Solar Power Plant Evaluation – What are the O&M measures practised and the frequency of maintenance checks followed in the power plant?

The importance of O&M is often overlooked by many developers. Considering the fact that the plant has to generate returns over a period of 25 years, a good O&M contractor, a good monitoring system and above all, a very good O&M process is very critical for the success of the plant.

Like in any power plant, a solar PV plant requires the following types of maintenance

  • Preventive Maintenance (PM) which includes routine inspection and servicing of equipment which help prevent breakdowns and reduce energy yield losses.  PM is usually a scheduled activity.
  • Corrective Maintenance (CM) or Breakdown Maintenance (BM) includes repair of broken down equipment and is usually reactive in nature.
  • Condition-Based Monitoring (CBM) involves monitoring of equipment condition and plant operations on a real-time basis and addresses a potential problem at a very early stage to prevent downtime. This requires a robust plant performance monitoring system.

Now how do you know whether a good O&M process is in practice for the existing power plant?

Check with the O&M contractor to ensure that the following customs with respect to each power plant component is followed.

  • Module Cleaning

Cleaning the panels in order to get rid of dust and other debris accumulated over time is an absolute must. Cleaning the panels can be done either with normal water or gentle soap water. The panels are to be also checked for any sort of animal infestation or cracks and other mechanical defects .A cleaning routine of once every two-three weeks (this could be far less in a region blessed with high rainfall availability) is considered optimal for power plants locate in dusty areas.

  • Inverter Maintenance

Any sort of dust or dirt accumulation on the inverters needs to be removed. Usually inverters come with display interfaces. The output should be more or less continuously monitored by the O&M team. The maintenance team is to ensure that the there are no loose wires or cables from or to the inverters and also look out for any loose nuts or bolts once every month and clean the exhaust fans every day.

  • Cables and String Combiner Boxes

Visual inspection of all the cables and combiner boxes every week should be in place. This will ensure that any physical damage caused by external factors like rodents and loose cables are detected before significant harm is caused. Similarly, the visual inspection will detect any insulation failure in cables or corrosion issues in combiner boxes

  • Civil and Structural Sub-Systems

One of the tasks of the O&M personnel will be to make sure that the growth of shrubs and other vegetation are fully in control. This should follow as part of the routine inspection. As part of the routine inspection, the O&M personnel should also be able to check out any misalignment or bends in case of mounting structures.

  • Transformer/Switchyard Bay Inspection

Here the parameters normally checked for include transformer oil level, temperature, and pressure. The transformer oil is to be replaced in case of any decomposition. The maintenance frequency related to these should be once every three weeks.

  • Warranty Management

The O&M personnel should have a very clear understanding of the warranty terms from the suppliers.  They also need to know the type of defects or problems that are covered under warranty, the duration of the warranty and also the key personnel from the supplier with whom warranty claims can be taken up and enforced in a timely manner. Maintenance frequency does not apply to this.

  • Inventory Management

The O&M team should know very clearly the list of the spare parts available, their quantity at the site warehouse and the lead times for delivery of spare parts from the suppliers.

Over and above routine maintenance practices, the O&M team should know to respond to the alerts and analytics provided by the monitoring systems in place and should be able to quote a decent resolution time for faults that have occurred in the plant.

Also, do remember that a proactive O&M team can adequately prepare the power plant for extreme weather events by taking necessary precautions. Do not forget to check with the O&M contractor if he can cite any such circumstance where the O&M team has taken preventive control.

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