Solar O&M Priorities: Top 7 Items to Inspect and Maintain Frequently for Proactive Maintenance

Solar energy systems are often viewed as a sustainable and low-maintenance power-producing asset. However, in reality, the sustainability and long-term performance of solar assets are heavily dependent on proactive inspection and maintenance. Even systems that are well designed and built can begin to suffer in the early years of operation from a lack of proper O&M (Operation & Maintenance) activities.

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Consistent and thorough maintenance is what turns solar assets into a reliable, revenue-generating system for decades. Without proper O&M plans in place, performance slowly degrades, risks increase, and small issues turn into expensive repairs.

Since most solar failures don’t happen suddenly, but instead gradually, catching problems early is essential. An O&M plan that covers routine inspection and maintenance, especially of the most common failure points in a system, is guaranteed to optimize performance, safety, and longevity of any solar asset. Here are the top items to prioritize on any solar site:

1.   Inverters

Inverters are often looked at as the heart of any solar system, converting DC power into usable AC energy. If inverters experience issues and go offline, they immediately impact production. That is why a proactive maintenance plan is essential and can address overheated components, ventilation and cooling systems, loose electrical connections, fault codes, firmware updates, and more.

Inspection Frequency: Frequency depends on site conditions, equipment type, and warranty requirements, but a good starting place is visual inspections monthly to quarterly, and preventative maintenance tasks every 6 -12 months (torque checks, thermal imaging, replacing air filters, firmware updates, etc). At a minimum, a full inspection with follow-up testing and repairs should be performed yearly.

1.   Switchgear

Switchgear plays a vital role in ensuring the stability and safety of electrical distribution in solar energy systems. Switchgear protects equipment from damages caused by overloading and faults. Lack of maintenance on switchgear can increase the risk of arc flash incidents, overheating, equipment damage, and sudden substation outages, which means large portions of a site going offline instantly.

Inspection Frequency: Similair to inverters, visual inspection of switchgear is recommended quarterly, or based on site conditions. Preventative maintenance tasks should be performed every 6-12 months, such as torque checks, cleaning of busbars and compartments, breaker checks, and inspections of insulation and barriers. It is recommended that more comprehensive electrical testing be performed annually, such as Insulation Resistance Testing (IRT).

2.   Combiner Boxes

Combiner boxes are easy to overlook—but they’re one of the top common sources of faults on solar sites. Common combiner box failures include blown fuses, loose connections, water intrusions, degraded surge protection devices, corrosion, and damaged insulation

Inspection Frequency: Quarterly visual inspections to check for moisture intrusion, dust, pest interference, burn marks, or loose conduit. Then, preventative maintenance tasks every 6-12 months, such as torque checks on all terminations, fuse replacement, wire management, etc. Annual systemwide IV curve tracing, insulation resistance testing (IRT), and thermal inspections can detect many issues found with combiner boxes.

3.   Panel Boards

Panel Boards are where AC power is split, protected, and delivered across a solar site—often feeding inverters, auxiliaries, trackers, and balance-of-system loads. They don’t get as much attention as inverters or switchgear, but failures here can still shut down sections of a system or create serious safety risks. Breakers here prevent overloads and fires. Poor connections in a panel board can cause widespread issues.

Inspection Frequency: Quarterly visual inspections to look for dust and moisture intrusion, wear on breakers, loose conductors, or signs of overheating. Every 6-12 months perform preventative maintenance tasks such as torque verifications on all lugs and terminations, cleaning of busbar, checking breaker operation, inspecting grounding, etc. Annual electrical testing such as thermal imaging, insulation resistance testing, and load verification, makes sure all major components, such as panel boards are performing as excepted, with no safety threats.

4.   Transformers

Transformers on solar sites are critical equipment to step up or down voltage levels, making energy transmission to the grid possible. Transformers must withstand various environmental conditions and are expected to operate for extended periods of time. If a transformer fails, you are not just losing efficiency, but entire blocks of generation, so rigorous testing is essential. A maintenance plan that includes periodic visual inspections, testing, and servicing is expected to maintain optimal performance.

Inspection Frequency: Like most of the system, visual inspections as often as possible or quarterly is the first line of defense, by looking for cracks, leaks, corrosion, or unusual noises or vibrations. Every 6-12 months clean bushings, perform torque checks, service cooling systems, and verify grounding connections. Annual servicing and testing, such as dissolved gas analysis, oil testing, TTR testing, thermal imaging, insulation resistance testing (IRT), fuse assembly checks, etc. are all used to make sure transformers are operating safely and can perform without failures.

5.   Wiring and Connections

Solar energy systems are complex electrical systems with wiring and electrical connections being made at all critical points in the system. Wiring and connection integrity can affect every major component of systems, including combiner boxes, inverters, switchgear, transformers, and more. Proactive inspections, wire management, and routine electrical testing of connections are essential for safety, performance, and system longevity. Loose or poorly crimped connections cause resistance and heat that can lead to arc faults. This is one of the leading causes of electrical fires on solar sites. Poor connections and wiring issues can also lead to inverter and combiner faults, which can take portions of a system offline.

Inspection Frequency: Quarterly visual inspections to look for exposed, loose, or damaged wiring, cracked insulation, proper wire management, and rodent or environmental damage. Every 6-12 months perform torque verification on all terminations, replace degraded connectors, perform systemwide wire management, etc. Annual systemwide testing of insulation resistance testing (IRT), IV curve tracing, and thermal imaging are great tools to find issues with wiring and connections.

6.   Modules

Modules are at the front-line of energy production and usually the first consideration when it comes to maintenance. While there is no argument that solar panels must be inspected and maintained, the maintenance plan can change drastically based on the region. For example, hot dessert regions may need routine panel cleaning more often than areas that receive a lot of rain. However, there are more threats to solar module production than just dirt and dust. Modules are constantly exposed to external and environmental stress, as well as degrading over time. Hotspots, microcracks, diode issues, discoloration, bird droppings, hail, and other events can all pose a threat to module efficiency and must be routinely checked. 

Inspection Frequency: Depending on system size, visual inspections can be performed whenever on site to check for dirty modules, damage, and module shading. However, the best way to quickly inspect all modules is through a thermal inspection, performed by drone 1-2x a year. Not only can this type of inspection detect anomalies not seen to the plain eye, but can quickly inspect all panels in the system, efficiently and quickly.

Solar energy systems are designed for long-term performance, but peak performance is never reached if a strong O&M strategy is not in place. At Day Electric, we believe the best strategy is consistent and routine inspection and maintenance tasks. It starts with visual inspections with a knowledgeable technician and is followed up by biannual or annual inspection and testing measures. When the “small issues” are constantly getting tackled and resolved, emergency visits, downtime, or large repairs are needed less. The most successful solar operators understand that proactive maintenance, performed by quality technicians, isn’t an avoidable expense—it’s an investment. In an industry where performance directly impacts revenue, proactive inspection and maintenance is the difference between a system that simply operates and one that hits peak production goals year after year.

About Day Electric:

Day Electric is an independent solar service provider offering a variety of inspection, testing, repair, and maintenance services to support owners, operators, and developers with commercial and utility-sized solar projects.

As solar projects continue to expand across the United States, partners like Day Electric play an important role in helping developers, EPCs, and asset managers deliver high-performing, reliable solar assets. To learn more, visit: https://www.dayelectricusa.com/solar