Feb 16, 2023

Solar 101 Series - UL 3741 Certification: A Better Solution for Firefighter Safety & Code Compliance

What can Onyx do to better ensure firefighter safety and code compliance?


The solar industry, as with all relatively young industries, is ever-changing, expanding and growing each day to incorporate new technologies, standards and local authority / jurisdiction (AHJ) guidance. While inarguably a laborious task to track and implement new innovations, the efforts have led to advanced cost-effective solutions for solar project developers and operators in this competitive industry.

One particularly salient and noteworthy improvement process relates to UL Certification – a process by which products and equipment are evaluated by the Underwriters Laboratories (UL) to ensure certain safety standards are met prior to operation. This may include evaluating product design, construction and/or materials, as well as conducting various tests to assess safety and reliability.

Currently, Onyx has multiple projects in design across the country utilizing this solution, and we anticipate that we will roll out the first utilizations of this certification in Q2-Q3 2023.

More on UL Certification

Once a product has been UL certified, it has been tested and evaluated by a trusted third-party organization that has determined it to meet the required safety and performance standards. This provides consumers peace of mind when purchasing the product, knowing that it has undergone a thorough safety evaluation.

The level of certification of UL 3741 in particular is a simple yet effective certification that addresses the prevailing issue of adherence to NEC 690.12, which pertains to the Rapid Shutdown of PV Systems on Buildings. The basis of this code section was to address the safety of firefighters that may climb across live (electrified) solar arrays. Since the introduction of said section (NEC 690.12) in 2014, various solutions to this code have been introduced yet proven unsuccessful. With the implementation of UL 3741, which utilizes the basic concept of simplifying array layouts, developers and installers prioritize a reduction in electrical components which thereby increases firefighter safety and ease code compliance.

”NEC 690.12 - Rapid Shutdown of PV Systems on Buildings. PV system circuits installed on or in buildings shall include a rapid shutdown function to reduce shock hazard for emergency responders.”

One could argue that this solution is not viable for all roofs, as some more complex multi-level roofs (such as those founds in schools) may prove difficult, as a “one size fits all” solution may be too ideal for an industry such as solar. In the case of large, flat roofs that are common in the C&I solar sector, this might prove to be a more than viable solution.Module-level power electronics (MLPE), better known as rapid shutdown devices, have been the go-to solution for adherence to NEC 690.12.

However, this solution comes with some known problems such as extra electrical connections, communication signal interference and arc flash events. With many more racking manufacturers starting to achieve the UL 3741 certification for their products, developers and contractors can more easily implement these solutions as an effective alternative to MLPEs.


Here at Onyx, we strive to utilize the most up-to-date technology for our partners, and when it comes to UL 3741, we are actively working with racking vendors who have adopted (or are in the process of adopting) this certification to implement at applicable sites.

Currently, Onyx has multiple projects in design across the country utilizing this solution, and we anticipate that we will roll out the first utilizations of this certification in Q2-Q3 2023.

Get in touch with us to learn more about how we can ensure the highest level of product and equipment safety and certification for your organization today!