From customer demand to the investment tax credit (ITC), many factors are fueling an increase in utility-scale solar photovoltaic (PV) projects across the U.S. These trends are also bringing new solar construction firms into the market. As the benefits of solar come to light, utilities should carefully consider siting options, equipment selection and installation requirements for success.
Dig Deep Into Site Characteristics
Thorough geotechnical engineering analysis is essential to determine suitable foundation design, soil mechanics and site characterization. Assessment must consider and evaluate soil composition, groundwater level, bearing capacity, and bedrock options and obstacles. Complete geotechnical data are critical to design and construct a robust and cost-effective solar PV foundation.
Driven pile installations are commonly recommended for utility-scale solar, but the geotechnical report will discuss whether other foundations are recommended, such as predrilled pile, and other specified civil recommendations across the site.
Project analysis will include cost, site output, interconnection requirements and solar performance modeling to determine the appropriate solar PV system. While a fixed-rack PV system is suitable for some smaller-scale projects, many utility-scale PV projects will benefit from a solar axis tracker system, depending on whether the site can meet the required grade variations necessary.
Evaluate Equipment Selection
Once site selection, foundation suitability and system design are selected, careful consideration should be given to the components and equipment required for high-quality solar construction.
- Solar Modules: With increased solar demand and a resulting shortage of solar modules, utilities must evaluate manufacturers and procurement options, in addition to comparing costs between PV power classes and assessing module quality. Utilities should gain an understanding of the vendor PV design approach, field performance and product reliability data. Some older solar technologies are more readily available during supply shortages, and these can be evaluated to determine if, although not the latest technology, they will meet project cost, schedule and performance requirements.
- Inverters: PV inverter evaluation typically centers on reliability to avoid component failure, issues or ongoing maintenance. Manufacturers that embrace a continuous improvement approach to design and production can provide field data to inform reliability expectations for specific project requirements. The selection must consider site characteristics, environmental conditions including thermal stress, internal heat generation and component efficiency.
- Wiring Management and Enclosures: Wiring options vary across the industry from wire ties to cable string systems to cable trays. The key is to understand, up front, what system is being proposed and its associated cost. Utilities should request to see a mockup row based on the proposed design, followed by agreement and approval among all parties before further installation.
The selection of enclosures and cabinet types for inverters, transformers and components are dependent on site characteristics, cost and available options from device manufacturers. Regardless, installation must follow manufacturer requirements to make sure enclosures are correctly sealed to keep moisture and pests out.
Insist on Experienced Installation
Solar PV system installation for quality and long-term operational performance requires experienced construction and commissioning. PV systems, especially on a large scale, present electrical, mechanical and structural construction complexity. In every instance, utilities should evaluate the reputation and industry experience of engineer-procure-construct (EPC) contractors.
Utilities should be aware that quality solar project construction includes close adherence to selected equipment manufacturer installation recommendations. Vendor requirements can be demanding but aim to deliver quality control, maximize performance and achieve optimal solar productivity. Guidelines must be followed exactly, and it is advised that installation includes photos and videos of the process at every stage to document correct receiving, unloading, storage and installation of equipment.
No matter how small or large, the success of utility solar PV projects is dependent on upfront site evaluation, selection of reliable components and quality construction and installation.
Solar installations benefit from a single-source EPC approach that navigates the changing marketplace, streamlines schedules, delivers a high-quality project and gives the owner peace of mind.