enphase C250 User manual

INSTALLATION AND OPERATION MANUAL
141-00025, Rev 03
Enphase C250 Microinverter
System

C250 System Installation and Operation
2015 Enphase Energy Inc. All rights reserved. 141-00025 Rev 03
2
Corporate Headquarters Contact Information
Enphase Energy Inc.
1420 N. McDowell Blvd.
Petaluma, CA 94954
USA
Company website: http://www.enphase.com
Enphase Energy customer support: enphase.com/en-us/support/contact
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant
to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with this
manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user will be required to correct
the interference at his own expense.
Other Information
Product information is subject to change without notice. All trademarks are recognized as the property of
their respective owners.
User documentation is updated frequently; Check the Enphase website
(http://www.enphase.com/support) for the latest information.
For warranty text refer to http://www.enphase.com/warranty.
For Enphase patent information refer to http://enphase.com/company/patents/.
© 2015 Enphase Energy Inc. All rights reserved.
Audience
This manual is intended for use by professional installation and maintenance personnel.

C250 System Installation and Operation
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Table of Contents
Important Safety Information .......................................................................................................................................... 5
Read this First.................................................................................................................................................. 5
Product Labels ................................................................................................................................................. 5
Safety and Advisory Symbols........................................................................................................................... 5
Safety Instructions............................................................................................................................................ 5
General Safety............................................................................................................................................. 5
Microinverter Safety..................................................................................................................................... 6
Engage Cable and Accessory Safety .......................................................................................................... 7
Envoy Safety................................................................................................................................................ 8
The Enphase C250 Microinverter System...................................................................................................................... 9
How the Microinverter Works......................................................................................................................... 10
System Monitoring ..................................................................................................................................... 10
Optimal Reliability ...................................................................................................................................... 10
Ease of Design........................................................................................................................................... 10
Planning for System Installation ................................................................................................................................... 11
Compatibility and Capacity............................................................................................................................. 11
Compatibility .............................................................................................................................................. 11
Branch Circuit Capacity ............................................................................................................................. 11
Utility Service Requirements...................................................................................................................... 11
Lightning and Surge Suppression.................................................................................................................. 12
Pre-installation Tasks..................................................................................................................................... 12
Required System Components ...................................................................................................................... 13
Other Items................................................................................................................................................ 13
Enphase System Installation and Commissioning........................................................................................................ 14
Step 1: Register the System........................................................................................................................... 15
Step 2: Place the Envoy................................................................................................................................. 15
Step 3: Position the Enphase Engage Cable................................................................................................. 16
Step 4: Terminate the Unused End of the Engage Cable.............................................................................. 17
Step 5: Attach the Microinverters to the PV Racking ..................................................................................... 18
Step 6: Dress the Engage Cable.................................................................................................................... 19
Step 7: Connect the Microinverters................................................................................................................ 20
Step 8: Connect to an AC Branch Circuit Junction Box ................................................................................. 21
Step 9: Complete the Installation Map ........................................................................................................... 23
Step 10: Connect the PV Modules................................................................................................................. 24
Step 11. Energize the System........................................................................................................................ 24
Step 12: Connect the Envoy to the Internet ................................................................................................... 25
Method A: Ethernet Cable.......................................................................................................................... 25
Method B: Wi-Fi (Enphase Wireless Adapter)........................................................................................... 25
Verification: Check the Internet Connection............................................................................................... 25
Step 13: Use the Envoy to Complete System Setup...................................................................................... 26
Step 14: Build the Virtual Array...................................................................................................................... 26
Troubleshooting............................................................................................................................................................ 27
Status LED Indications and Error Reporting .................................................................................................. 27
Startup LED Operation............................................................................................................................... 27
Post-Startup LED Indications..................................................................................................................... 27
DC Resistance Low –Power Off Fault ...................................................................................................... 28
Other Faults ............................................................................................................................................... 28
Troubleshoot an Inoperable Microinverter...................................................................................................... 28
Disconnect a Microinverter............................................................................................................................. 30
Install a Replacement Microinverter............................................................................................................... 31
Engage Cable Planning and Ordering.......................................................................................................................... 32
Connector Spacing Options ........................................................................................................................... 32
Cabling Ordering Options............................................................................................................................... 33
Planning for Cable Lengths and Type............................................................................................................ 33

