Understanding CAN & RS485 Protocols in Inverter Communication

The Backbone of Reliable Solar + Storage System Integration


When integrating energy storage with solar inverters, the importance of communication protocols is often underestimated. Two of the most widely used protocols in the solar + ESS ecosystem are CAN (Controller Area Network) and RS485. These low-level communication systems enable batteries, inverters, and monitoring devices to talk to each other — and choosing the right one (or understanding both) is essential for reliable operation, seamless integration, and remote monitoring.

This article will walk you through:

  • The basic differences between CAN and RS485
  • When each protocol is used in inverter-battery systems
  • Compatibility and integration tips for installers and exporters

1. What Is RS485?

RS485 is a serial communication standard used in many industrial and building automation systems. It allows multiple devices to share a two-wire differential signal line, with simple data transmission at relatively low speeds over long distances (up to 1200 meters).

Key Features:

  • Multi-drop support (up to 32 devices on one bus)
  • Simple wiring (twisted pair)
  • Common in inverter-to-BMS and inverter-to-monitor connections
  • Open and flexible, but lacks error-handling robustness

2. What Is CAN?

CAN Bus was originally developed for automotive systems and is now widely used in energy storage. It’s a more robust protocol designed for real-time communication between microcontrollers, with advanced error handling and prioritization.

Key Features:

  • Fast and reliable (up to 1 Mbps, low latency)
  • High noise immunity
  • Used in most lithium battery BMS systems today
  • Supports complex messaging, e.g. detailed battery telemetry, alarms

3. Where Are These Protocols Used in ESS?

Device ConnectionCommon Protocol
Inverter ↔ Battery BMSCAN or RS485 (depends on brands)
Inverter ↔ MeterRS485 (Modbus RTU)
Inverter ↔ EMS ControllerRS485 or Ethernet
Battery Module ↔ BMSCAN

Note: Many lithium battery brands (especially LFP types) now rely on CAN as default, especially for high-voltage stacks or rack systems.


4. CAN vs RS485: Which One to Use?

FeatureRS485CAN
SpeedUp to 115 kbpsUp to 1 Mbps
DistanceUp to 1200mUp to 40m (typical)
Device Count32 devices (with repeaters)Usually up to 16 nodes
Error HandlingBasicAdvanced
Use CaseMeters, inverters, EMSBattery BMS, EVs, real-time data

5. Tips for Installers and Traders

  • Always check protocol compatibility when mixing brands (e.g., BYD battery with Growatt inverter may use CAN with specific firmware).
  • Don’t mix RS485 and CAN lines — they require different connectors and protocols.
  • Use shielded twisted pair cables for both protocols to reduce noise.
  • Some inverters (like Deye, Luxpower, Victron) support both RS485 and CAN, but configuration must be set manually.
  • If your system isn’t working, check baud rate, device address (for RS485), and CAN termination resistors.

6. Protocol and Export Considerations

For exporters and OEM integrators:

  • Label each port clearly: “CAN to Battery”, “RS485 to Meter”
  • Provide a pinout diagram or wiring guide
  • Ensure documentation lists supported BMS protocols (e.g., Pylontech CAN, LG RS485)
  • Offer tech support to help clients match inverter and battery communication

RS485 and CAN may seem invisible, but they’re foundational to the stability and intelligence of any PV+ESS system. Understanding the strengths and roles of both protocols will help small installers avoid communication faults and help exporters deliver truly compatible, ready-to-run solutions.

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