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TECHNICAL BRIEF

M250 Microinverter System — Installation Planning

The M250 Microinverter

The Enphase M250™ Microinverter is a powerful and

efficient grid-tied microinverter. It is compatible with most

60-cell PV modules (to 300 Watts or higher) and installs

quickly and easily. It works with both three-phase 208

VAC and single-phase 240 VAC services. A separate

model is available for 230 VAC service in other regions.

For detailed installation information, refer to the

M250 Installation and Operations Manual or the M250

Quick Install Guide at http://www.enphase.com/support.

Microinverter Compatibility

The Enphase M250 is electrically compatible with all 60-cell modules. The PV module must also use PV

(photovoltaic) Wire. To ensure mechanical compatibility, be sure to order the correct module connector

type for both the M250 and PV module.

Model Number

Electrical Compatibility

Module Connector Type

M250-60-2LL-S22

M250-60-2LL-S22-NA

60 cell PV module

MC-4 Type 2 Locking or Amphenol H4

Locking

M250-60-2LL-S23

M250-60-2LL-S23-NA

60 cell PV module

Tyco Solarlock Locking*

NOTE: Tyco connectors on PV modules can vary in polarity, and either the male or

female connector may be positive. Only the MALE positive will mate with Enphase

Microinverters with S23 connectors. Be sure to order the correct connector type for both

microinverter and PV module from your distributor.

As a rule, the electrically-positive output of the PV module always connects to the positive input of the

microinverter. However, PV modules come with a variety of labels. For more information, refer to Mating

Microinverters with PV Modules for Correct Polarity at http://www.enphase.com/support.

Branch Circuit Capacity

Do not exceed the maximum number of microinverters in an AC branch circuit as listed in the following

table. You must protect each microinverter AC branch circuit with a 20A maximum breaker.

Maximum number of M250s per 20 amp AC Branch Circuit

Service type

Max M250s per AC branch

240V

208V

Summary of content (8 pages)

PAGE 1
TECHNICAL BRIEF M250 Microinverter System — Installation Planning The M250 Microinverter The Enphase M250™ Microinverter is a powerful and efficient grid-tied microinverter. It is compatible with most 60-cell PV modules (to 300 Watts or higher) and installs quickly and easily. It works with both three-phase 208 VAC and single-phase 240 VAC services. A separate model is available for 230 VAC service in other regions.
PAGE 2
M250 Installation Planning Installation Flow Every Enphase installation should include these basic steps. Plan to complete these steps in the order shown. 1. Register the System    First-time installers: go to https://enlighten.enphaseenergy.com/users/new and complete the form. Your login credentials will be emailed to you. ® Existing installers and those with new credentials: Log into the Enphase Enlighten software. Click “Add a New System” in the Installation Status widget. 2.
PAGE 3
M250 Installation Planning The Enphase Engage Cable The M250 has integrated DC and AC cables and connectors. The DC connectors attach to the PV module, while the AC connector attaches directly to the Engage Cable. No additional cabling is needed. The Engage Cable is a continuous length of 12 AWG, outdoor rated cable, with integrated connectors for microinverters. These connectors are preinstalled along the entire cable and spaced to accommodate either portrait and landscape PV module orientations.
PAGE 4
M250 Installation Planning Voltage Types and Conductor Count The Engage Cable is available for either 240VAC split phase or 208VAC three phase (Separate models are available for 230 VAC service). All cable connectors bear labels indicating their cable voltage designation. Typically used for residential applications, 240VAC cabling includes four conductors. Threephase 208VAC cabling includes five conductors and is used for most commercial installations.
PAGE 5
M250 Installation Planning Planning for Cable Lengths and Type The Engage Cable is flexible enough to adapt to almost any solar design. To determine the length and cable type that you need, take into account the following considerations:  Calculate the number of Enphase Microinverters to be installed on the AC branch. Be certain to allocate the correct number of connectors, including extra connectors for gaps and turns.
PAGE 6
M250 Installation Planning  Mixture of PV modules in both portrait and landscape installation. When PV modules are installed in mixed orientation (both portrait and landscape orientation), solutions include: 1. Engage Cable with 1.025 meter spacing between connectors results in cleanest install for the modules in portrait mode. For modules placed in landscape mode, plan for an unused connector between each PV module to achieve the required additional distance.
PAGE 7
M250 Installation Planning Microinverter Installation Requirements      Allow a minimum of 1.9 cm (0.75 inches) between the roof and the bottom of the microinverter. Allow 1.3 cm (0.50 inches) between the back of the PV module and the top of the microinverter. You must install the M250 under the module, out of rain and sun.
PAGE 8
M250 Installation Planning Enphase Items Required Quantity Description Order Number 120 M250 Microinverter M250-60-2LL-S22 or M250-60-2LL-S23 3 packs Cable clip (each pack contains 100 clips) ET-CLIP-100 1 pack Disconnect tool (each pack contains five tools) ET-DISC-05 1 pack Branch terminator (each pack contains 10 terminators) ET-TERM-10 Engage Cable divided into ten lengths: Each length should be about 20.4 meters (67 feet) with 12 connectors.