C250 System Installation and Operation
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Technical Data.............................................................................................................................................................. 35
Technical Considerations............................................................................................................................... 35
Specifications................................................................................................................................................. 35
C250-72-2LN-S2 Microinverter Specifications........................................................................................... 35
Engage Cable Specifications..................................................................................................................... 37
Enphase Installation Map............................................................................................................................... 38
Sample System Diagram................................................................................................................................ 39

C250 System Installation and Operation
2015 Enphase Energy Inc. All rights reserved. 141-00025 Rev 03
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Important Safety Information
Read this First
This manual and describes how to safely install and operate the Enphase® C250 Microinverter™,
the Enphase® Envoy-C Communications Gateway™, and the Enphase® C250 Engage Cable™ for utility
interactive applications. Read and comply with the following safety instructions.
Product Labels
The following symbols appear on the product label and are described here:
WARNING: Hot surface.
DANGER: Refer to safety instructions.
DANGER: Risk of electrical shock.
Safety and Advisory Symbols
To reduce the risk of electric shock, and to ensure the safe installation and operation of the Enphase® Microinverter,
the following safety symbols appear throughout this document to indicate dangerous conditions and important safety
instructions.
DANGER! This indicates a hazardous situation, which if not avoided, will result in death or serious
injury.
WARNING! This indicates a situation where failure to follow instructions may be a safety hazard or
cause equipment malfunction. Use extreme caution and follow instructions carefully.
WARNING! This indicates a situation where failure to follow instructions may result in burn injury.
NOTE: This indicates information particularly important for optimal system operation. Follow
instructions closely.
Safety Instructions
General Safety
CAUTION: Before installing or using the Enphase Microinverter, read all instructions and
cautionary markings in the technical description, on the Enphase Microinverter System, and on the
photovoltaic (PV) equipment.
DANGER: Risk of electric shock. Do not use Enphase equipment in a manner not specified by the
manufacturer. Doing so may cause death or injury to persons, or damage to equipment.
DANGER: Risk of electric shock. Be aware that installation of this equipment includes risk of
electric shock. Do not install the AC junction box without first removing AC power from the Enphase
System.
DANGER: Risk of electric shock. The DC conductors of this photovoltaic system are ungrounded
and may be energized.
WARNING: Risk of electric shock. Always de-energize the AC branch circuit before servicing.
Never disconnect the DC connectors under load.
WARNING: Risk of electric shock. Risk of fire. Only use electrical system components approved for
wet locations.

