2026-04-28
1. Why Conduct a Site Assessment
Before installing a solar mounting system, it is essential to thoroughly understand the site conditions. Many people overlook this step, resulting in the system tilting, sinking, or even collapsing shortly after installation. The purpose of a site assessment is simple: to determine whether the location is suitable for installation and what type of foundation is required. You need to assess the site’s slope, drainage conditions, and any history of landslides or subsidence. You should also check for nearby trees or buildings that might block sunlight. If the site has obvious defects—such as low-lying areas prone to water accumulation or unstable slopes—these issues must be addressed first; otherwise, installing the mounting system will create safety hazards.
2. What You Need to Know About Geotechnical Surveys
A geotechnical survey involves excavating the ground to examine the soil composition beneath. Different soil types have vastly different load-bearing capacities. Hard clay or gravelly soil has high load-bearing capacity and can support shallow foundations. Conversely, loose fine sand, silt, or fill soil has very low load-bearing capacity, requiring either deeper foundations or replacement and reinforcement. During the investigation, at least one or two test pits must be dug, each with a depth of no less than 1.5 meters. The type, color, density, and moisture content of each soil layer must be recorded. If the site is large—for example, exceeding 1,000 square meters—a survey point must be established every 30 to 50 meters; a single point cannot be relied upon to represent the entire site.
3. How to Use Key Data
The investigation report will provide a set of key figures. The most important is the bearing capacity of the foundation, typically expressed in kilopascals (kPa). For example, the bearing capacity of compacted gravelly soil can exceed 300 kPa, while that of loose silt may be as low as 50 kPa. When designing a support foundation, you must ensure the base area is sufficiently large to distribute the pressure, keeping the actual pressure below the bearing capacity. Another important figure is the frost line. If your region experiences freezing temperatures in winter, the foundation must be buried below the frost line. Otherwise, soil heaving during winter will lift the foundation, and thawing in spring will cause it to sink. After several cycles of this, the support structure will become crooked. You can inquire with local engineering departments for the specific depth of the frost line.
5. Common Issues and Solutions
Several types of issues are commonly encountered during site evaluation. First, topsoil or humus may be present on the surface. This soil is loose and prone to settlement, so it must be excavated and replaced with crushed stone or gravel. Second, the water table may be too high—water may appear after digging just half a meter. Drainage is difficult on such sites, so it is recommended to use screw piles or cast-in-place concrete piles to place the foundation below the water table. Third, slopes or filled areas. Such sites are prone to slow slippage and require professional stability calculations. In summary, spending a few days on thorough site evaluation and geotechnical investigation can prevent the need to spend several times that amount later on repairing a tilted support system. Do not choose a location based on intuition; relying on data is the most reliable approach.
