Location: McLean, Illinois
Client: Special K Hog Farm (Commercial site)
System Size: 246.4 kW DC / 165 kW AC
Design Turnaround: Under 48 hours
Result: AHJ-approved on first submission
The Challenge
Every solar project comes with its own set of unique challenges, but this one demanded more than just technical skills. The client, a large-scale hog farm located in Funks Grove Township near McLean, Illinois, needed a complete permit-ready solar design in a very tight timeframe. The system required full compliance with 2020 NEC standards, 2021 IBC/IFC codes, and local AHJ ordinances. Ground-mounted systems already pose increased scrutiny from permitting authorities, and the rural jurisdiction meant we had to be exceptionally thorough in our approach to ensure a seamless first-time approval.
While most teams would need several days to compile the full design, calculate voltage drops, complete grounding requirements, and prepare PE-stamped drawings, our client needed everything finalized and submitted within 48 hours.
That’s where One Place Solar stepped in.
System Overview
The solar energy system we designed consisted of 448 VSUN550-144BMH solar modules, each capable of producing 550 watts of power. These were strategically arranged across 14 ground-mounted arrays, utilizing UNIRAC’s GFT racking system for enhanced structural reliability. We integrated 11 Fronius Primo 15.0-1 inverters, each rated for 15 kW of continuous output.
This configuration resulted in a robust 246.4 kW DC capacity and a 165 kW AC output, perfectly aligned with the energy needs of the commercial operation. The system included 28 strings, each with 16 modules, optimized for efficiency and minimal losses.
The design also incorporated a line-side tap interconnection method via an Automatic Transfer Switch (ATS), offering a reliable and scalable connection to the existing utility infrastructure and backup generator.
Our Detailed Design Approach
We approached the McLean project with a commitment to detail and speed. Our design was not just about connecting panels and inverters but creating a comprehensive electrical and structural package that would be easily approved by the AHJ without back-and-forth communication.
Structural Engineering
We began with a structural layout that considered wind speed (115 mph) and ground snow load (20 psf), using ASCE 7-10 standards. Each array was supported using UNIRAC’s C-Pile foundation with cast-in-hole concrete footings. Our structural drawings included diagonal bracing, E-W beams, and top chord channels to ensure long-term durability and compliance with the IBC.
These plans were professionally engineered and stamped by our licensed PE, making them ready for immediate permit submission.
Electrical Design
From a compliance and performance perspective, the electrical system was meticulously mapped. We conducted voltage drop calculations to ensure that losses remained below 3% across conductor runs, even in longer trenches measuring up to 342 feet. All conductors were sized and derated according to NEC guidelines, including temperature correction factors based on ambient conditions and roof temperatures.
Conduit fill calculations, ampacity derating, and OCPD sizing were completed per NEC 2020 standards. We used UV-resistant, wet-rated EMT conduit for all exterior wiring and included full grounding/bonding specs per NEC 690.47.
Every component—disconnects, inverters, RSD boxes—was selected for UL listing. We ensured the placement of AC/DC disconnects met accessibility requirements, including mounting heights under 6’7″, and implemented dual-power source labeling where needed.
Rapid Shutdown Implementation
A key safety feature in our design was the implementation of rapid shutdown capability across all 14 arrays. This was not just a code requirement; it was an essential fire safety component that protects first responders. We used UL-listed Rapid Shutdown Box-DUOs for each array, integrated at the string level.
Our labeling strategy aligned with NEC 690.56 and 705.12, and included clearly marked signage on all disconnects and junction boxes. The layout made it simple for inspectors and responders to identify all system elements.
What We Included That Others Often Miss
At One Place Solar, we go beyond the basics. Many design services deliver only the minimum—panel layout, single-line diagrams, and maybe structural drawings. Additional services like voltage drop calculations, conduit layout, trenching details, grounding plans, and rapid shutdown implementation often come at an extra cost—or worse, are left for the installer to figure out.
We delivered all of this by default:
- Complete Bill of Materials (BOM)
- Trenching and conduit routing plans
- Voltage drop and conduit fill calcs
- NEC/UL compliant labeling and placards
- PE-stamped structural and electrical drawings
- AHJ-specific notes and layout adjustments
And we did it in under 48 hours.
Final Outcome
The result of this effort was a complete, permit-ready design package that received AHJ approval without a single revision. Our client was able to proceed with installation immediately, saving days—if not weeks—of potential delays due to missing information or compliance issues.
The project demonstrated not just our speed, but our depth of expertise. It proved that a fast turnaround doesn’t require compromising on quality or compliance.
Why This Matters for You
If you’re a solar installer, EPC, or project developer who’s tired of permit rejections, constant redlines, and costly redesigns—know that there’s a better way.
At One Place Solar, we combine speed, accuracy, and compliance to help you get your solar projects permitted faster and built sooner. We don’t just design systems—we engineer success.
Let’s work together on your next project.
📧 info@oneplacesolar.com
📞 +1 209 682 5630 | AUS: +61489270294
🌐 www.oneplacesolar.com