C250 System Installation and Operation
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WARNING: Risk of electric shock. Risk of fire. Only qualified personnel should troubleshoot, install,
or replace Enphase Microinverters or the EngageCable and Accessories.
WARNING: Risk of electric shock. Risk of fire. Ensure that all AC and DC wiring is correct and that
none of the AC or DC wires are pinched or damaged. Ensure that all AC junction boxes are
properly closed.
WARNING: Risk of electric shock. Risk of fire. Do not exceed the maximum number of
microinverters in an AC branch circuit as listed in the manual. You must protect each microinverter
AC branch circuit with a 20A maximum breaker.
WARNING: Do not connect Enphase Microinverters to the grid or energize the AC circuit(s) until
you have completed all of the installation procedures and have received prior approval from the
electrical utility company.
NOTE: To ensure optimal reliability and to meet warranty requirements, the Enphase Microinverter
System must be installed according to the instructions in this manual.
NOTE: The AC and DC connectors on the cabling are rated as a disconnect only when used with
an Enphase Microinverter.
NOTE: Protection against lightning and resulting voltage surge must be in accordance with local
standards.
NOTE: Many PV modules have a central stiffening brace. In these cases, do not position the
connector and microinverter at the exact center of the PV module. Instead, position the drop
connectors so that the connectors do not conflict with the braces.
NOTE: Completely install all microinverters and all system AC connections prior to installing the PV
modules.
Microinverter Safety
WARNING: Risk of Skin Burn. The body of the Enphase Microinverter is the heat sink. Under
normal operating conditions, the temperature is 15°C above ambient, but under extreme conditions
the microinverter can reach a temperature of 80°C. To reduce risk of burns, use caution when
working with microinverters.
WARNING: Risk of electric shock. Risk of fire. If the AC cable on the microinverter is damaged, do
not install the unit.
WARNING: Risk of electric shock. Risk of fire. Do not attempt to repair the Enphase Microinverter;
it contains no user-serviceable parts. If it fails, contact Enphase customer service to obtain an RMA
(return merchandise authorization) number and start the replacement process. Tampering with or
opening the Enphase Microinverter will void the warranty.
WARNING: Risk of Fire. When pairing with C250, the PV module DC conductors must be labeled
“PV Wire” or “PV Cable”.
WARNING: Risk of Equipment Damage. You must match the DC operating voltage range of the PV
module with the allowable input voltage range of the Enphase Microinverter.
WARNING: Risk of Equipment Damage. The maximum open circuit voltage of the PV module must
not exceed the specified maximum input DC voltage of the Enphase Microinverter.
WARNING: Risk of Equipment Damage. The microinverter must be installed under the module, out
of rain and sun. Do not mount the microinverter in a position that allows long-term exposure to
direct sunlight or in a vertical orientation that allows water to collect in the DC connector recess. Do
not install the microinverter black side up or vertically, with the DC connectors facing up.
WARNING: Be aware that only qualified personnel may connect the Enphase Microinverter to the
utility grid.
NOTE: Enphase Microinverters have field-adjustable voltage and frequency trip points that may
need to be set, depending upon local requirements. Only an authorized installer with the
permission and following requirements of the local electrical authorities should make adjustments.

C250 System Installation and Operation
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Engage Cable and Accessory Safety
DANGER: Risk of electric shock. The Engage Cable terminator cap must not be installed while
power is connected.
WARNING: Risk of electric shock. Risk of fire. When stripping the sheath from the Engage Cable,
make sure the conductors are not damaged. If the exposed wires are damaged, the system may
not function properly.
WARNING: Risk of electric shock. Treat all connector contacts as though they are live. Pin one in
the splice box (drop connector) is live, though not used.
WARNING: Risk of electric shock. Risk of fire. Do not leave AC connectors on the Engage Cable
uncovered for an extended period. If you do not replace the microinverter immediately, you must
cover any unused connector with a sealing cap. Sealing caps may not be reused.
WARNING: Risk of electric shock. Risk of fire. Make sure protective sealing caps have been
installed on all unused AC connectors. Unused AC connectors are live when the system is
energized by the grid. Sealing caps may not be reused.
WARNING: Use the terminator only once. If you open the terminator following installation, the
latching mechanism is destroyed. Do not reuse the terminator. Do not circumvent or manipulate the
latching mechanism.
CAUTION: When installing the Engage Cable, secure any loose cable to minimize tripping hazard.
NOTE: Check the labeling on the Engage Cable drop connectors to be sure that the cable matches
the electrical utility service at the site.
NOTE: There are two release-holes in the drop connector on the cable. These are not for mounting
but are used to disconnect the connector. Keep these release holes clear and accessible.
NOTE: When looping the Engage Cable, do not form loops smaller than 4.75 in. (12 cm) in
diameter.
NOTE: If you need to remove a sealing cap, you must use the Enphase disconnect tool or a
screwdriver. Sealing caps may not be reused.
NOTE: When installing the Engage Cable and accessories, adhere to the following:
•Do not expose the terminator cap or cable connections to directed, pressurized liquid (water
jets, etc.).
•Do not expose the terminator cap or cable connections to continuous immersion.
•Do not expose the terminator cap or cable connections to continuous tension (e.g., tension
due to pulling or bending the cable near the connection).
•Use only the connectors and cables provided.
•Do not allow contamination or debris in the connectors.
•Use the terminator cap and cable connections only when all parts are present and intact.
•Do not install or use in potentially explosive environments.
•Do not allow the terminator to come into contact with open flame.
•Make sure that all terminator cap seals are seated correctly in the wire organizer.
•Fit the terminator cap using only the prescribed tools and in the prescribed manner.
•Use the terminator to seal the conductor end of the Engage Cable; no other method is
allowed.
NOTE: Do not use the shipping cap to cover unused connectors. The shipping cap does not
provide an adequate environmental seal. Enphase sealing caps are required to protect against
moisture ingress.

