Consideration of soil parameters in sizing of a solar power plant

When it comes to sizing a solar power plant, one crucial factor that is often overlooked is the soil conditions. It is essential to consider the soil type and its properties, as it directly impacts the stability and longevity of the solar PV system. The type of soil can affect the foundation design, piling method, and overall cost of the project. In this article, we will explore the importance of soil conditions in sizing a solar power plant and the considerations that need to be made.

Soil conditions can vary greatly from site to site, and it is important to understand the properties of the soil before beginning construction. In the case of the solar power plant, the assumed soil type is “Normal Dry Type,” which is fairly flat, reasonably rectangular with clear boundaries, and undulations within +/- 100 mm. The N value, a measure of soil density and strength, is assumed to be between 10 to 50. The method of piling is auger, and the safe bearing capacity (SBC) of soil is 25 t/m2.

The soil type and its properties have a direct impact on the foundation design of the solar PV system. The foundation of the system should be designed to provide stability and support to the structure while ensuring that the system can withstand the weight of the solar panels and any external forces such as wind and snow loads. In the case of a solar power plant, the foundation can be designed using different methods such as driven piles, auger piles, or concrete spread footings.

The choice of piling method also depends on the soil type and its properties. In the case of the assumed soil type, the auger method is selected. The auger method involves drilling a hole into the soil and filling it with concrete, creating a solid foundation. This method is effective in soils with low N values, which are relatively weak and unable to support heavy loads.

In addition to the foundation design and piling method, the soil conditions also impact the overall cost of the project. Any changes in the soil conditions from the assumed values can lead to variations in the BOQ (bill of quantities) and contract price. It is, therefore, essential to conduct a thorough site analysis to understand the soil conditions accurately.

Soil resistivity is another important factor to consider when designing a solar power plant. The assumed soil resistivity is ≤ 50 Ωm. If the actual resistivity is found to be higher than 50 Ωm, which may necessitate a change in the earthing design, the contract price shall be adjusted accordingly. Soil resistivity affects the grounding system of the solar power plant, which is important for safety and effective operation.

Land cutting and filling are also important factors to consider when designing a solar power plant. In the assumed design, the land contours will be followed, and undulations within +/- 100 mm will be managed. Any cutting or filling that is required in spite of following the natural contours shall be charged extra on a unit rate basis. Land cutting and filling can affect the overall cost of the project, and so it’s important to consider this factor when planning the solar power plant.

The properties of the soil impact the foundation design, piling method, and overall cost of the project. It is crucial to consider the soil type and its properties before beginning construction and conduct a thorough site analysis to accurately assess the soil conditions. By doing so, solar PV systems can be designed and built with stability and longevity in mind, ensuring optimal performance and maximum ROI.