Top positive review
23 people found this helpful
But you have the same issue with string inverters in terms of bad connections, dead panels
on March 25, 2015
I don't want to repeat what others have said but I will fill in a few gaps based on real world use. I have a 15.3kW roof mounted installation consisting of 68 Qcell Q.base 225 panels. The most any panel has ever put out in the Texas sun is 205 W but my panels are on two faces of the roof, one facing a bit to the SE, another to the SW. AFAIKT, the derating for not having perfectly south facing install is only a few percent. For my install, I used the M215s. As one comment said, yes, they are difficult to get access to and on my roof they are packed tightly to get all 68 panels up there. And so yes it would be some trouble to service a dead inverter. But you have the same issue with string inverters in terms of bad connections, dead panels, etc. The huge advantage of the M215 is the monitoring SW called Enlighten. Using this can can tell what the entire array is doing with 5 minute resolution. If any panel is bad, I will know it right away. This makes debugging a SNAP and more than makes up for having the inverter buried in a roof array. Would ground mount be easier? Perhaps. But my cable runs are short and I don't lose real estate by having roof mount. Also, the panels absorb a lot of the energy that would have hit my roof. So my shingles will probably last longer and my attic is a bit cooler.
My friend put in a 30kW ground mount, same panels. But he used string inverters. He instrumented the whole thing with eGauge at extra cost. We find that between his optimally positioned array that uses Sunny Boy string inverters and my non optimally positioned array that uses M215 that the performance per panel is about the same. So anyone talking about "efficiency issues" is just presenting theory which I find in actual practice to be baseless. The cost of an M215 equipped setup was about 30% more in the in the inverter department (including special cables from Enphase that are needed and are not cheap...) but again, it was very easy to debug and I will have simplified maintenance going forward.
One of the things you have to know which is important IMO is that if the grid goes down these inverters do not support an "island mode". I think that is a safety cop out.You should have the ability to disconnect from the grid and then have to send some special command sequence to enable island mode. What if a storm takes out all the power and it is out for weeks on end including at your house even though you paid for inverters? That would suck but that is how it will be with these inverters. There really out to be a special interlock switch option that, when the grid is locked out, enables island mode.
Bottom line, I am very happy with everything about these inverters after 1 year of operation in the TX heat and humidity.