C250 System Installation and Operation
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Envoy Safety
WARNING: Risk of electric shock. Do not attempt to repair the Enphase Envoy Communications
Gateway; it contains no user-serviceable parts. If it fails, contact Enphase customer service to
obtain an RMA (return merchandise authorization) number and start the replacement process.
Tampering with or opening the Enphase Envoy will void the warranty.
WARNING: Risk of equipment damage. Do not remove power from the Envoy if the LCD screen
displays: “Upgrading. . . Do Not Unplug.”
NOTE: DO NOT route the power cable or the Ethernet cable through the cable tray.
NOTE: Do not plug the Envoy into a power strip, surge protector, or uninterruptable power supply
(UPS). These devices impede power line communications.

C250 System Installation and Operation
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The Enphase C250 Microinverter System
Used with a transformer, the C250 Microinverter System meets the needs of large commercial
installations where power distribution is 480Y/277V or medium voltage (MV).
With the fourth generation Enphase Microinverters, the DC circuit within the microinverter is isolated and
insulated from ground. Ground fault protection (GFP) is integrated into the microinverter. Because of this,
the microinverters do not require a GEC. As a result, it takes less time to install than other microinverters,
saves money, and increases safety. Fourth generation microinverters include the C250.
This integrated system maximizes energy harvest, increases system reliability, and simplifies design,
installation and management.

C250 System Installation and Operation
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How the Microinverter Works
The Enphase Microinverter maximizes energy production from your photovoltaic (PV) array. Each
Enphase Microinverter is individually connected to one PV module in your array. This unique
configuration means that an individual Maximum Peak Power Point Tracker (MPPT) controls each PV
module. This ensures that the maximum power available from each PV module is exported to the utility
grid regardless of the performance of the other PV modules in the array. That is, although individual PV
modules in the array may be affected by shading, soiling, orientation, or PV module mismatch, the
Enphase Microinverter ensures top performance for its associated PV module. The result is maximum
energy production from your PV system.
System Monitoring
Once you install the Envoy Communications Gateway and provide an Ethernet connection to your
broadband router or modem, the Enphase Microinverters automatically begin reporting to the Enphase
Enlighten web server. The Enlighten software presents current and historical system performance trends,
and it informs you of PV system status.
Optimal Reliability
Microinverter systems are inherently more reliable than traditional inverters. The distributed nature of a
microinverter system ensures that there is no single point of system failure in the PV system. Enphase
Microinverters are designed to operate at full power at ambient temperatures as high as 65C (150F).
The microinverter housing is designed for outdoor installation and complies with the NEMA 6
environmental enclosure rating standard:
NEMA 6 rating definition: Indoor or outdoor use primarily to provide a degree of
protection against hose-directed water, the entry of water during occasional temporary
submersion at a limited depth, and damage from external ice formation.
NOTE: To ensure optimal reliability and to meet warranty requirements, the Enphase
Microinverter must be installed according to the instructions in this manual.
Ease of Design
PV systems using Enphase Microinverters are very simple to design and install. You will not need string
calculations, and you can install individual PV modules in any combination of PV module quantity, type,
age and orientation. You won’t need to install cumbersome traditional inverters. Each microinverter
quickly mounts on the PV racking, directly beneath each PV module. Low voltage DC wires connect from
the PV module directly to the co-located microinverter, eliminating the risk of personnel exposure to
dangerously high DC voltage.

