Failing first generation microinverters

I installed my first array of 26 solar panels back in 2009 using state of the art microinverters made by Enphase.  I was an early adopter of the new technology that has created a paradigm change in solar power systems.  Previously an array of solar panels was wired in to a single large inverter that converts DC power from the solar panels to 240VAC that feeds in to the building.  

Microinverters are mounted behind each individual solar panel.  This creates a granular system that allows precise monitoring of the power produced at each panel.  It also offers a more graceful failure mode, if a single microinverter or panel fails, the whole system does not go down as it would with a large central inverter.

Over the years several of these first generation microinverters have failed and Enphase have been very responsive about sending out replacement units, honoring their 15 year warranty.  Of the original 26 inverters, 4 have now required replacement.  More details here.

It is tedious to have to go up on the roof using 2 ladders with a helpful neighbor and remove one of the panels and replace the inverter below it.   I hope the replacements will last longer!  As an electrical engineer, I recognize that the electronics are operating in the harshest conditions of heat and cold up on the roof and clearly there has been a learning curve as they gather data from failed units and incrementally improve the design.