Togo Micro Inverter Quality Assurance

Some tests applied to PV modules adapted for use in inverters are for mechanisms in PV modules, without a clear analog mechanism in inverters. Applied safety standards for PV inverters provide a rudimentary level of reliability testing, insofar as they relate to safety.

Additionally, the inverters need to withstand humidity when the cabinet doors are open, and be resistant to hail damage. In summarizing the status of standards for PV inverters, there is no generally applied design and type approval test for PV inverters at this time.

Design qualification tests cover infant failure and an extent of general usage, but do not typically have end-of-life wear out mechanisms covered within their scope. At this time, safety standards such as UL 1741 and IEC 62109 series are more developed for inverters, compared to those for reliability and quality.

Better quality is expected from tests that validate interfaces (e.g., the inverter/transformer interface), with sufficient sample size of fielded beta units with performance tracking to foster learning cycles, and improved manufacturing controls to catch errors on the production line.

The inverters constitute between 43% and 70% of the PV power plant service requests as seen in Fig. 1. Financial losses additionally accrue due to energy losses. The inverter has been reported to be the greatest factor leading to energy outages, responsible for up to 36% of the energy loss .

The cost of O&M work necessitated by inverter failures influences the profitability of PV installations. The inverters constitute between 43% and 70% of the PV power plant service requests as seen in Fig. 1. Financial losses additionally accrue due to energy losses.