Thursday, September 12, 2019

Failing 1st generation microinverters

10 years ago when I began installing my solar power system, I was one of the first to use the new technology of microinverters made by Enphase(Details of my installation here).  These are small devices that convert DC solar power to 240VAC in a small box mounted behind each panel.  Original model shown above, and new one shown below.

I was a very early adopter, mine was the 1239th system commissioned back in 2009.  Now there are millions of systems, and they are up to 6th generation technology. The devices come with a 15 year warranty and I'm at the 10 year mark and have just replaced the 7th failed unit out of a total of 32.  I am able to see which ones failed from the web interface that reports performance in near real time.

It is a chore to climb up on the roof with a friend and 2 long ladders.  We have to remove the 30lb solar panel, set it aside, remove the failed microinverter and replace it, then replace the solar panel.  It takes up to an hour to do this safely and carefully.

What I really like about this system is the granularity.  I can see the performance of the system on a per-panel basis and failures are easy to spot.  And I can scroll through the recent day or week to see how the system is performing.  Below is overall power for the last week with peaks at around 4kW.

I'm hoping that Enphase will continue to replace them if units fail after the 15 year warranty.  Despite these setbacks, the system is performing very well and I am powering my home, workshop and Chevy Volt for free for up to 7 months of the year.

The pattern of failures is interesting, they seem to propagate over time: