The M175 was their first product, released in 2008. It was designed to output 175 Watts of AC power, but is capable of up to 5% over that. The M175 was packaged in a relatively large cast aluminum box, similar to the boxes used on cable tv amplifiers seen on telephone poles. Wiring was passed through the case using compression fittings and the inverters connected to each other using a twist-lock connection. A limited number of M210 models, based on the same generation system, were also available for a limited time.

Due to a high level of failures the M175 was recalled and replaced by the M190 in 2009. The M190 offers a slightly higher power rating of 190 Watts (peaking to 199). The system was packaged in a much smaller case, this time filled with epoxy potting material to handle heat dissipation, and built-in cable connections replacing the earlier compression fittings. The system was otherwise similar, using the same connectors and cabling as the M175, and the two designs could be mixed in a string. Like its predecessor the M175 the M190 has also been plagued by a high failure rate.

Around the same time the company also released the D380, which was essentially two M190’s in a single larger case. For small inverters like the M190, the case and its assembly represented a significant portion of the total cost of production, so by placing two in a single box that cost is spread out. The D380 also introduced a new inter-inverter cabling system based on a “drop cable” system. This placed a single connector on a short cable on the inverter, and used a separate cable with either one or three connectors on it. Arrays were constructed by linking together up to three D380s with a single drop cable, and then connecting them to other drop cables using larger twist-fit connectors.

In 2011 the entire lineup was replaced with the 3rd generation M215, combining the features of the M190 and D380 while improving reliability. Like the M190, the M215 was a single inverter, now in a much smaller box. Like the D380, the M215 used a trunk cabling system with short connector cables on the inverters. However, instead of one or three-drop cable, the M215’s Engage system, used a long roll of cables with connectors spliced into it. The installer cuts the Engage cable to the required length, and then caps the open ends that result.

In 2013 the M250 was released, offering a new grounding system (Integrated Ground – IG) that eliminates the otherwise NEC – required external grounding conductor, increased reliability, and increased efficiency (96.5%), along with a rating bump to 250W. Whereas previous models were all named after the maximum power rating, the M250 actually refers to its peak power. Using the same convention the M190 would be called the M199. The M250 is otherwise identical to the earlier M215 (which also was upgraded with IG) and compatible with the same Engage cabling system.

All Enphase models use power line communications to pass monitoring data between the inverters and the Envoy communications gateway. The Envoy stores daily performance data for up to a year, and, when available, allows Enphase’s Enlighten web service to download data approximately every 15 minutes. Customers and installers can review the data on the Enlighten web site.