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Planning for System Installation
The Enphase Microinverter is compatible with most 60- and 72-cell PV modules and installs quickly and
easily. It ships with 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 for C250 is available in three connector spacing options to meet varying site
requirements. For Engage Cable ordering information, see “Engage Cable Planning and Ordering” on
page 32.
Compatibility and Capacity
Refer to the Enphase Compatibility Calculator at:
http://enphase.com/module-compatibility-calculator-m250-update/ to ensure PV module electrical
compatibility. To ensure mechanical compatibility, be sure to order the correct connector type for both
microinverter and PV module from your distributor.
WARNING: Risk of fire. When connecting to a C250 Microinverter, the PV module DC
conductors must be labeled "PV Wire" or "PV Cable” to be compliant with NEC 690.35(D)
for Ungrounded PV Power Systems.
Compatibility
Model Number
Works with PV Module Type
PV Module Connector Type
C250-72-2LN-S2
60-cell or 72-cell, to 350 W
MC-4 locking connector
C250-72-2LN-S5
60-cell or 72-cell, to 350 W
Amphenol connector
Branch Circuit Capacity
Plan your AC branch circuits to meet the following limits for maximum number of Enphase Microinverters
per branch when protected with a 20-amp over-current protection device (OCPD).
Maximum C250s
per phase
Maximum C250s
per AC branch circuit
16
48
Utility Service Requirements
When used with a transformer, the Enphase C250 Microinverter works with three-phase 480Y/277V
service. Install an auto-transformer or isolation transformer so that the voltage presented to the
microinverter is limited to no more than 248V, line to neutral.

C250 System Installation and Operation
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Lightning and Surge Suppression
Enphase Microinverters have integral surge protection, greater than most traditional inverters. However, if
the surge has sufficient energy, the protection built into the microinverter can be exceeded, and the
equipment can be damaged. For this reason, Enphase recommends that you protect your system with
lightning and/or surge suppression devices. In addition to having some level of surge suppression, it is
also important to have insurance that protects against lightning and electrical surges.
NOTE: Protection against lightning and resulting voltage surge must be in accordance
with local standards.
Pre-installation Tasks
Install supporting structures, home-run wiring, load centers, revenue grade meter, and any other
equipment required for your installation. Install this equipment per manufacturer instructions.
•Verify DC polarity between the PV module and the microinverter by temporarily connecting a
PV module to a microinverter with no grid connection. The microinverter LED lights solid
green for a few seconds to indicate compatibility. After two minutes the LED will flash red to
indicate that no grid is present. This is normal.
•Install an auto-transformer or isolation transformer so that the voltage presented to the
microinverter is limited to no more than 248V, line to neutral.
•Auto-transformer: An auto-transformer is more affordable, smaller, lighter and more
efficient than an isolation transformer. You can use one to generate the operating voltage
for C250 from a 480Y/277V grid. The primary disadvantages of auto-transformers are
that they do not provide isolation and do not derive a neutral from a delta configured
system. Used in boost mode (as viewed from the PV side), these transformers usually
have taps for adjustments to the PV side voltage.
•Isolation Transformer: Isolation transformers with a WYE configured winding on the PV
side can derive a neutral conductor when the grid side is delta configured, filter electrical
noise and communication signals, and provide isolation of communication domains.
These transformers usually have taps for adjustments to the PV side voltage.
•Install a phase coupler to couple the Enphase power line communication signal between the
three phases. You need a phase coupler with each Envoy-C in a C250 system to allow
communication with the microinverters on all three phases.
•Install Enphase Line Filters (model LCF-250-PC), if needed. If you have more than one
communication domain and multiple Envoy-Cs that are tied to a common service panel or off
of a single transformer, you need filters to prevent cross-talk between the communication
domains. You can accomplish this with power line filters or with a single isolation transformer
feeding a single communication domain, such as when a medium voltage transformer is
provided for each sub-array. You must also physically separate the racking, conduits and
wires of one communication domain from another communication domain by at least 12
inches.
•Install surge protection. An inline surge protective device provides the greatest level of
protection, but is usually more expensive than a surge protective device that sits in parallel to
the microinverter panel board. If using an inline surge protective device, locate the Envoy-C
and C250s together on the load side of this device.
Refer to the C250 Commercial Design Guide at http://www.enphase.com/support for details on tested
transformers and other devices.

