A utility-scale solar project is only as strong as the groundwork that supports it. Long before panels are installed and electricity begins flowing, the solar site work timeline begins with preparation, grading, and logistics that pave the way for efficient construction. For developers and contractors alike, understanding each phase in the timeline is critical for staying on budget, minimizing delays, and meeting production goals.
At Ansgar Solar, we specialize in large-scale solar construction and labor services across the Southeastern United States. Our teams support projects from day one, handling early-stage site work through to mechanical installation. In this article, we outline a typical solar site work timeline from clearing to commissioning, providing insight into the phases, the coordination involved, and what project owners can expect along the way.
Solar Sites Work Timeline
1. Site Assessment and Planning
Before physical construction begins, solar developers conduct extensive feasibility studies to validate a site’s suitability for solar power. This includes analyzing:
- Sunlight exposure
- Topography
- Soil conditions
- Drainage and flood risk
- Access to transmission infrastructure
Environmental impact assessments may also be required, especially for large sites. In the U.S., these assessments often follow the guidelines set by the National Environmental Policy Act (NEPA), managed by the U.S. Environmental Protection Agency (EPA).
During this stage, civil engineers and planners develop a layout optimized for solar panel placement, access roads, drainage solutions, and electrical infrastructure. Land surveys and geotechnical reports help determine where pile foundations or ballasted systems can be installed securely.
2. Clearing and Grubbing
Once a project is approved and permitted, site preparation begins. Clearing and grubbing involves removing trees, brush, rocks, and any surface obstacles from the project area. Depending on the site’s prior use (e.g., farmland, forest, brownfield), this step can take anywhere from a few days to several weeks.
Heavy equipment such as excavators, mulchers, and dozers are brought in to clear vegetation and level the land. Erosion control measures, like silt fences or sediment basins, are also installed to protect nearby water sources during construction.
3. Rough Grading and Access Roads
After clearing, the next step in the solar site work timeline is grading the land to match the design plans. This involves leveling the ground to provide a flat and stable foundation for solar panel rows and service equipment.
In some cases, minor cuts and fills are needed to create a uniform grade. At this point, construction crews also build gravel access roads throughout the site. These roads are vital for transporting materials and supporting ongoing operations and maintenance after the project is complete.
Rough grading also includes drainage swales and retention areas to prevent pooling water, which could impact racking stability or lead to soil erosion over time.
4. Pile Driving and Foundations
Once the site is cleared, graded, and accessible, the next phase is installing foundations. Most utility-scale solar projects use pile-driven steel posts to support racking systems. Specialized pile-driving machines are brought in to drive hundreds or even thousands of posts into the ground.
Pile locations must be precisely mapped using GPS or laser-guided systems, and spacing must align with the racking and module layout. Soil reports conducted earlier help determine the correct depth and type of pile foundation required to meet loading conditions, particularly in high-wind zones or areas prone to frost.
5. Trenching and Underground Work
While pile driving occurs above ground, trenching for underground electrical work happens concurrently. This includes:
- DC cable routing from modules to combiner boxes
- AC conduit runs to inverters and transformers
- Grounding and bonding connections
- Communication lines for monitoring systems
Trenching is usually completed with excavators and skid steers, with crews working in coordination to minimize conflicts between mechanical and electrical phases. Once cables are laid and connections are made, trenches are backfilled and compacted to meet electrical safety standards set by the National Electrical Code (NEC), managed by the National Fire Protection Association.
6. Racking and Module Installation
After foundations are set and wiring is in place, crews begin assembling racking systems. These aluminum or galvanized steel frames are attached to the piles and support the solar modules. Trackers may be installed during this step if the project includes single-axis tracking technology to increase energy yield.
Once racking is complete, solar modules are mounted row by row. Technicians fasten panels to the frame using torque-controlled tools, checking alignment and tilt angles to match the design. Electrical teams follow behind, wiring strings of modules and connecting them to combiner boxes.
7. Inverters, Transformers, and Commissioning Equipment
As the array takes shape, electricians install key pieces of infrastructure that convert DC electricity from the modules into usable AC power. These include:
- Central or string inverters
- Step-up transformers
- Switchgear and relays
- Metering equipment
This equipment is mounted on concrete pads or skids and must meet utility and interconnection requirements. Cabling is terminated, tested, and insulated according to design specs.
Once physical installation is complete, the commissioning process begins. This includes:
- System performance testing
- Ground fault and insulation resistance testing
- Inverter startup and tuning
- Grid synchronization checks
- Verification of monitoring systems
8. Final Inspections and PTO
Before a solar project can begin producing revenue, it must pass final inspections and receive Permission to Operate (PTO) from the local utility or grid operator. Inspectors review the installation for code compliance, safety, and alignment with approved plans.
Documentation for permits, interconnection, and test results is submitted. Once approved, the project transitions into the operational phase and begins generating electricity for the grid.
Typical Timeline by Phase
While each project is unique, a general solar site work timeline might look like this for a 50 MW project:
| Phase | Estimated Duration |
| Site Assessment & Permitting | 3–6 months (concurrent) |
| Clearing and Grubbing | 1–2 weeks |
| Rough Grading & Roads | 2–3 weeks |
| Pile Driving | 4–6 weeks |
| Trenching & Underground Work | 2–4 weeks |
| Racking & Module Installation | 4–6 weeks |
| Electrical Infrastructure | 3–5 weeks |
| Commissioning & PTO | 2–4 weeks |
Conclusion
Understanding the solar site work timeline gives project owners a realistic view of how long construction will take and what steps are involved. At Ansgar Solar, our crews support every phase of this process with the tools, experience, and manpower needed to move quickly and correctly.
By focusing on each detail, from clearing land to energizing panels, solar developers can meet production milestones and contribute to a more resilient, renewable energy grid.