UL 1741 SB, UL 9540, & UL 3141 PCS - CEC, LUMA, & HECO Approved Lists

Note: This article is strictly for the S6-EH2P(9.6-16)K03-SV-YD-L-US residential low-voltage (split-phase) hybrid inverter series for the US and Canada. The “Test Report Clips” included for download in this article are NOT the full test reports but only the first several pages of each. This is because we are not permitted to share the full test report without a signed NDA. If for some reason you need the full report, please contact solisservice@solisinverters.com and request to sign an NDA and specify which report you would like sent.

UL 1741 SB: The "Three-in-One” Inverter Certification

UL 1741 SB (Supplement B) is the current benchmark for grid-interactive smart inverters. It ensures that the inverter complies with the latest IEEE 1547-2018 standards, equipping the hardware to actively support grid stability through advanced functions like voltage ride-through, frequency regulation, and reactive power support.

However, achieving UL 1741 SB for the S6 residential series is actually a massive three-in-one testing accomplishment. To meet the stringent requirements of the Supplement B standard, the inverter must also simultaneously pass two other critical safety evaluations:

• UL 1998 (Software in Programmable Components): Because modern smart inverters rely heavily on software to manage protective functions and grid interactions, the code itself must be bulletproof. UL 1998 evaluates the functional safety of the software, ensuring that microcontrollers and algorithms will fail safely and operate reliably under fault conditions.

• UL 1699B (Photovoltaic DC Arc-Fault Circuit Protection): Residential solar arrays carry significant DC voltages. UL 1699B tests the inverter’s integrated Arc-Fault Circuit Interrupter (AFCI) capabilities. This ensures the system can rapidly detect and mitigate DC arcing faults, drastically reducing fire risks on residential rooftops.

By rolling UL 1998 and UL 1699B into the overarching UL 1741 SB evaluation, the residential S6 series was proven to have ironclad software reliability, advanced fire safety, and modern grid-support capabilities all operating cohesively.

UL 9540 Edition 3 DC ESS

As energy storage technology advances, the safety standards governing it evolve as well. For builders, installers, and homeowners, navigating these changing requirements can sometimes cause confusion during the permitting process. The transition from UL 9540 Edition 2 to Edition 3—specifically the introduction of the DC ESS (Direct Current Energy Storage System) classification—marks a significant shift in how battery systems and inverters are certified.

Understanding this difference is crucial for streamlining your installation and passing inspections.

The Core Difference: Combined vs. Independent Certification

Historically, energy storage systems were evaluated as a single, paired unit. The updated standard separates the battery from the inverter, allowing for more modular and flexible system designs.

FeatureUL 9540 Edition 2UL 9540 Edition 3 (DC ESS)Certification ScopeCombined system (Battery + Inverter)Battery system onlyDocumentationSingle certificate listing both componentsSeparate certificates for each componentInverter StandardIncluded in the UL 9540 listingHandled independently via UL 1741 SB

Under the older Edition 2, the inverter and the battery had to be tested and listed together on the exact same UL 9540 certificate. If an inverter wasn't explicitly named on the battery's certificate, the pairing wasn't recognized.

Under Edition 3 DC ESS, the safety evaluation for the battery is decoupled from the inverter. The UL 9540 DC ESS certification applies only to the battery itself.

What This Means for the 16K Hybrid Inverter

Every compatible battery for the 16K currently features the updated UL 9540 Edition 3 DC ESS certification. Because this new standard isolates the battery's safety listing from the inverter, Solis inverter models will not appear on these UL 9540 certificates. This is not an omission; it is exactly how the Edition 3 DC ESS standard is designed to work. The battery partners hold the primary UL 9540 certification for their hardware, while the inverter is certified under its own rigorous safety standard.

UL 3141: Power Control Systems (PCS)

The UL 3141 standard rigorously evaluates how an inverter electronically manages power flow, ensuring it can safely limit current without solely relying on traditional hardware like circuit breakers. For the S6 residential hybrid inverter series, the PCS functionality is entirely integrated into the inverter itself, meaning no external, third-party PCS hardware controller is required to achieve these capabilities.The system is officially classified to manage and regulate power from multiple sources simultaneously (e.g., PV, Energy Storage, and the Grid). 

• Power Export Limiting (PEL) electronically caps the maximum amount of power sent back to the utility grid. Critical for strict interconnect agreements or zero-export requirements. 
• Power Import Limiting (PIL) restricts the maximum amount of power drawn from the grid, ensuring the home does not exceed its allowed electrical service capacity. 
• Busbar Overload Control (BBOC) dynamically monitors and controls power flows to ensure the physical busbar in the home's electrical panel is never overloaded. This often allows for larger solar and storage installations without triggering expensive Main Panel Upgrades (MPUs).

