10 Most Common Production Issues on Commercial Solar Sites that Affect Site Performance (and How to Detect Them)

Discover the 10 most common production issues on commercial solar sites — from inverter faults to shading and soiling — and learn how proactive inspection and monitoring can maximize solar site performance.

Commercial solar systems are designed for durability and consistent energy generation. Yet, even with the best equipment and design, performance losses are inevitable over time. Whether caused by lack of maintenance, electrical faults, or monitoring failures, these production issues can reduce output — and profits — if left unaddressed.

Here are the 10 most common production issues found on commercial solar sites and how to most efficiently detect them.

1. Offline Inverter

When an inverter stops working, production from the connected array section ceases instantly.

Detected by: Visual inspection or thermal drone inspection, which can quickly identify inactive inverters through heat signatures and temperature differentials. Offline inverters are often detected through the DAS monitoring system, and monitoring team is alerted.

2. Offline String or Combiner

A single offline string or combiner box can cause noticeable generation losses.

Detected by: Visual inspection and drone thermography, which reveal inactive or strings that indicate a potential disconnection or fuse failure.

3. Grounding and Electrical Faults

Poor grounding or damaged conductors can create electrical hazards, equipment trips, and unplanned downtime.

Detected by: Sudden production loss or visible signs of electrical events and equipment failure.

4. Solar Module Defects

Modules can develop hot spots, cell cracks, or delamination over time, reducing energy yield.

Detected by: Visual inspection, handheld IR testing, and aerial thermal imaging to spot thermal anomalies or failed cells.

5. Connection and Wiring Issues

Loose or corroded connectors increase resistance and pose fire risks.

Detected by: Fluke meter testing or drone thermography to locate areas of excessive heat caused by poor electrical connections.

6. Shading

Shadows from nearby trees, overgrown vegetation, or buildings can cause uneven string performance and mismatch losses.

Detected by: Visual inspection or thermal drone inspection. Shading that causes production dips, will be detectable on DAS monitoring system as well.

7. Solar Module Soiling

Dust, pollen, and bird droppings reduce the light reaching the PV cells, often cutting output by several percent.

Detected by: Visual inspection and/or thermal drone inspection. Modules should be cleaned on a routine schedule based on climate and site conditions.

8. DAS Anomalies (Monitoring System Failures)

If the data acquisition system (DAS) goes offline, production issues can go unnoticed.

Detected by: Loss of site communications or missing performance data in the monitoring platform.

9. Poor Installation Workmanship

Improper cable routing, uneven torqueing, or weak mechanical connections can lead to long-term reliability problems. A site not built to design, or poorly installed, will usually face production issues once operational.

Detected by: Visual and Mechanical Inspection, as well as proper commissioning of the system.

10. Maintenance Gaps

Inconsistent maintenance schedules or unaddressed alarms can compound performance losses over time.

Detected by: Reviewing O&M logs and system alerts to find recurring faults or extended downtimes.

Proactive O&M: The Key to Sustained Solar Performance

The best way to prevent these production losses is through proactive operations and maintenance. Regular inspections, thermal drone inspections, and real-time performance monitoring allow small issues to be detected before they become major failures.

By identifying and resolving these common issues early, you will:

• Boost performance ratio (PR) and annual yield

• Extend equipment life

• Reduce unplanned downtime and repair costs

• Prevent safety incidents

• Improve long-term ROI

  
  

Conclusion

Commercial solar assets are valuable, long-term investments — but only if they perform as designed. By understanding and addressing the most common production issues early, you can protect performance, maximize uptime, and ensure reliable clean energy generation for years to come.

Do you need your site inspected for production loss?

Day Electric is a trusted solar service provider, offering a variety of assessment, testing, commissioning, repair, and maintenance services to owners, operators, and developers in the solar industry.

One of the most effective tools we use to detect production concerns is through drone thermal inspections, followed by visual inspections and other testing (if required to further diagnose an issue).

For thermal drone inspection services on your next project under construction or in operation, reach out to Day Electric at info@dayelectricusa.com.