Ground-mounted systems are probably the simplest way to install solar on a larger scale compared to other types of installations such as roofs or parking structures. These systems can be held down by a variety of foundations, including concrete footings, pile driven posts, piers, metal earth screws or with ballasted holding trays.
One size fits all?
Foundation systems need to correspond to the existing site considerations and soil static conditions according to engineering calculations and building codes. The one size fits all approach will not lead to the most cost and resource efficient results. Here are some key factors that will help to determine the foundation type:
- Tilt angle and tracking characteristics of the solar power system.
- Local design wind speeds and snow loads (If applicable) where the solar power system is to be installed.
- Support and racking configuration.
- Overall solar module system size and weight.
- Local design codes and project requirements.
- Soil characteristics relative to friction, sliding, consolidation, slope stability, salinity, etc.
- Brownfield or landfill
Foundation types 101
The following table provides an overview of aspects to consider when choosing the appropriate foundation for a ground mounted solar array.
Regardless of the type of installation method all solar installations need a stable and secure support system and foundation. The longevity of the investment is determined by the weakest part of the system. Therefore it is essential to provide a quality, engineered foundation which suits the needs of each individual project and application. Choosing the right solar module support system method involves understanding a variety of environmental and soil mechanical factors.
Helge Biernath is the President & CEO of Sunstall, an installation company in California with the main focus on large solar projects. His company consults clients to find optimized racking and foundation solutions.