In today’s world, electricity is the lifeblood of countless industries. Inverters play a crucial role in ensuring a steady and efficient power supply. Regular maintenance is key to preventing unexpected shutdowns and regular operation at peak efficiencies.

What is an Inverter?

A solar inverter system converts the direct current (DC) energy from your solar power plants into usable alternating current (AC) electricity for your home’s appliances and electronics. If the solar inverter fails, your home won’t get the solar-generated electricity, potentially resulting in unexpectedly high utility bills as you unknowingly draw power from the grid.

Learn how to maintain your solar inverter system to prevent issues and what steps to take if you require solar inverter service or repair. This guide provides crucial insights into solar inverter preventive maintenance, repair, and service, emphasizing the pivotal role of the inverter in your solar power plants.

Importance of Preventive Maintenance of Inverter:

Preventive maintenance of solar inverters is very important, as any kind of negligence can lead to severe consequences. There are several factors, such as faulty installation and design, consumables (e.g. fans, fuses, breakers, and switches), exposure to heat humidity, and lastly, failing to put in an effective maintenance strategy that affect inverters performance.

Monthly Inverter PM Checklist

Below are the detailed steps for an inverter’s monthly preventive maintenance checklist.

Visual Inspection:

In visual inspections, as a first step, you must check for any physical damage the inverter must have. For example, we need to inspect the cables and wiring for signs of wear, damage, or loose connections. A visual inspection could be inspecting the inverter from the outer and inner covers, as shown in Figure 1.

Visual Inspection

Environmental Conditions:

Besides monitoring the ambient temperature and humidity around the inverter and ensuring that they work under the specified limits, several other tasks can also be performed.

  1. Set temperature thresholds as an upper limit; normally, it is 40-50 degrees Celsius, and use a temperature sensor.
  2.  Check that the inverters have efficient cooling systems such as fans.
  3. Use humidity sensors to measure humidity levels and also set an upper limit threshold.
  4. Ensure insulations and enclosures of the inverter.
solar inverter supply flow

There are a lot of wiring systems and devices involved in connecting the inverters with panels and household systems, as can be understood from Figure 2, so considering proper environmental conditions is an important step to ensure the proper operation of inverters.

Cleaning 

Remove dust and debris from inverters, as this will affect its efficiency. Also, check insect guards at the inlet and outlet.

Status Indicators:

Some of the status indicators and their working principle used in inverters are mentioned below:

Run/Standby Indicator:

This indicator indicates whether the inverter is in “run” mode(operational) or it is in “standby” (not operational) condition.

Output Voltage and Current Indicator:

    In this indicator, the real-time voltage and current are detected and displayed.

    Frequency Indicator:

      This indicator shows the output frequency of the inverter displayed in hertz(HZ).

      Alarms and Logs:

      • Overcurrent Alarm:

        This alarm is triggered when the current above the specified threshold flows through the inverter.

        • Over/Under Voltage Alarm:

          Activated when the output voltage exceeds or falls below the specified limit.

          • Over Temperature Alarm:

          This alarm is activated when the inverters’ internal temperature exceeds limits.

          • Ground Fault Alarm:

            Triggered when a ground fault is detected in an electrical circuit.

            • Emergency Stop Alarm:

              They are activated when an emergency stop button or switch is pressed, shutting down the inverter immediately.

              Battery Checks:

              To assess battery performance, we can use the following steps.

              • State of Charge (SoC):

                This represents the charge remaining in the battery, expressed as a percentage.

                Typical values: Fully Charged Voltage is around 12.6-12.8 volts, and Discharge Voltage is around 11.0-11.5 volts for a 12-volt battery.

                A healthy battery should have a SoC close to 100% when fully charged.

                • Load Test:

                  A load test can be conducted by applying the known load to the battery and measuring how long it can sustain it before the voltage drops.


                  Capacity=load current * discharge time(h)

                  • Internal Resistance:

                    Lower internal resistance indicates better battery health; we can check the resistance using a specialized battery tester.

                    • Voltage Recovery:

                      After applying the load to the battery, check how quickly it recovers to its resting voltage when removed.

                      Communication and Monitoring:

                      Test communication interfaces (e.g., Modbus, Ethernet) to ensure data transfer to monitoring systems is functioning properly.

                      Safety Precautions: 

                      1. Ensure that a work permit is issued.
                      2. The engineers responsible for inspection follow all the safety protocols.
                      3. Ensure that the workers are wearing personal protection equipment.

                      Conclusion:

                      In conclusion, a thorough monthly preventive maintenance checklist of an inverter in a solar power panel system is important to ensure the reliable and efficient operation of the entire solar power plant.

                      Some important takeaways are:

                      1. Prioritize safety by confirming the work permit.
                      2. Monitor the temperature and humidity conditions to keep up with environmental considerations.
                      3. Regularly inspect the inverter.
                      4. Keep the inverter and its surroundings clean to prevent dust.
                      5. Battery checks
                      6. Documentation.
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