The solar market in the United States is in a much different state today than just a few months ago. At the beginning of 2021, there was excitement surrounding the projected growth of the domestic solar market. A big reason for that excitement was the potential for increases in tax credits and government funding if projects utilized domestic content for the sourcing of major components. This domestic content would create additional demand for production to be onshored so the industry could start to move away from a supply chain that is mainly overseas.

In February 2022, however, the solar market was dealt an unexpected blow. California-based Auxin Solar filed a petition with the U.S. Department of Commerce alleging imports of solar cells and/or modules originating from Cambodia, Malaysia, Thailand and Vietnam were including/incorporating Chinese-made parts and evading U.S. tariffs on Chinese products. Whether the allegations have merit is uncertain, but the Commerce Department has promised to investigate the claims. Meanwhile, imports of crystalline silicon panels and components from Southeast Asia are now on hold.

The uncertainty created by the tariff investigation, coupled with increasing costs for materials, labor and transportation, has increased the capital cost of new solar installations. At the same time, pressure to reduce carbon emissions remains high. As a result, solar companies’ time and resources can be refocused on the performance of their established photovoltaic (PV) systems to see that they are operating as designed. If they aren’t, this is a good time to consider improvements, replacements and upgrades.

Performance Analysis of Existing Solar Projects

A thorough understanding of how a company’s PV assets have performed over the past five to 10 years versus their modeled performance can be obtained in several steps. First, a high-level performance analysis would determine whether the solar installation as a whole is performing above or below expectations. That determination could come from a review of the supervisory control and data acquisition (SCADA) system data, design drawings, bill of materials or equipment lists to understand the project from a design perspective.

Next, if any underperformance is found, an in-depth analysis would identify which specific aspects are underperforming. That could include the PV array’s energy production, the tracking system’s uptime, or the inverter’s performance and reliability. That deeper understanding could also identify outside impacts such as curtailment from the grid operator, wherein the site is operated at a lower power level than it is capable of generating.

Next Steps: Fix, Upgrade or Replace?

Today’s solar industry is a lot more competitive and operates at a lower cost than it did just a few years ago. During the performance analysis, discussions between the engineers conducting the analysis and company leaders will focus on several questions:

  • What do the project owners like, or dislike, about the current system?
  • What would they want to add or upgrade?
  • If a component is not working, can it be fixed or does it need to be replaced?

PV system underperformance can be caused by a variety of factors, but excessive PV module degradation, tracker downtime and inverter reliability issues are some of the most common factors that directly affect a solar installation’s energy production.

Understanding the performance of the PV modules can be achieved through on-site and laboratory testing. On-site testing can be accomplished with a drone flyover utilizing an infrared camera to detect abnormalities in the PV array. The flyover can be used to identify underperforming strings of PV modules or hot spots on certain modules that could be attributed to an internal module defect or partial soiling of the PV modules. If a solar installation’s PV modules are not performing as expected, the owner could choose to further investigate the underperformance with the PV module manufacturer and replace bad modules covered by the warranty.

Tracking system downtime could be caused by issues with the mechanical and electro-mechanical systems as well as the tracker control system. Also, some tracking manufacturers have exited the PV industry, so there may be limited warranty support available for those systems. An engineered solution could be required to remediate mechanical issues, upgrade motors or replace the tracker control systems.

Inverter performance issues can be caused by overstressed components such as the insulated gate bipolar transistors (IGBTs), fuses, disconnect switches, contactors, breakers, cooling systems, or general environmental (temperature, humidity, dust, etc.) stresses on the system. Similar to tracking system manufacturers, some inverter manufacturers have exited the PV inverter industry, limiting or eliminating support remaining for the equipment in the field. As product warranties expire, project owners can be left with the tough decision to purchase extended warranties (if available), spare parts or entire inverters.

Inverter repowering is another option where an engineered solution can be developed to replace the existing inverters with new inverters while repurposing as much of the existing balance of plant as possible. This often involves replacing what was a central inverter 10 years ago (500-1,000 kVA each) with a few string inverters in today’s market (100-250 kVA each.) An in-depth analysis is required to verify compatibility between the existing PV array, which is likely 600 Vdc or 1,000 Vdc, and today’s utility scale inverters, which are typically 1,000 Vdc or 1,500 Vdc models.

Companies that quickly built out their portfolios using different contractors over the years probably have different equipment and/or SCADA systems at their sites. As a result, owners’ operations and maintenance (O&M) teams are likely stuck operating different projects sites with differing SCADA systems and associated HMIs, which can lead to inefficiencies and inconsistencies across a portfolio. For inverter repowering, the SCADA system would require additional upgrades regardless, which gives the owner the opportunity to standardize its portfolio utilizing similar SCADA platforms to give the operators a consistent experience while operating, maintaining and troubleshooting installations in the owner’s portfolio. Consistent SCADA system platforms and interfaces can benefit the O&M teams by enabling quicker identification of performance issues and alarm investigation, leading to improved plant performance and energy yield.

The Bottom Line

High costs, material availability and uncertainty in the solar market are making new projects challenging. At the same time, pressure to reduce carbon outputs continues to build. Therefore, as the Commerce investigation drags on, focusing on a performance evaluation and improvements to companies’ existing PV sites could yield financial and carbon reduction benefits.


Utilizing an integrated EPC partner is imperative to creating a more seamless, predictable and cost-effective solar and energy storage project.

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Grant Reasor is a senior electrical engineer experienced in the solar photovoltaic (PV) industry. His background includes the design, testing, commissioning and troubleshooting of utility-scale PV inverters.