Enphase M250 vs M215 Microinverters
New M250 (72) - The newest Enphase M250-72 is a fifth generation micro-inverter. Optimized for solar panels with 60-72 cells and up to 320w these are the most cost effective in the industry presently. Of course it includes all prior advancements like integrated grounding. And finally, it continues to carry the industry leading 25 Enphase Warranty.
M250 - The Enphase M250 is Enphase's new fourth generation micro-inverter. Optimized for solar panels from 210-300w it has the highest efficiency in the industry. It also simplifies installation with the addition of DC circuit isolation, no separate ground is required during installation. CEC rated efficiency is 96.5%.
M215 - The Enphase M215 is Enphase's flagship third generation micro-inverter. Optimized for solar panels from 190 - 260w it has almost the same efficiency as the M250 micro-inverter. It also simplifies installation with the addition of DC circuit isolation, no separate ground is required during installation. CEC rated efficiency is 96%.
Both - Both microinverters carry Enphase's industry leading 25 yr full replacement warranty and remote monitoring using the Enphase Envoy. Both are compatible so you can even mix them on the same AC trunk cable.
An important note: CEC efficiency ratings can be misleading. Most laymen would not understand what it means but unfortunately most of the industry uses this and it can create unrealistic expectations.
In fact, both the M250 and M215 have a "derate factor" of .82. This means that you will get 82% of the DC power output as AC power. So to most of us this means 82% efficiency in converting DC to AC. For example, an M215 connected to a 260w panel will produce 260 * .82 = 213w AC. Similar math applies to the M250 except that the newest can produce up to 262W because 320 *.82 = 262.4.