How to improve ROI in commercial solar systems

New Belgium Brewing has added 446 kW of solar PV to its Asheville North Carolina brewery (Courtesy New Belgium Brewing).

Contributed by Kleber Facchini, Director of Product Management, Commercial & Industrial, SolarEdge Technologies

The market is now looking at PV systems more than just as a source of clean electricity. PV systems are now seen as long-term investments that must be carefully managed to increase their ROI and bottom lines. As with all investments, the two main ways to improve a commercial PV system’s ROI are to increase energy production and therefore annual revenue, and to lower lifetime costs. Let’s take a deeper look at how this can be done in commercial PV installations.

Performance ratio (PR), is a common method to evaluate the efficiency of commercial PV sites. PR measures the difference in the actual and estimated potential solar energy outputs of a commercial PV site. The measurement is the percentage energy that the system produces from the potential energy, as determined by temperature and irradiance measurements. Operation and maintenance (O&M) activities are performed in order to bring the actual output closer to the theoretical potential output of the system.

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The planning and design process is the best way to increase system energy production. Plant designers and asset owners should consider which system can place more solar panels on the array (rooftop or ground-mounted) when comparing the available PV options. Standard systems can reduce the number of solar modules that can be placed on an array because they do not allow for different layouts or string lengths. There are also limitations due to natural obstacles or objects that partially block sunlight. Commercial PV systems that are designed to overcome these obstacles and allow for more modules in the system will be more profitable from day 1.

Maximizing power losses from module mismatch is another key way to improve a commercial systems’ reputation and increase system production. EPCs and system owners can make sure that commercial systems are future-proofed by implementing technology to reduce mismatch and aging loss and protect against unpredictable environmental changes, new obstacles (e.g. antenna erected or growing trees, etc.).), and factors such as soiling, uneven surfaces, irregular irradiance and self-shading under bifacial modules. Technology such as module level power electronics (MLPE), optimizes the DC power output per module and minimizes energy losses. Regardless of how much future losses can possibly be reduced, there is a chance that defective modules will still need to be replaced even with high-quality ones. Costs can be further reduced if a system can be replaced using any module on the market rather than relying on expensive stocking.

Powerflex developed the rooftop solar system of 2.4 MWDC for Medline, Tracy, California. (Courtesy: Powerflex)

At the O&M level, providing a fast response to any sources that cause decreased production is another important factor in improving system uptime. O&M can be a very costly endeavor with slow response times. The advent of cloud-based module-level monitoring systems that provide real-time alerts, remote troubleshooting and real-time detection has made O&M much more simple. Instead of O&M being a labor-intensive process of searching for “a needle in a haystack”, asset management teams can choose systems that provide targeted information so that the field crew knows where the issue is before they go to the field. This not only increases system uptime; it also improves the efficiency of O&M and potentially decreases costs.

Another factor when analyzing O&M solutions is to differentiate between two different types of O&M activities – preventative versus corrective. Preventative maintenance is designed to keep the PV system in peak condition and minimize system downtime. This usually requires an annual site visit to thoroughly evaluate the components of the PV system and check the system’s health. Standard systems require that every module be inspected to verify their proper functioning. This is a time-consuming, expensive, and inefficient process. In large-scale cases, this might require the use drones to inspect. It can also expose maintenance personnel to dangerous conditions like high voltages, heights, wild animals, and even extreme temperatures.

Maintenance personnel often discover latent problems during preventative maintenance activities that cause the system to produce less energy for a longer time. Corrective maintenance would be required. Corrective maintenance is performed after an issue has been identified and includes the actual repair process.

However, there is also an optional maintenance style – selective maintenance. Advanced monitoring systems, particularly module level monitoring, allow asset managers to receive alerts regarding system issues to help reduce visits to the site and the time spent on site. This type of monitoring enables O&M service providers to perform site analysis for the AC and DC systems of the plant and only dispatch field personnel when it makes sense. For example, with such module-level monitoring, if a module has a failed diode, then an automatic alert will notify the O&M provider. A screenshot of the module can be taken to help identify it and can be sent to the manufacturer to file a warranty claim. This means that during the next site visit, the O&M provider can take a module to replace the failed one, saving a field trip and positively impacting the O&M budget. This type of monitoring requires MLPE, which is not usually offered by third-party service. Additionally, any third-party monitoring service can increase costs and negatively impact the system ROI.

DSD’s 415.6 kW rooftop installation at the City of White Plains Sanitation Building. (Courtesy: DSD Renewables)

Optimizing revenue and costs can be directly linked back to the original inverter choice. In recent years, the inverter selection became renowned for its influence on BoS costs, but more recently it has been directly associated with system production and O&M expenses. This is because the inverter manages 100% of system production and can control O&M expenses. A DC-optimized solution that provides cloud-based module-level monitoring at no cost not only eliminates CAPEX costs but also reduces ongoing maintenance and increases system uptime. By taking advantage of selective maintenance, the plant O&M requires less time onsite and fewer trips. With rising labor costs, selective and remote troubleshooting which is enabled by module-level monitoring can dramatically reduce long-term O&M costs. These monitoring solutions can also provide reports on array performance such as panel degradation that are often requested for investors, banks, and utilities.

These factors make inverter selection more important for the continued health and production of a PV plant. As the market heats for the best inverter to improve a system’s reputation, each of these factors becomes increasingly important. Therefore, when planning a large investment like a PV system, it is crucial to understand how inverters can increase system revenue and decrease costs throughout the system’s lifetime.

About the author

Kleber Fachini, Director of Technical Marketing, Commercial & Utility, SolarEdge North America

Kleber has over 15 year experience in electrical engineering and product management in the utility equipment and renewables industry. As Director of Technical Marketing, Commercial & Utility, he is responsible for conceiving, defining, and launching all related products across the continent. He also oversees the applications engineering team, who work directly with SolarEdge’s installer partners.

Kleber is a champion of processes that leverage his team’s strengths, cultivate collaboration, and result in a positive impact on the customer. He has a Bachelor’s Degree in Electrical Engineering and a Master’s Degree in Power Conversion from the University of Wisconsin-Madison.