Everyone is selling something, whether it’s a physical product or an intangible, such as professional qualifications. As electrical contractors (ECs), it is your job to deliver solutions for electrical needs. However, on projects where efficiency and performance are directly tied to value and quality, shouldn’t you ensure the integrity of the work you stand behind?
Commissioning is the systematic process by which the EC verifies and documents that the installed system is safe, functional and meets the customer’s operational requirements. Specifically, in regard to photovoltaic (PV) systems, commissioning is very important because most PV systems installed on buildings are products of design/build projects where the electrical contractor is not only responsible for the PV system installation but also its performance.
By virtue of the design/build process, the contractor has already bought into the product’s performance, so it is prudent that the contractor ensure the quality of what it delivers.
Commissioning should be an integral part of the EC’s quality assurance program. It should include developing a written commissioning plan that includes measurable performance criteria and procedures for verifying the installed system meets those project requirements through ongoing inspection, testing and measurement.
Why commission PV systems?
PV system commissioning offers advantages to both the EC and the customer. From the EC’s perspective, the biggest advantage is that the process will demonstrate and document that the equipment and materials that make up the system were installed properly and that the overall system operates as intended. PV commissioning minimizes or even eliminates punch list items during project closeout, which in turn, results in an expedited project closeout and final payment as well as enhanced customer satisfaction.
For the customer, the benefits of PV system commissioning may even be greater; the process addresses risks associated with safety, operation and maintenance, and payback. First and foremost, the PV system must be safely integrated into both the building’s structure and power distribution system, and safety must be addressed in the commissioning process. An improperly installed PV system can present shock and fire hazards. The commissioning process needs to ensure that the PV system is installed in accordance with the National Electrical Code (NEC) as adopted and modified by the authority having jurisdiction (AHJ). In addition, all PV system equipment and materials must be tested and listed or labeled by an approved testing laboratory and installed according to the way they were tested in addition to manufacturer recommendations.
PV systems appear simple but are, in fact, complex, including a number of diverse components. The components’ individual performance characteristics must be matched to ensure the integrated system provides near optimal year-round conversion of sunlight into electric energy. The commissioning process should give the customer confidence that common design and installation pitfalls have been avoided.
For example, shading can significantly and detrimentally affect the energy output of a PV array. Shading can result from the physical environment surrounding the site or the installation itself. Other buildings, trees and the lay of the land can shade the panels as the sun changes positions in the sky daily and through the seasons. Similarly, the spacing between rows of PV modules and building appurtenances, such as parapets and other architectural features; building equipment, including roof-mounted heating, ventilating and air conditioning (HVAC) equipment; piping and vents; and similar objects; can shade modules and adversely affect PV system performance.
Installing a PV system is an investment, and most customers expect to see a return on their investment (ROI). A number of third-party high-performance and green building certification programs and energy codes require building commissioning, which specifically includes commissioning on-site energy production systems such as PV. Furthermore, payback on a PV system often hinges on the customer receiving government or utility incentives that offset the original cost of the system, such as grants or investment tax credits (ITC), along with possible ongoing buy-back provisions for excess energy delivered to the grid (such as net metering, feed-in tariffs or other incentives). The PV system commissioning process needs to address these requirements to ensure the customer qualifies for certifications and incentives, which will improve the customer’s ROI on the PV system. PV system commissioning should also establish a baseline for performance that can be used to compare against the original estimate and how it functions throughout its useful life.
What does PV system commissioning include?
The PV system commissioning process includes commissioning plan development, prefunctional inspection and testing, functional system testing, and system compliance and acceptance documentation.
Commissioning plan development
The first step in the PV commissioning process should be the development of a written plan that outlines the process, what activities are required in each step, the person by job title who is responsible for each activity, and how it will be documented. The EC should have a standard PV system commissioning plan available that project managers can modify and adapt to address specific project requirements and customer needs as required. The project-specific commissioning plan should be developed during design if the project is design/build or during the bidding or proposal process if the project is a traditional design/bid/build or “plan and spec” project.
If the EC has a field quality-assurance program, the PV system--commissioning plan should be part of it. The focus of the system-commissioning plan should be on demonstrating that the EC has met the customer’s expectations as expressed in the construction agreement. Demonstrating contract compliance can range from installation quality in a traditional design/bid/build plan and specification project to both installation quality and system performance in a design/build project.