C250 System Installation and Operation
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Required System Components
You need the following components to install the C250 system:
•Enphase C250 Microinverter: (model C250-72-2LN-S2 or C250-72-2LN-S5)
•Enphase Envoy-C Communications Gateway: (model ENV-C250). The Envoy has a 250V-
rated, NEMA 6-15P plug. The receptacle must be NEMA 6-15R.
NOTE: The C250 Microinverter works only with the Envoy-C (model ENV-C250).
•Enphase Engage Cable:
Model number
PV module orientation
ET10-277-BULK
Portrait, 60- and 72-cell modules
ET17-277-BULK
Landscape, 60-cell modules
ET21-277-192-12AWG
Landscape, 72-cell modules
For more information, see “Engage Cable Planning and Ordering” on page 32.
•Transformer: The transformer must adapt the utility voltage (usually 480Y/277V) to no more
than 248V line-to-neutral for connection to the Envoy-C and C250 Microinverters.
•Surge protection device(s).
•Phase Coupler
•Enphase Line Filters (model LCF-250-PC), for additional Envoys, if needed.
Other Items
•Cable clips (model ET-CLIP-100)
•Sealing caps, as needed (model ET-SEAL-10). One needed for each unused drop on the
Engage Cable.
•Terminators, as needed (model ET-TERM-10). One needed at the end of each AC branch
circuit.
•Enphase disconnect tool (model ET-DISC-05). You can substitute numbers 2 and 3 Phillips
screwdrivers.
•Engage Couplers (splice kits), as needed. (ET-SPLK-05)
•Commercial grade NEMA 6-15R receptacle required for each Envoy
•Outdoor-rated, weather-proof AC junction box(es)
•Gland or strain relief fitting (one per AC junction box)
•Number 2 and 3 Phillips screwdrivers
•Torque wrench, sockets, wrenches for mounting hardware
•Adjustable wrench or open-ended wrench (for terminators)
•Handheld mirror (to view LEDs on the undersides of the microinverters)
•Laptop or mobile device for Envoy set up (recommended)
•Bluetooth scanner for use with Enphase Installer Toolkit

C250 System Installation and Operation
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Enphase System Installation and Commissioning
Installing the Enphase Microinverter System involves several key steps. Each step listed here is detailed
in the following pages. Follow the instructions in this section to install Enphase Microinverters.
Step 1: Register the System
Step 2: Place the Envoy® Communications Gateway™
Step 3: Position the Enphase Engage™Cable
Step 4: Terminate the Unused End of the Engage Cable
Step 5: Attach the Microinverters to the PV Racking
Step 6: Dress the Enphase Engage Cable
Step 7: Connect the Microinverters
Step 8: Connect to an AC Branch Circuit Junction Box
Step 9: Complete the Installation Map
Step 10: Connect the PV Modules
Step 11: Energize the System
Step 12: Connect the Envoy to the Internet
Step 13: Use the Envoy to Complete System Setup
Step 14: Build the Virtual Array
WARNING: Risk of electric shock. Risk of fire. Always de-energize the AC branch circuit
before servicing. Never disconnect the DC connectors under load.
WARNING: DO NOT connect Enphase Microinverters to the utility grid or energize the
AC circuit(s) until you have completed all of the installation procedures as described in
the following sections.

C250 System Installation and Operation
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Step 1: Register the System
Register the Envoy at the beginning of the PV installation.
a. Use your previously issued username and password to log in to in Enlighten.
If you haven’t registered, go to www.enphase.com and click Enlighten Login.
b. At the installer dashboard, click Add a New System.
If you have already registered the site, find the system under Installations in Progress.
c. Under System, enter the system
Name, Type and Installer
Reference (optional).
d. Enter Installer information.
e. Under Owner, enter the Name,
Email, and Phone.
f. Under Location, enter the Country
and address information.
NOTE: If you select a country
other than the US, or if you
select Hawaii as the state
under Location, the Grid
Profile menu appears. For
most regions, you do not need
to select a grid profile when
installing the C250 because it
is preset with the appropriate
profile.
However, when inter-
connecting to grids managed
by Hawaii Electric Industries
(HEI), including HECO, you
must refer to the C250
Commercial Design Guide,
Appendix A: Hawaiian
Electric Industries
Requirements for C250
Projects for specific
instructions on setting this
profile and for other
requirements specific to your
installation.
g. Under Envoy, select the Internet Connection type and enter the Envoy Serial Number.
h. Under Modules, enter total number of modules, type, etc.
i. Click Save to submit the form. You will receive a confirmation message: “Activation Created
Successfully.”
Step 2: Place the Envoy
The Envoy’s power line communication signal must be “coupled” between the three phases to allow the
Envoy to communicate with all of the microinverters in the system.
a. Install a phase coupler, or wire a capacitor into the system. With either solution, install the device on
the load side of the over-current protection device.

