How Strategic Planning and Precise Procurement Power Large-Scale Solar Installations

Commercial solar projects require more than just panels and permits—they demand precise engineering, logistics, and detailed material planning. When designing and delivering a system of this scale, having a well-prepared and accurate Bill of Materials (BOM) becomes just as important as the wiring diagrams or site plan.

At One Place Solar, every project we engineer is supported by a structured, permit-ready design package—and behind that package is a detailed breakdown of the materials that make installation smooth and scalable.

In this blog, we’ll walk you through the actual materials used in our 246.4 kW ground-mounted system for Special K Hog Farm in McLean, Illinois, and explain why every bolt, clamp, and rail plays a critical role in the success of the project.

Why the Bill of Materials Matters in Solar Projects

The Bill of Materials (BOM) is a foundational document that lists every component needed to complete a solar installation—electrical, structural, and mechanical. For large-scale systems, the BOM ensures:

• Accurate procurement and delivery of all required items
• On-time installation without field delays
• Cost control through precise quantity estimates
• Alignment with design specifications and product warranties
• Compliance with NEC, AHJ, and engineering standards

A properly developed BOM reduces uncertainty in the field and helps project managers coordinate with suppliers and installation teams more effectively.

McLean Project Overview: Building a 246.4 kW System

The Special K Hog Farm project is a grid-tied, ground-mounted system engineered by One Place Solar for agricultural operations in Illinois. It included:

• System size: 246.4 kW DC
• Modules: 448 x 550W VSUN550-144BMH
• Inverters: 11 x Fronius Primo 15.0-1
• Mounting system: Unirac GFT with pile foundations
• Arrays: 14 total, 32 modules per array
• Interconnection: Line-side tap into 400A load center with ATS

Structural BOM Highlights

1. Solar Modules

• Quantity: 448
• Type: VSUN550-144BMH
• These 550W bifacial panels were selected for high yield and efficiency. Modules were configured into 28 strings of 16 modules each.

2. Mounting Rails

• Quantity: 224
• These aluminum rails formed the backbone of the GFT structure. The total number reflects dual rail support for each row of modules.

3. Mid Clamps

• Quantity: 784
• Mid clamps secure panels between mounting rails and ensure alignment. Precision matters here to avoid over-compression or damage.

4. End Clamps

• Quantity: 224
• These anchor the outermost modules and contribute to the mechanical integrity of each row.

5. Grounding Clips and Bonding Jumpers

• Installed on each rail and between rows to maintain continuity per NEC 690.43.

6. Pile Foundations

• Steel piles were driven below frost depth to ensure structural integrity in Illinois’ cold weather and loamy soil conditions.

Electrical BOM Highlights

1. Inverters

• Quantity: 11
• Model: Fronius Primo 15.0-1
• These inverters were distributed across the system to maximize uptime and simplify wiring.

2. Rapid Shutdown Devices

• RS Box-Duo Units: One per string pair
• Ensured full compliance with NEC 690.12 for module-level rapid shutdown.

3. Combiners, Disconnects, and Breakers

• Included fused DC disconnects, AC disconnects, and combiner boxes rated for 600V DC.

4. AC and DC Conductors

• Conductor Type: Aluminum THWN-2 in EMT and PVC conduit
• Sized per NEC 310 and derated for temperature and conduit fill. Voltage drop kept below 2 percent.

5. Grounding Materials

• Ground Rods: 8 ft copper-clad steel rods
• Clamps and Lugs: Acorn clamps and lay-in lugs per NEC 250

Labeling and Signage – We included all required solar placards and safety labels in the BOM to meet:

• NEC 690.13–690.55
• Rapid shutdown markings
• Inverter labeling
• Interconnection and AC/DC disconnect identification

Each label placement is shown on the plan set and the BOM lists both quantity and type of signage required.

Logistics and Procurement Coordination

In commercial solar, one of the biggest causes of delays is incomplete or miscounted material orders. At One Place Solar, we take a design-led approach to procurement by:

• Matching every item in the BOM with exact design references
• Estimating extra quantities for site conditions (e.g., pile embedment tolerance, conduit routing variances)
• Coordinating with your procurement team to identify lead times and substitutions
• Supporting on-site field teams with documentation and layout maps to reduce install time

This level of preparation was key to the smooth installation of the McLean project, where precise trenching, pile spacing, and inverter grouping were pre-planned and documented before materials arrived.

Included in Every One Place Solar Permit Package

With every commercial solar project, we include a detailed bill of materials as part of our:

• Solar permit design
• Preliminary design package
• PE-stamped electrical and structural plan sets

This ensures your procurement, field, and installation teams are fully aligned with the design—reducing waste, delays, and uncertainty.

Final Thoughts: Precision Builds Better Projects

A well-prepared Bill of Materials doesn’t just list parts—it enables performance. It reduces field errors, improves installer productivity, and ensures the system is built exactly as designed.

At One Place Solar, we treat the BOM as an engineering deliverable, not just a supply list. It reflects our commitment to detail, reliability, and project readiness.

If you’re working on a commercial solar project and want to see how our documentation makes your build easier, faster, and more compliant, we invite you to connect.

Contact us today to request a sample bill of materials or permit plan set from the McLean project.