Commissioning Solar PV Systems

Here are six reasons why these renewable energy systems should undergo the commissioning process before startup.

By Svein Morner, P.E., Ph.D., CCP, LEED AP
From the October 2018 Issue

Whether a solar energy project is sized to produce kilowatts or megawatts, commissioning a photovoltaic (PV) system demonstrates that the system is designed, installed, and working as promised. Building owners and facility management may be hesitant to engage in the commissioning process, viewing it as an additional layer of work and financial investment to a system that may already require up to 10 years of payback. Commissioning, however, can save time and money; ensure system efficiency and safety; and increase end-user satisfaction, especially when introduced in the planning phases. It’s also an essential part of a well-installed system, as the moderate investment PV commissioning entails facilitates future operations and maintenance. In addition, PV commissioning prevents the waste of unnecessary silicon, aluminum, glass, steel, copper, dollars, and effort. Moreover, commissioning builds public confidence in PV and renewable energy technologies.

PV systems commissioningAccording to the Building Commissioning Association (BCA), commissioning is “a quality-oriented process for achieving, verifying, and documenting that the performance of facilities, systems, and assemblies meet defined objectives and criteria. The commissioning process begins at project inception (during the pre-design phase) and continues through the life of the facility. The process includes specific tasks to be conducted during each phase in order to verify that design, construction, and training meet the owner’s project requirements.”

The basic tasks of commissioning are to:

  • Verify that the design meets the owner’s project requirements
  • Verify that applicable equipment and systems are installed according to the contract documents, manufacturer’s recommendations, and industry accepted minimum standards
  • Verify installing contractors perform adequate operations checkout
  • Verify/document proper performance of equipment and systems
  • Verify that the operations and maintenance documentation left on-site is complete
  • Verify the owner’s operating personnel are adequately trained

Here, in greater detail, are six reasons why PV systems should incorporate commissioning.

To ensure the PV system meets client goals. It’s a simple reason, yes. But if a client’s goal is to construct and operate a net-zero facility, for example, architects, engineers, and contractors need to understand this in order to design to meet that goal. The commissioning process keeps them focused. Other client goals might include maximizing return on investment, maximizing power output from roof space, or optimizing the PV system size to the utility rate structure. Known as the owner’s project requirements (OPR), these goals are part of the PV system designers’ installation and maintenance strategy: documents that outline the system components and performance-output calculations, which guide the PV commissioning process.

To minimize surprises. Using a commissioning service to ask essential questions during pre-design and design processes will uncover items that could create big problems during installation or operation. These questions could relate to the energy output of the system to those more technical in nature, like the sizing of the electrical wires and components.

To realize the system’s full capacity. The more an owner aims to accomplish with a system, the more complicated it can become. If a battery (or other energy storage) is tied to the PV system, for example, the system may have more difficulty providing the owner with “full bang for their buck.” Commissioning can include regular monitoring of electrical output and capacity, and checks to make sure all arrays are generating electricity, the converters are working optimally, and electric wires were properly installed and remain connected.

To keep contractors accountable. While most contractors fulfill their orders, sometimes a worker may forget to “dot their i’s and cross their t’s”, or they may devise a time-saving alternative without considering the maintenance problems it might create. The commissioning process keeps contractors accountable and brings to light issues that don’t meet project requirements.

To ensure the system works from the get-go. Every owner wants the system work without errors—right from the start. But not every aspect of the system may come online perfectly at first. Components (inverters and panels) may fail, or wiring may be inadequate.

To deliver, over time. Changes to the area adjacent to the panels may reduce their efficacy—like trees or new buildings that shade the system. Or, the owner may decide to incorporate equipment upgrades. PV commissioning ensures the system enjoys optimal operation even as environmental conditions or technologies change. Also, without commissioning PV system failures can go unnoticed for months (or years) if the building has a solid back-up via grid electricity.

PV systems commissioningMorner is a founding principal of Sustainable Engineering Group, recently acquired by HGA , and he has more than 20 years of experience in commissioning, retro-commissioning, energy efficiency engineering, and research. He has served as a commissioning authority for commercial and institutional buildings. Morner has also conducted extensive thermal storage research and created guidelines for heating, ventilation, and air conditioning of chemical, nuclear, and biotechnical laboratories.

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