C250 System Installation and Operation
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b. Plug the AC cord into a dedicated NEMA 6-15R receptacle. This receptacle must be indoors or in an
environmentally protected location. Locate the Envoy with the phase coupler and line filter as shown
in the System Diagram on page 39.
Step 3: Position the Enphase Engage Cable
The Engage Cable is a continuous length of outdoor-rated cable with integrated connectors for
microinverters. These connectors are preinstalled along the Engage Cable at intervals to accommodate
horizontal or vertical PV module widths. The microinverters plug directly into the connectors, and the
Engage Cable is terminated into the junction box that feeds electricity back to the system AC disconnect.
For more information, see “Engage Cable Planning and Ordering” on page 32.
NOTE: Make sure you are using the correct cable type. Use three-phase cable (model
numbers ET10-277-BULK, ET17-277-BULK, or ET21-277-192-12AWG). See “Engage
Cable Planning and Ordering” on page 32. Check the labeling on the drop connectors to
verify the voltage type (277).
a. Plan the cable route so that the drop connectors on the Engage Cable align with each PV
module. Allow extra length for slack, cable turns and any obstructions.
b. Measure the path of the AC branch circuit and cut a length of Engage Cable to meet your
needs.
c. Lay the Engage Cable along the installed racking for the AC branch circuit. Position the
connectors so that they align with the PV modules. Allow extra length for slack, cable turns
and any obstructions.
WARNING: Risk of fire. Plan the AC branches so that they do not exceed the maximum
number of microinverters in an AC branch circuit as listed on page 11 of this manual. You
must protect each microinverter AC branch circuit with a 20 A maximum breaker.
NOTE: Many PV modules have a central stiffening brace. In these cases, do not position
the connector and microinverter at the exact center of the PV module. Instead, position
the drop connectors so that the connectors do not conflict with the braces.
d. PV module widths vary by manufacturer. On the Engage Cable, connectors are spaced at
intervals to allow for the widest PV modules compatible with Enphase Microinverters. If
narrower PV modules are used, it may be necessary to account for excess cable by looping
the cable at suitable intervals.
NOTE: When looping the Engage Cable, do not form loops smaller than 4.75 inches
(12 cm) in diameter.

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Step 4: Terminate the Unused End of the Engage Cable
WARNING: Risk of Electrical Shock. Do not install the terminator cap while power is
connected.
Terminate the far end of the Engage Cable as follows.
a. Remove 60 mm (2.5 inches) of the cable
sheath from the conductors.
b. Check that all terminator parts are
present.
c. Slide the hex nut onto the Engage Cable.
d. Insert the Engage Cable all the way into
the wire organizer (up to the stop).
e. Bend the individual wires back into the recesses in the wire organizer so that they angle back
toward the cable.
f. Cut the individual wires so that no excess extends outside of
the wire organizer. The portions that angle back will need to
extend enough to fit neatly into the 0.5 cm (0.2 in) recesses in
the wire organizer and flush with the edge of the cap.
g. Place cap over the wire organizer.
h. Hold the cap stationary with an Enphase disconnect tool, or
insert a #2 Phillips screwdriver.
i. Use a 22 mm (7/8 inch) wrench to tighten the
hex nut until the latching mechanism is screwed
all the way to the base. Never unscrew the hex
nut. This action can twist and damage the
cable.
j. Use a tie wrap or cable clip to attach the cable to
the PV racking, so that the Engage Cable and
terminator do not touch the roof.
k. Ensure that all cabling is located underneath the
PV module.
hex nut
wire organizer
cap

