Harvard University
Commercial Solar Guy | UL 3741 Project
Racking System: ecofoot 5d – ul 3741
Structure Type: educational
Location: CAMBRIDGE, MASSACHUSETTS
Completed: January 2025
Challenge
Harvard University sought to maximize clean energy generation on a prominent campus roof while navigating stringent permitting requirements and implementing advanced safety standards. The project required a cutting-edge, code-compliant mounting solution to meet UL 3741 requirements while eliminating attachment points, reducing rooftop components, and streamlining installation. The team also faced obstacles related to load factors, wiring complexity, municipal permitting delays, and the need for a robust racking system that could adapt to a roof with numerous preexisting obstacles and irregularities.
Solution
Commercial Solar Guy partnered with Unirac and SMA to deliver a state-of-the-art solar array using the EcoFoot 5D system and SMA inverters. The UL 3741-certified solution was chosen to eliminate the need for additional rapid shutdown components, simplifying the design and reducing failure points. Unirac’s engineering and design team worked closely with the installers to ensure a seamless process from quoting to implementation, while SMA provided robust inverters that integrated with Unirac’s racking system to meet UL 3741 standards. The EcoFoot® 5D bay system offers superior design flexibility and pre-cut wire harnesses contributed to efficient installation despite the unique challenges of the site and the complexity of the wire management trays.
Implementation
The Harvard project marked a significant milestone as a large-scale commercial installation leveraging UL 3741 safety standards. Upon joining the team, Construction Project Manager Sena Oran facilitated vendor communication and on-site logistics, ensuring the timeline stayed on track despite stated challenges. The racking system was adapted on-site to accommodate unforeseen issues with wiring paths and preexisting roof obstacles, including vents, and to avoid needing to customize ballast trays.
Ted Bleecker, Senior Director of Commercial Business Development at Unirac, highlighted the collaborative efforts that ensured success: “With our regional sales team and dedicated Commercial Services specialists like Robby Ryan, we provided unmatched support. From navigating a change in engineering and UL 3741 adoption challenges to tailoring the layout design of the EcoFoot 5D system for the project, our goal was to deliver a solution that exceeded expectations.”
Robby Ryan, Commercial Services Specialist for the Northeast, underscored the technical back-and-forth that led to the optimal design: “We worked closely with the design and installation team, iterating between RM5 and EcoFoot® 5D to meet the project’s specific needs, particularly achieving an attachment-free system while staying under the psf limit. The communication loop was pivotal to this project’s success.”
John Weaver, founder of Commercial Solar Guy, emphasized the value of UL 3741 in minimizing rooftop components and connections, reducing the risk of arc faults, and increasing system reliability. SMA’s inverter technology was key in achieving compliance, providing reliable rapid shutdown functionality without additional rooftop components. While initial site preparation required careful adjustments, the Unirac EcoFoot® 5D system enabled installers to maintain a high-quality build with fewer roof penetrations. Additionally, Unirac and SMA provided engineering support to address complex wiring layouts, ensuring compliance with municipal safety standards.
Patrick Edwards, the project’s master electrician, had some reservations about using UL 3741 and was concerned that it may cause delays with the AHJ. However, his doubts were about the ease of installation and AHJ approvals, and the fact that the local authority approved the project design without issue satisfied his concerns.
“UL 3741 ALLOWS US TO SIMPLIFY ROOFTOP INSTALLATIONS, REDUCING COMPLEXITY AND INCREASING SAFETY. UNIRAC’S SUPPORT AND SMA’S INNOVATIVE INVERTER SOLUTIONS MADE MEETING THESE HIGH STANDARDS ON A CHALLENGING SITE POSSIBLE.”
John Weaver | Founder, Commercial Solar Guy
Benefit
The Harvard UL 3741 project set a precedent for clean energy initiatives in Cambridge, Massachusetts. Key benefits included:
- Simplified System Design: Fewer components reduced installation complexity and failure points, aligning with the UL 3741 standard.
- Efficient Installation: Prefabricated wire harnesses and a modular racking design streamlined the build despite the site’s irregular layout and preexisting obstacles.
- Permitting and Compliance: Unirac’s extensive UL 3741 documentation and engineering expertise facilitated smooth interactions with local authorities and code compliance, while SMA’s advanced inverter solutions ensured seamless integration
with UL 3741 standards. - Safety and Durability: UL 3741 certification ensured robust safety measures without compromising performance.
List of additional faSYSTEM: EcoFoot® 5D with UL 3741 Compliant SMA Sunny Tripower CORE1 (x4) and a Sunny Tripower X
CAPACITY: 290.8 kWdc
PARTNERS: SMA America, Unirac, Inc.
DEVELOPER/EPC: Commercial Solar Guy & Patrick Edwards Electrical
