What is Power Line Communication and Why is 'Noise' a Problem?

Microinverter Power Line Communication (PLC)

Troubleshooting

This document provides guidance to overcome electrical noise when it causes power line communication issues.

What Is Power Line Communication and Why is 'Noise' a Problem?

Power line noise is interference caused by other devices using the same electrical wiring of a house or building. This interference inhibits Gateway communication with the microinverters. This results in inconsistent production display in Enlighten. Data is not lost; the Gateway is unable to collect data from the microinverters while communication is impaired.

The Enphase Gateway™ communicates with Enphase Microinverters over the AC electrical conductors using a 110kHz communication signal (144kHz in North America). This technology is known as Power Line Communication, or PLC. It is widely used in networking (Ethernet bridges or HomePlugs) and home automation applications (X10 for example).

Some common appliances produce electrical noise at similar frequencies. Noise produced may be continuous or intermittent at certain times of the day. If this noise occurs on the same electrical conductors as the PLC, it can disrupt communication between the Envoy and microinverters. In some cases, noise on the AC circuit can be so great that the Envov is unable to communicate adequately with the microinverters.

Examples of common equipment and appliances known to create noise and cause microinverter communication problems:

• Impulse noise: light switches, dimmer switches, irons, microwaves, touch lamps, and export limiting devices (or automatic controllers) using phase angle technology, such as the Solar Boost & Power Diverter.
• Unintended tonal noise: personal computers, battery chargers, mobile phone chargers, laptop chargers and power supplies, compact florescent lights with a failed ballast, uninterruptible power supplies (UPS), battery backup units, CD sockets, power strips, and surge protectors.
• Intended tonal noise: devices using power line communication such as Ethernet bridges, heavy rotating motors such as water pumps or refrigerators, workshop equipment such as drill-presses or wood routers, and many common kitchen appliances

Problems are often not observed when the microinverters are first installed. When the system owner later purchases a new computer or refrigerator, or when older appliances start to fail, noise may appear and the microinverters can fail to report. Follow the best practices described in this document during installation to avoid potential communication issues at the site.

Power line noise is interference caused by other devices using the same electrical wiring of a house or building. This interference inhibits Gateway communication with the microinverters. This results in inconsistent production display in Enlighten. Data is not lost; the Gateway is unable to collect data from the microinverters while communication is impaired.

Some common "noise makers" include:  power strips, GFI outlets, dimmer switches, appliances with heavy motors in them like refrigerators or washing machines, security systems, and bad circuit breakers.

For tips on reducing noise, refer to the Troubleshooting section in the Envoy Installation and Operation Manual.