What is the need for rigorous evaluation of the inverter in a power plant?

An inverter is the most complicated component of the PV plant and is the heart of the system.

It converts DC power output from the panels into AC current that can be fed into the grid or power appliances and directly influences the efficiency and reliability of a solar energy system.

The inverter also monitors and controls the output from the panels.

Inverter breakdowns can cause the entire power plant to remain non-operational and thus amount to significant generation loss. Throughout the world, the system downtime is very closely correlated to the inverter downtime and around 80% of power plant failures are associated with inverter issues.

Inverters, similar to household electronic appliances, comprise of electrical components. But unlike most household appliances, inverters are exposed to outdoor conditions and thus have to be absolutely robust in nature. Electronic components are extremely sensitive to dust and high temperatures and the quality of these components will pretty much define the lifetime of the inverters.

The most common cause of failure or malfunctioning for inverters is an improper installation, often a combination of not following the user manual recommendation and selecting inappropriate cable type, gauges or fuses. Initial issues with the inverter are most often related to this.

Another cause for inverter failure is the extreme temperature and weather conditions it is exposed to. As mentioned before, the electrical components in the inverter corrode and are subject to high stress when exposed to extreme conditions. A high-quality inverter, on the other hand, will be less likely to face issues because of this.

Furthermore, you might want to evaluate the inverter cleaning process and the ventilation facilities in the inverter control room.

You might want to check out the generation reports for the power plants to know what the issues for failure in the power plant were. If most of them are correlated with the inverter in the plant, you might want to consider allocation of resources for its replacement.

Although correct installation and maintenance can significantly prolong the lifespan of inverters, when failure does happen, there are a few routes you can take. Especially for older or obsolete models, it might be worth considering the purchase of a new inverter.

Also while evaluating the inverter performance, do check with the O&M contractor on the resolution time taken for the inverter repair. Most often, irrespective of the inverter brand, they are very likely to break down. So the biggest metric you want to know is the effectiveness of the manufacturer’s technical support. Immediate resolutions of faults and quick repairs should help you evaluate the inverter positively.

Lastly, do remember the significance of inverters with extended warranties. Inverters with extended warranties up to seven to ten years are a good investment and should be scored high while you evaluate inverters.

You might want to check out these questions on Solar Power Plant Evaluation-Components:

  • How well have the components been chosen?- Here
  •  Presence of local service support from component manufacturers?- Here
  • What have been the degradation rates in panels?- Here
  • What types of monitoring solutions are employed by the power plant?- Here
  • What kind of trackers is employed?How do you ensure its quality?- Here
  • Are the components suppliers in business?- Here
  • What are the warranty clauses attached to key components?-Here
  • Can you retrofit additional components to an existing power plant to increase generation? – Here