Getting to Constructibility: Due Diligence, Designing and Permitting Your Solar System

Sussex Energy begins evaluating your site with rigorous due diligence and precise system modeling. The design must be sized and tailored, and importantly, the financial projections must also be realistic. For businesses considering solar, this stage is critical to aligning expectations with results and securing confidence from any stakeholders, including lenders or investors. 

Utility Bill Analysis

The first step in the due diligence involves analyzing the site’s energy consumption and utility data. We typically review 12 months of full copies of utility bills for all of the facility’s meters to determine the offsetable charges, the “avoidable cost of power”. Electricity charges that are calculated on a per-kilowatt-hour (kWh) basis are considered offsettable by solar power generation, while fixed service charges and demand charges are generally not. Although solar installations may reduce demand charges, this potential reduction is not typically factored into initial financial analyses.  However, for a retail business with a more standard load profile and normal retail operation hours, a 10% demand reduction can sometimes be safely built into the assumptions.  All of this can be drilled down on a bit further with the utility interval data, also called an 8760 report; that is, a report ordered from the utility company for your meter showing your hourly consumption for all 8,760 hours of the year.  Then to project future energy costs, an inflation rate of approximately 3% is often applied, reflecting historical energy price trends.

System Modeling

Once the utility data is understood, the technical evaluation of the site begins. This involves creating a detailed 3D model of the building or property where the solar system will be installed. Accurate measurements, including building height, roof dimensions, and any obstructions, are integrated into the model. For complex structures or properties requiring roof work, precise aerial measurements are used. Obstructions such as HVAC equipment, parapets, and other rooftop structures are modeled to account for shading, and comply with setback requirements and fire code regulations, which typically include clearance for median access lanes and perimeter pathways.

Both the direct current (DC) system, including the layout of solar panels and their dc wiring connections, and the alternating current (AC) components, such as inverters, combiners, disconnect switches, and ac wiring, are modeled. Multiple iterations are run to evaluate different panels, inverters, racking, panel tilt angles, and wiring designs to find the most optimal combination of components.  This step considers performance, cost, availability, and compatibility with the specific site conditions and overall system design. The goal being to maximize energy yield while minimizing costs.

Shading Analysis

A comprehensive shading analysis is performed next. Using tools like LIDAR and ray-tracing software, we simulate how shadows from nearby trees, buildings, or other structures will move across the solar array throughout the year. This analysis identifies areas of the roof that receive the most consistent sunlight, optimizing panel placement and ensuring maximum energy production. Panels that experience excessive shading are either excluded from the design or strategically placed to minimize losses.

Financial Modeling

Bankable designs are created by engaging with banks and investors to verify production and yield estimates. Transparent and data-driven energy assessments reports are generated for an understanding of the system’s expected performance. Proper financial modeling is essential as it sets expectations with the business owner and lending partners regarding the system performance, and associated revenues and return on investment, and minimizes the risk of post-agreement financial adjustments.

Throughout the due diligence and modeling process, attention to detail and adherence to industry best practices are paramount.  By investing the time and resources into thorough evaluation and modeling, Sussex Energy will make sure that your solar project is designed for success.  Contact us today to explore how we can help turn your energy goals into reality.