Cost-Effective O&M for Commercial Systems

As the commercial PV market becomes increasingly competitive, the industry is looking for ways to increase revenue while simultaneously decreasing costs. O&M is one area that presents some opportunities. Many of the O&M considerations that impact cost and revenue—such as performance optimization, system uptime and operational efficiency—relate directly to inverter and monitoring system selection.

Improving Performance Ratio

The performance ratio for a commercial PV system compares the actual energy production to its theoretical energy-generating potential. This ratio, typically expressed as a percentage, quantifies the conversion efficiency of a PV system, as calculated based on measurement of irradiance, temperature and ac output. A basic goal of O&M activities is to ensure that a PV system’s actual output is as close as possible to its theoretical potential.

Reduce mismatch. One of the ways that system integrators and O&M providers can improve the performance ratio in a commercial system is to eliminate power losses caused by module mismatch. Increasing MPPT granularity is an effective means of reducing and potentially eliminating mismatch losses. All else being equal, string-level MPPT incurs fewer mismatch losses than inverter-level MPPT, and module-level MPPT reduces mismatch losses even further. Module-level power electronics (MLPE) effectively mitigate mismatch risks associated with system shading, differential aging, new roof obstructions and soiling.

Reduce downtime. While system integrators can limit module mismatch within a PV system by design, they can never eliminate all module defects or failures. In the event of decreased system production or product failure, O&M providers need to be able to quickly identify and respond to the problem and minimize system downtime. In central- or string-inverter–based systems, O&M can be time consuming. Even if zone- or inverter-level monitoring indicates a failure, field technicians know that the labor required to locate the problem increases with array capacity. In contrast, module-level, cloud-based monitoring allows O&M staff to precisely and remotely pinpoint failures in fielded systems.

With MLPE installed, certain aspects of O&M just require a few clicks on a computer or taps on a tablet. Highly targeted activities in the field reduce system downtime even further. Compared to a standard 30 kW string inverter, for example, a commercial PV system deployed with 600 W–rated MLPE offers 50 times better monitoring resolution. MLPE also provide a degree of future proofing, as you do not need to stock identical replacement modules, but can substitute any available module.

Improving Operational Efficiency

The more insight O&M providers have into system performance, the more efficiently they can operate. There are two different types of O&M activities: preventative and corrective. Preventative maintenance aims to maintain the system at its peak condition and limit downtime; providers conduct corrective maintenance, including repair, after discovering an issue.

MLPE address both types of activities. Module-level monitoring automates preventative maintenance activities by eliminating the need for time-consuming electrical tests that potentially expose workers to electrical hazards. It also expedites corrective maintenance by pinpointing problems and allowing providers to make fewer trips and spend less time on-site. With MLPE in place, for example, a module with a failed diode automatically triggers an alert to notify the O&M provider. This alert not only identifies the physical location of the problem, but also provides a screenshot that the O&M provider can use to initiate a warranty claim. The next time the O&M provider visits the site, a service technician can replace the failed module.

In addition to reducing O&M costs and improving return on investment, module-level monitoring also allows O&M providers to develop new revenue streams by offering different levels of O&M services. “Any serious O&M solution starts with a good monitoring system,” notes Jonah Liebes, senior vice president of professional services at HelioPower, an integrated energy solutions company based in Southern California. “HelioPower offers a complete suite of asset management and O&M services. By combining module-level monitoring with our existing service offerings, we are able to offer different O&M packages—combining performance guarantees, extended warranties or other post-installation services—and have confidence that fielded systems are working and will continue to work as expected. With robust reporting and energy data analytics, module-level monitoring can eliminate false alarms and minimize truck rolls to actual reactive work.”

Lior Handelsman / SolarEdge / Fremont, CA /

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