Power Line Communications With A Line-Side Tap (Or Supply-Side, Or Plc) Installation; Multiple Envoys And Filtering; Using A Transformer To Isolate Communication Domains; This Is A Line-Side Tap (Or Supply-Side, Or Plc) Installation - enphase M250 Troubleshooting Manual

Troubleshooting an Enphase System

Power line communications with a Line-side Tap (or Supply-Side, or PLC) Installation

Note that line-side taps are called "parallel installations" in
Canada.
For information on line-side versus load-side connections,
refer to an informative series by John Wiles,
Making the Utility Connection: Perspectives on PV at
http://www.nmsu.edu/~tdi/pdf-resources/IAEI-9-10-05.pdf.
To facilitate power line communications with a line-side tap,
install the Envoy on an outlet off the PV subpanel where you
land the circuit breakers and prior to the utility tie-in. Plug in
the Envoy in near the electrical service center as this may
suffice.
In the case where the Envoy is on the premises wiring system,
try installing a pair of wireless Ethernet bridges to span the gap
between the Envoy and the router. A pair of power line
communication bridges comes with Envoy model ENV-120-01.
If this does resolve the issue, you may need to use a wireless
bridge. As the Envoy powered at the PV subpanel is not on the
premises' wiring system, add a wireless front end to the Envoy
using the wireless Ethernet bridge. This assumes the site is
set up for wireless access. The Linksys WRT610N is an example of a wireless bridge.

Multiple Envoys and Filtering

When installing multiple Envoys off of a single utility transformer also install filters to isolate each Envoy
into a separate communication domain, especially for large-scale projects. Use transformers or
aftermarket filters to isolate communication domains.
In a large-scale project, each sub-system (or communication domain) consists of modules, microinverters,
cables, branch circuit breakers, a microinverter subpanel, and a filter. A filter prevents power line
communication signals from one Envoy communication domain from interfering with Envoy
communication in another domain. The filter also offers the added benefit of eliminating electrical noise
from site loads.
With multiple communications domains, the total number of filters can be one less than the total number
of communication domains. If all other communications domains have filters, you can build one
communications domain without a filter (n – 1).
If your system contains fewer than 600 microinverters with a single Envoy on-site (a single
communications domain), you do not need a filter to isolate communications domains. A system of 600
microinverters has an AC inverter output rating of 129kW. For systems with fewer than 600
microinverters, the content in this section does not usually apply.

Using a Transformer to Isolate Communication Domains

Transformers provide excellent filtering between Enphase communication domains. A 480 V, 600 V, or
medium voltage interconnection requires a transformer to step the voltage down to 208/120 Wye. If the
project does not require transformers, or if a single, central transformer is selected, then you can filter
Envoy communication domains with commercially available power line filters.
 2014 Enphase Energy Inc.
25
August 2014