The Importance and Methods of Maintenance and Repair in Solar Power Plants

Maintenance and Repair Methods in Solar Power Plants

As of September 2018, the installed capacity of solar power plants (SPPs) in Turkey has reached 4,849.7 MW. Of this capacity, only 81.7 MW comes from licensed plants, while a significant portion—4,768 MW—comes from unlicensed solar power systems. Considering that unlicensed plants are limited to a maximum installed capacity of 1 MW, it can be assumed that there are at least 4,768 independent projects, each with its own transformer. This clearly indicates a substantial potential for system malfunctions and failures.
Most of these solar plants have been installed within the last two years, and the EPC warranties of at least 4,700 plants totaling 4.7 GW are nearing their expiration (typically 2–3 years).
At Maxima Enerji, we foresee that serious technical issues may arise for solar investors in the near future. In light of this situation, we have prepared a research article exploring:

• The potential technical problems,
• The risks these problems may pose, and
• The necessary preventive measures that should be taken to eliminate or mitigate these risks.

Common Failures in Solar Power Plants and Maintenance & Repair Recommendations

Insulation Faults

Insulation faults are among the most frequently encountered issues in solar power plants. These faults are typically caused by improper or loose connections made during the EPC (Engineering, Procurement, and Construction) phase, over-tightened cables, or sharp cable tray edges damaging the cable insulation. Additionally, rodents gnawing on cables can lead to serious insulation damage.
Such faults often result in short circuits, which in turn can cause inverters or other connected devices to malfunction or shut down entirely. After addressing the fault, an insulation test must be performed in accordance with the IEC 62446-2016 standard. Cable insulation resistance values should be at least 2 MΩ, and the measurements should be consistent across all cables.
If damaged cables are underground, they must be replaced by laying new ones. For above-ground cable faults, on-site repairs may be sufficient. During the winter months, rodents tend to shelter in underground channels and often build nests near warm cable conduits. This can lead to DC cable damage due to rodent activity.
As part of maintenance and repair practices, rodent control and pest management must be implemented on-site to mitigate such risks and prevent recurrence.

Inverter and Compact Circuit Breaker Failures

Inverters are among the most critical components of solar energy systems, as they are responsible for converting direct current (DC) into alternating current (AC). The maintenance and repair of inverters should be conducted in accordance with the maintenance manuals provided by the equipment manufacturers.

Depending on the brand, there may be differences in inverter mounting connections and ventilation systems. For string inverters, improper or untorqued electrical connections can lead to terminal burns over time. In central inverters, annual maintenance of air filters and fans is essential. Additionally, proper ventilation, cleaning, and maintenance of the inverter station are crucial for system efficiency and longevity.

Overheating problems in circuit breakers used in solar power plants typically stem from poor or degraded electrical connections. These issues can only be prevented through regular and proper maintenance.

To minimize the risk of fire and reduce potential energy production losses, it is vital to perform thermal imaging inspections and visual checks of all electrical connections at least once a year across the entire solar plant.

 

Solar Panel and Solar Connector Failures

The most frequently observed problems in solar panels are hotspots on cells, diode failures in junction boxes, and cable faults inside the junction boxes. These issues, especially during summer months, often cause panel efficiency to fall below nominal performance levels.

Another common fault is connector mismatch, which occurs when incompatible connectors are used together. This mismatch can lead to connector failure, resulting in burned connectors that pose a significant fire risk to the solar power plant.

Such problems can be identified and resolved through periodic (preventive) maintenance. During preventive maintenance, thermal imaging must be conducted in accordance with IEC 62446-2016 standards and by qualified personnel. Otherwise, incorrect analysis may lead to misleading conclusions and potentially overlook serious faults.

Medium Voltage (Transformer, Circuit Breaker) Failures

Failures in medium voltage (MV) systems, which connect solar power plants (SPPs) to the grid, can lead to significant production losses. In particular, the repair or replacement periods for transformers and circuit breakers can take up to a month, highlighting the magnitude of the risk.

To prevent such failures, periodic maintenance must be carried out by qualified personnel. During maintenance, testing of transformer protections is of critical importance. Transformers without proper protection are vulnerable to phase faults caused by voltage surges or disturbances from the grid. In the event of phase burns, the transformer usually needs to be sent to the manufacturer for repair.

For oil-filled transformers, it is recommended to conduct:

• Dissolved gas analysis (DGA),
• Turn ratio measurements, and
• Winding resistance tests.

In circuit breakers, measuring contact resistance is essential to detect potential arc formation early and avoid serious failures.

Failures Due to Relay Coordination Issues

Relays are essential components in power systems, designed to protect the system against abnormal operating conditions. If the quality of energy supplied from the grid or within the system deteriorates beyond acceptable tolerances, it can cause serious damage to equipment. To prevent such issues, relay coordination must be properly implemented in the field.

Without proper relay coordination, voltage surges or disturbances coming from or going to the grid can lead to unexpected faults and even explosions. The effectiveness of the hierarchical protection mechanisms (circuit breakers, relays) in response to grid disturbances can only be evaluated by checking whether the relay settings are correctly configured and if the protection devices operate according to the coordination plan.

In addition to the failure types outlined in this article series, dozens of other failure scenarios can occur in solar power plants (SPPs). Based on our experience, we have highlighted the five most common types of failures here. The underlying cause of almost all these failures is either the lack of professional preventive maintenance or maintenance performed by unqualified personnel not in compliance with industry standards.

Solar power investments are long-term assets, expected to generate income for investors over a minimum period of 25 years. During this period, effective maintenance and repair services not only prevent financial losses due to faults but also help maximize energy output, making the investment more profitable and shortening the return on investment period.

Therefore, investors should not see maintenance and repair activities as a cost, but rather as a strategic investment that protects assets and potentially increases returns. Otherwise, neglecting proper maintenance may lead to more severe and costly failures, requiring significantly higher budgets for repairs.