Prefunctional inspection and testing
Prefunctional inspection and testing starts with PV system material and equipment delivery and ends when the system is fully installed and ready for the next step. This step in the commissioning process ensures all materials and equipment delivered to the project site are as specified and purchased, undamaged and in the right quantity, and properly stored until needed. Prefunctional inspection involves checking individual components as installation progresses to ensure they are undamaged and placed in accordance with the contract documents, applicable codes and standards, and manufacturer recommendations. For active PV system components, such as modules and inverters, prefunctional testing includes performing any tests required by the contract documents, manufacturer recommendations, or the EC to ensure the equipment is operating satisfactorily and is ready to be safely integrated into the system. Whenever possible or required by contract, the customer’s personnel should be involved in prefunctional system testing. The outcome of the prefunctional equipment inspection and testing should be documented through record installation drawings and photographs, completed EC and manufacturer installation checklists and measurements, and interim observation reports by the EC supervisory personnel, owner representatives and the AHJ.
Functional system testing
Functional system testing follows prefunctional inspection and testing and is focused on the operation of the PV system as a whole rather than just the quality of individual material and equipment installation. Beyond simply showing that the integrated PV system can convert available sunlight into electric energy, functional system testing will demonstrate that the system is safe and operating satisfactorily. Depending on the size and complexity of the PV system, the functional system testing of specific equipment may require a manufacturer’s representative to do the final checkout before system startup or just witness the startup to initiate the equipment’s warranty or guarantee.
Safety features, such as required ground-fault protection and inverter anti-islanding function, should also be tested to ensure proper operation. In addition, the AHJ will typically want to witness the testing of system safety features and should be included in appropriate functional system testing to avoid having to repeat the tests specifically for the AHJ.
On a design/build PV project where the EC is responsible for the system performance, functional system testing involves the EC demonstrating that the PV system meets the customer’s operational requirements, which will usually include system energy output and reliability. Often, initial energy production measurements will be sufficient to demonstrate contract compliance, but larger PV systems may require ongoing monitoring of system operation for a year or more to ensure contract compliance.
Documenting compliance and acceptance
The final step is assembling all of the commission documentation into a usable format and submitting the documentation to the customer for its use in operating and maintaining the PV system throughout its useful life. In addition to record drawings of the PV system installation, the documentation should include the electrical contractor’s commissioning plan, inspection and test records, photographs and any other compliance and acceptance documents provided by the AHJ, manufacturer representatives, a customer representative or others.
For design/build projects, design information may also be provided that would be helpful if the customer decides to modify or expand the PV system in the future. Equipment installation and operation manuals, quality assurance records, seismic certifications, manufacturer warranties and guarantees, testing and measurement records, shop drawings, and catalog cuts should also be provided to the owner along with any required spare parts, such as extra fuses or maintenance equipment. If the EC provides formalized training to the customer’s maintenance personnel, he or she should include a record of the training provided as well as roster of the customer’s personnel who attended. PV system compliance and acceptance documentation can be provided to the customer in hard copy paper-based format, electronic format or a combination of, depending on the needs of the customer.
PV system commissioning is good business
As discussed, PV system commissioning has many advantages for both the EC and the customer. The keystone of a PV marketing program is having a PV system commissioning plan as part of the electrical contractor’s field quality assurance program that focuses on the customer’s PV system performance requirements and operational concerns. Including a written PV commissioning plan with a proposal demonstrates that the EC is not just interested in doing the PV project but ensuring that the customer’s needs and expectations associated with the project are met. Furthermore, a PV commissioning plan shows that the electrical contractor is willing to demonstrate that customer requirements are met through ongoing documented inspection and testing activities throughout the project.
This article is the result of a research project, “The Emerging PV Market,” sponsored by ELECTRI International Inc. (EI). The author thanks EI for its support.
GLAVINICH is director of Architectural Engineering & Construction Programs and an associate professor in the Department of Civil, Environmental and Architectural Engineering at the University of Kansas. He can be reached at 785.864.3435 and firstname.lastname@example.org.