Comprehensive ESS Operating Modes

The inverter supports and is certified for all four Energy Storage System (ESS) operational modes, giving installers maximum flexibility to comply with various utility tariffs and programs. These modes are not selectable in the inverter settings. Each one is achieved through a combination of settings being configured properly. Please see this article for details on energy storage, battery, and export power management settings: 

• Unrestricted Mode: The battery can freely import from and export to the grid.
• Export Only Mode: The battery can discharge to the grid but will not draw grid power to charge.
• Import Only Mode: The battery can charge from the grid but will not discharge power back to the grid.
• No Exchange Mode: The battery operates entirely independently of the grid (no importing or exporting).

What is Not Included in this Specific Certification

To ensure precise system design and compliance, it is equally important to understand which PCS configurations were notpart of this specific testing scope:

• Feeder Conductor Overload Control (FCOC) & Branch Conductor Overload Control (BCOC): While the inverter is certified to protect the main panel busbar (BBOC) and manage overarching import/export limits, it is not specifically classified to provide isolated overload control for individual downstream branch circuits or specific feeder lines.
• Single Source PCS (SSOC): Because the residential S6 hybrid inverter inherently manages multiple energy sources (solar, battery, grid), it is classified strictly as a Multisource PCS, making the Single Source designation inapplicable.

Hardware Requirements for PCS Functionality

To fully activate and utilize the Power Control Systems (PCS) capabilities, the S6 residential hybrid inverter must be installed with precise metering and current-sensing hardware. Achieving PCS compliance requires the inverter to be paired with approved split-core Current Transformers (CTs) or compatible split-phase smart meters to accurately monitor and control site power flow.

To streamline the installation process and ensure out-of-the-box readiness for standard residential deployments, the required grid-monitoring CTs or associated metering hardware are conveniently included in the same box as the inverter.

Accessing the Full Test Reports

We are committed to transparency and are proud of the engineering that went into passing these rigorous standards. For partners, installers, and system designers requiring deeper technical insights, the full, detailed UL 1741 SB and UL 3141 test reports are available upon request. Attached here are: (1) UL 1741 SB certification, (2) UL 1741 SB Test Report Cover Page, and (3) UL 3141 PCS Test Report [first 7 pages only].

Please note: Due to the proprietary nature of the internal schematics and software architecture detailed within these documents, full test reports can only be shared after the execution of a standard Non-Disclosure Agreement (NDA).

How to Find Solis Hybrid Inverters on the CEC Approved Lists

When verifying grid compliance and power control capabilities for your residential installations in California, you will need to reference the California Energy Commission (CEC) approved equipment lists.

Because Solis is the global brand name, you will not find the inverters listed under "Solis." Instead, all Solis hybrid models, including the S6-EH2P(9.6-16)K03-SV-YD-L-US series, are officially registered under the parent company and legal manufacturer name: Ginlong Technologies Co., Ltd.

Here is exactly how to find the equipment on both required lists:

1. The CEC Solar/Battery Inverter List

This list verifies that the inverter meets California's grid-support and safety requirements (including UL 1741 SB).

1. Go to https://solarequipment.energy.ca.gov/Home/InvertersList
2. Download the Excel file by clicking “Download Excel file” on the right side of the page.
3. In the Manufacturer column, do not look for “Solis." Scroll down until you get to "Ginlong Technologies Co., Ltd.” 
4. All Solis models for the US and Canada can be found under the manufacturer name “Ginlong”.

2. The CEC Power Control Systems (PCS) List

This list verifies that the inverter has passed UL 3141 and is approved to electronically limit current and power without relying strictly on traditional hardware breakers.

1. Go to https://solarequipment.energy.ca.gov/Home/PowerControlSystem 
2. Download the Excel file by clicking “Download Excel file” on the right side of the page.
3. In the Manufacturer column, do not look for “Solis." Scroll down until you get to "Ginlong Technologies Co., Ltd.” 
4. All Solis models for the US and Canada can be found under the manufacturer name “Ginlong”.

Tip: If you are submitting interconnection applications or permits, always ensure you write "Ginlong Technologies Co., Ltd." as the manufacturer to avoid processing delays with local utilities or Authorities Having Jurisdiction (AHJs).

HECO and LUMA Approved Lists

Just like the CEC databases, remember to search for these approved models under the official manufacturer name, Ginlong Technologies Co., Ltd., rather than "Solis" when referencing the HECO and LUMA equipment lists.