Component Guide
Planning an Ensemble Technology System – North America
21 © 2020 Enphase Energy Inc. All rights reserved. December 8, 2020
Current Transformers (CTs)
It is critical that installers correctly configure the Envoy, with the combined solar PV output passing through the
production CT. The production CT monitors only the PV output circuit(s) and must not have Encharge battery
circuit(s) installed on it. Install the Encharge battery circuit(s) on the load side of the production CTs on the correct
terminals in Enpower smart switch.
Installers may extend the consumption CT leads, but not the production CT leads. Therefore, it is best to locate the
Envoy close to the microinverter output circuits and then extend consumption CT wires if necessary. Refer to the IQ
Envoy Installation and Operations Manual or the Enphase Envoy-S Installation and Operation Manual when installing
and/or extending consumption CTs. Refer also to the Tech Brief: Four Guidelines for Successful Current Transformer
(CT) Installation.
Enpower Smart Switch Connections
The Enpower smart switch can accept a maximum of 64 A of continuous output current (maximum 80A breaker) of a
combined PV subpanel or IQ Combiner (labeled AC Combiner). The busbar in the Enpower smart switch can accept
a maximum of an 80 A breaker for the IQ Combiner over current protection.
The Enpower smart switch can accept a maximum of 64 A of rated output current (maximum 80A breaker) of
combined Encharge storage system circuits. The busbar in the Enpower smart switch can accept a maximum of an
80 A breaker for the Encharge storage system circuit over current protection. This equates to a maximum of twelve
Encharge 3 storage units or four Encharge 10 units per Enpower. Up to six Encharge 3 storage units or two
Encharge 10 units, equal to 32 A of rated output current, can be connected in series prior to landing on the Encharge
terminal in the Enpower smart switch and protected by a no higher than a 40 A over current protection breaker. If
more than six Encharge 3 storage systems (or more than two Encharge 10 storage systems) are to be connected to
Enpower smart switch, an external subpanel must be used to combine each circuit of up to 32 A of rated output
current Encharge storage system circuits. You should size conductors appropriately for the overcurrent protection
selected for the application.
Voltage Regulation Considerations
When the Encharge storage system is charging, it acts like a load, and the voltage decreases at the terminals of the
battery based upon Ohm’s law and wire resistance. When the Encharge storage system is discharging to feed loads,
it behaves like a source, and the voltage increases at the terminals of the battery.
The voltage rise to voltage drop delta divided by the nominal voltage is roughly equivalent to voltage regulation. Since
the peak charge and discharge values for Encharge are the same value, voltage rise and voltage drop will be the
same value.
Voltage regulation in Ensemble is calculated as
where:
is the voltage change from 0 to max current out of Encharge, and
is the nominal RMS voltage.
Ensure that the Encharge storage system conductors are sized correctly for the number of units on the circuit and
voltage regulation does not exceed 1% between the first Encharge storage system and Enpower smart switch.
Rapid Shutdown Considerations
2017 NEC 690.12 requires a rapid shutdown for PV Systems on buildings by an initiation device in a readily
accessible location. In grid interactive systems this is often the service disconnecting means or PV system
disconnect. Rapid shutdown requirements do not apply to optional standby systems such as energy storage and as
seen in Figure 1, the PV system disconnect can still initiate rapid shutdown.
The rapid shutdown initiation device can be either:
- the PV system breaker in Enpower,
- an additional disconnect such as a fusible disconnect between Enpower and the IQ Combiner, or
- the circuit breakers in the IQ Combiner since these breakers are less than six and grouped.
The rapid shutdown initiator must be labeled in accordance with 2017 NEC 690.56.
Enphase IQ 6 / 7 series and M215 and M250 microinverters comply with the rapid shutdown requirements per the UL
certifications.