I installed a solar system in 2020 and expanded it in late 2021. The results have been very good so my neighbors all got quotes from the same outfit that installed mine and asked for my help. Coincidentally, ENPH was being bandied about this board. As I researched ENPH and read some of the remarks elsewhere in Fooldom that mentioned the huge advantage ENPH had because microinverter technology could produce optimal results over the competing string and central inverter setups, I was confused because I knew I had a string setup, but had the ability to see electrical output on a per panel vs. string basis.
Turns out, there are three competing technologies - string (cheapest and least flexible), string plus micro optimizers (offsets disadvantages of string only setups) and micro inverters ( most flexible, ENPH uses). So I called my solar outfit and asked if my neighbors were getting a microinverter system. The answer was yes. I voiced my concern about my system having old technology after just a year (I did not know about the micro optimizers at that point). I was told that the reason I could see individual panel output was due to the micro optimizers and my system was preferable to a string only system.
I then asked specifically about ENPH and was told “to be honest, we have totally switched over from Solar Edge to ENPH from top to bottom.” Why? The micro inverters were part of the story, but another important consideration was related to transporting DC current in the house. Building codes vary, but in our locale, DC current needs to be shielded with more expensive conduit than AC current. Since micro inverters convert DC to AC on the roof, it simplifies the installation process. Finally, the increased cost of micro inverters vs. micro optimizers is offset by not needing the central inverter in a micro inverter system. As ad15 pointed out, the micro inverter or micro optimizer systems are more expensive than a straight string only setup. However, unless all panels get the same exposure all day long (an unlikely scenario), these micro systems are preferable. Myself, I have three sets of panels and there is variability in exposure among the panels within each set owing to orientation and things like vent stacks and chimneys.
This boots-on-the-ground research, in addition to the excellent discussion above, led me to take a position in ENPH.