Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) explained the importance of maintenance/inspection of PV inverters for stably operating mega (large-scale) solar power plants for a long period of time at the maintenance/inspection seminar that the company had in Tokyo, Fukuoka and Osaka in mid-September 2017.

TMEIC recommends its customers to conduct "precise inspection" in the sixth year after the start of operation.

In Tokyo, in view of the fifth year after the implementation of the feed-in tariff (FIT) policy, the company said, "In addition to annual inspection, TMEIC recommends precise inspection every five years. Professional engineers from PV inverter manufacturers make a diagnosis and repair and replace parts so that the PV inverters can surely operate stably for the next five years. Also, in the project plan certification system that was introduced for the revision of the FIT policy, the planning and implementation of appropriate maintenance are required."

Next, TMEIC explained about the specific inspection schedule and the contents of the precise inspection.

The maintenance of PV inverters consists of "daily inspection," "periodic inspection" and "precise inspection." The daily inspection is a daily visual check done by a power producer. The periodic inspection is conducted every year and includes not only an appearance check but also a functional check that is conducted by stopping the operation of PV inverters.

The precise inspection is conducted every five years. The operation of PV inverters is stopped, and engineers from manufacturers diagnose the state of the equipment and replace expendable parts.

For the precise inspection, air filters and cooling fans are replaced in the sixth year after the start of operation. And if TMEIC's enclosure is used, the UPS (uninterruptible power-supply system) and enclosure caulking are repaired. In the 11th year, LCD panels, fuses and air conditioners are added to the list. In the 16th year, electrolytic capacitors are added.

"The number of mega solar plants that we recommend to carry out the precise inspection will drastically increase this year," the company said. "Defining the year 2017 as the first year of precise inspection, TMEIC will actively explain its importance to our customers."