From time to time, parts of the array may stop working; that is, produce no electricity. The principal points of failure are:
My experience after five years of production shows that the most likely thing to fail is an inverter, followed by the cabling back to the meter. There has been no failure of any other part of the system.
Let's deal with the cabling first. This was a simple matter of a blown fuse. The issue was never exactly explained, however the fuse was located behind a protective plate which was very loosely screwed into place. The failure happened during a rainstorm, and the probability is that water or simply dampness penetrated inside the pole and caused a short. It happened in the first week after the installation and has not happened again. After the replacement the covering plate was firmly secured into place.
Really the only part of the system which has caused concern is the Enphase D380 dual inverters. The inverter is a dual since it takes the power produced by a pair of panels. In fairness I should add that Enphase has, over time and based on customer feedback, recognized that this particular inverter has problems and they have been willing to replace the units under warranty. The manufacturer has decided to discontinue manufacture of this inverter model and replace any failed units with a kit consisting of a pair of single inverters, each inverter serving a single panel.
The history of my system is that I started with 24 dual inverters handling 48 panels. Over the next 3 years the duals failed at the rate of two or three a year and were replaced by new duals at no cost to me. "Failed" here means stopped reporting to the central Envoy controller, and in one case stopped producing power. In the last year the failing duals have been replaced with a kit consisting of two single inverters. I currently have 17 duals remaining, the rest of the 7 locations being occupied by the replacement kits.
Economic costs to me of these replacements are the expense of monitoring for failure, contacting a technician, arranging for replacement and paying any extra cost incurred by the contractor over and above the amount paid in compensation by Enphase to the contractor. The contractor arranges all shipping and handles the technical details of installation and performs the work in a professional manner ensuring that the new situation complies with Enphase warranty and Ontario Hydro safety and grid standards.