (AHJs). We provide these detailed reports

proactively for three main reasons:

1. Accelerating Interconnection Approvals: Utilities frequently mandate comprehensive grid impact studies before granting Permission to Operate (PTO). By having the exact harmonic current spectrum available, interconnection engineers can seamlessly integrate this data into power system modeling software (like ETAP or PSCAD) to perform load flow and power quality analyses.
2. Proving Code Compliance: While a standard datasheet may simply state "THDi < 3%", many utility engineers require the raw testing data to verify compliance with local power quality limits and overarching standards like IEEE 519. These reports eliminate ambiguity.
3. System Design Assurance: For complex microgrids, sites integrating energy storage, or facilities with sensitive electrical equipment, knowing the precise harmonic signature of the inverters ensures that developers can properly design site-level filtering or mitigation, preventing unforeseen operational alarms or hardware degradation down the line.

We understand that robust hardware is only one piece of the puzzle. Providing the engineering data necessary to  deploy that hardware quickly and compliantly is just as important. Please refer to the attached documents for the specific harmonic profiles of your selected inverter models.