What to Expect: The 5 Key Factors of a Commercial Solar Site Assessment

You’ve analyzed the potential ROI, you’re excited about the tax credits, and you’re ready to explore solar energy for your business. The very next step is a commercial solar site assessment.

This is a critical process where a solar professional visits your property to determine the feasibility, optimal design, and potential energy production of a solar panel system. It’s a data-gathering mission that moves your project from a rough estimate to a concrete, actionable proposal.

While it might seem like a simple matter of looking at your roof, a professional site assessment is a detailed technical evaluation. Here are the five key factors that an installer will analyze.

1. Roof Analysis: Condition, Size, and Type

The most common location for a commercial solar installation is the roof, so it’s the first and most important area of inspection.

• Structural Integrity: The first question is: can the roof support the weight of a solar array? The installer will assess the age and condition of the roof structure and membrane. If your roof is old or nearing the end of its warranty, it’s almost always more cost-effective to replace it before installing solar panels, which have a 25-30 year lifespan.
• Available Space: The installer will measure the total usable roof area, carefully noting the location of all obstructions. HVAC units, vents, skylights, and parapet walls all create shade or take up valuable space that can’t be used for panels.
• Roof Type and Pitch: Is your roof flat (most common for commercial buildings) or pitched? Is it a membrane, metal, or gravel roof? The type of roof determines the specific mounting and racking system that will be used to secure the panels, which impacts the cost and complexity of the installation.

2. Shading Analysis: The Energy Production Killer

A solar panel that is even partially shaded can see its energy output drop dramatically. A thorough shading analysis is crucial for an accurate production estimate.

• Identifying Obstructions: The installer will identify anything that could cast a shadow on the roof throughout the day and year. This includes nearby trees, adjacent buildings, and even the property’s own parapet walls and rooftop equipment.
• Using Specialized Tools: Professionals use tools like a Solar Pathfinder or specialized software with 3D modeling. They can simulate the sun’s path across the sky for every day of the year to create a “shade map” of the roof.
• Optimizing the Layout: The results of the shading analysis directly inform the final panel layout. The design will place panels in the areas of maximum, year-round sun exposure to ensure the highest possible energy production.

3. Electrical System Evaluation

A solar array is an electrical power plant. It must be safely and efficiently integrated into your building’s existing electrical system.

• Main Service Panel: The assessor will inspect your main electrical panel to determine its capacity. Is there enough room and available amperage to handle the new circuit from the solar array? In some cases, the main panel may need to be upgraded to accommodate the new power source.
• Interconnection Point: They will identify the most logical and cost-effective point to “interconnect” the solar system with your building’s electrical infrastructure.
• Conduit Paths: The installer will map out the path that the electrical conduit will take to get from the panels on the roof down to the inverters and the main electrical panel, ensuring a clean and safe installation.

4. Historical Energy Consumption Analysis

To design a system that meets your financial goals, the installer needs to know how much electricity you actually use.

• Reviewing Utility Bills: You will be asked to provide at least 12 months of your past electricity bills. This data is crucial.
• Understanding Your Load Profile: The bills reveal not just how much energy you use, but when you use it. Do you have huge energy spikes during the day when machinery is running? This “load profile” helps the designer size the system appropriately to offset the most expensive peak-time energy usage.
• Right-Sizing the System: The goal is not always to offset 100% of your usage. Based on utility net metering policies and your financial goals, it might be more cost-effective to design a system that offsets, for example, 80% of your consumption.

5. Site Access and Logistics

This is a practical assessment of the construction process itself.

• Access to the Roof: How will workers and materials get to the roof? Is there a secure internal access hatch, or will a crane or lift be required?
• Staging Area: Is there a secure area on the ground where materials like panels, racking, and inverters can be stored during the construction phase?
• Safety Considerations: The installer will note all safety requirements, such as the need for perimeter flagging or fall protection, to ensure the project is completed safely and in compliance with all regulations.

After evaluating these five key factors, the solar installer will have all the data needed to provide you with a detailed, accurate, and reliable proposal. This proposal will include the final system design, a firm price, a precise energy production estimate, and a confident financial analysis of your long-term ROI.