C250 System Installation and Operation
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18
Step 5: Attach the Microinverters to the PV Racking
a. Mark the approximate centers of each PV module on the PV racking.
b. Evaluate the location of the microinverter with respect to the PV module DC junction box or
any other obstructions.
c. Ensure that the microinverter does not interfere with the PV module frame or stiffening
braces.
d. Ensure that the connector from the microinverter can easily reach the connector on the
Engage Cable.
e. Allow a minimum of 1.9 cm (0.75 inches) between the roof and the bottom of the
microinverter. Also allow 1.3 cm (0.50 inches) between the back of the PV module and the
top of the microinverter.
WARNING: Risk of equipment damage. You must install the microinverter under the
module, out of rain and sun. Do not mount the microinverter in a position that allows long-
term exposure to direct sunlight or in a vertical orientation that allows water to collect in
the DC connector recess. Do not install the microinverter black-side up or vertically, with
the DC connectors facing up.
f. Mount one microinverter at each location
using suitable hardware. The indicator
light on the underside of the
microinverter will be facing the roof.
NOTE: Do not install the
microinverter black side up or
vertically, with the DC connectors
facing up.
g. Torque the microinverter fasteners to the
values shown. Do not over torque.
•6 mm (1/4”) mounting hardware: 5 N m (45 to 50 in-lbs)
•8 mm (5/16”) mounting hardware: 9 N m (80 to 85 in-lbs)
NOTE: Using a power screwdriver to tighten the mounting hardware is not recommended
due to the risk of thread galling.

C250 System Installation and Operation
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Step 6: Dress the Engage Cable
NOTE: Adhere to the following requirements:
•Do not expose the cable connections to directed, pressurized liquid (water jets, etc.).
•Do not expose the cable connections to continuous immersion.
•Do not expose the AC connector to continuous tension (e.g., tension due to pulling or
bending the cable near the connection)
•Use only the connectors and cables provided.
•Do not allow contamination or debris in the connectors.
•Use the cable and connectors only when all parts are present and intact.
a. Attach the Engage Cable to the PV racking using the
cable clips, or you may use tie wraps. The cable clips
are designed so that the cable from the microinverter
can also be dressed into the clip underneath the
Engage Cable.
NOTE: There are two release-holes in the drop
connector on the cable. These are not for mounting
but are used to disconnect the connector. Keep
these release holes clear and accessible.
b. Dress the Engage Cable so that it does not contact the
roof.
There are several ways to support the cable. One
method is to place tie wraps or clips on either side of the
connector. Use one or two additional clips, tie wraps, or
other support scheme to secure the cable between
connectors.
NOTE: When looping the Engage Cable, do not
form loops smaller than 4.75 inches (12 cm) in diameter.
WARNING: Tripping Hazard. Loose cables can become a tripping hazard. Dress the
Engage Cable to minimize tripping potential.
release holes

C250 System Installation and Operation
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Step 7: Connect the Microinverters
a. Remove and discard the temporary shipping caps from
the Engage Cable and connect the microinverter. There
are two latching mechanisms within the connectors.
Listen for two clicks as the connectors engage. Ensure
that both latching mechanisms have engaged.
b. Repeat for all microinverters in the AC branch circuit.
c. Cover any unused connector with a sealing cap. Listen
for two clicks as the connectors engage. Ensure that
both latching mechanisms have engaged.
NOTES: Do not use the temporary shipping
cap to cover unused connectors. The
shipping cap does not provide an adequate
environmental seal. Enphase sealing caps are
required to protect against moisture ingress.
Enphase sealing caps are IP67 rated. Within
the term “IP67”, “IP” indicates an Ingress
Protection (IP) rating against dust and liquids.
This specific rating of IP67 indicates that this connector protects against all dust particles
and immersion in liquid.
WARNING: Risk of electric shock. Risk of fire. Make sure protective sealing caps have
been installed on all unused AC connectors. Unused AC connectors are live when the
system is energized by the utility system. Sealing caps may not be reused.
NOTE: If you need to remove a sealing cap, you must use the Enphase disconnect tool
or a #3 Phillips screwdriver. See “Disconnect a Microinverter” on page 30. Sealing caps
may not be reused.
d. Avoid skipping Engage Cable connectors by using an Engage Coupler to connect two
Engage Cables or to connect Engage Cable to field cable.
NOTE: When cable connectors are left unused on a three-phase system, it creates a
phase imbalance on the branch circuit. If multiple cable connectors are skipped over
multiple branch circuits, the imbalance can multiply