What is the purpose of the USB-C port vs. the RJ45 port on Alva LINK?

Each port on Alva LINK serves a distinct function. There are no redundant or decorative connectors.

USB-C — Power delivery

The USB-C port is how Alva LINK receives electrical power. It ships with a USB-C cable and power adapter in the box. This is the only thing you need to plug in to turn the device on. USB-C was chosen over barrel jacks or proprietary connectors because it's a universally available standard, if you ever need a replacement cable, any USB-C cable will work. The power draw is low (comparable to a phone charger), so placement near any standard outlet is sufficient.

RJ45 / Ethernet — Wired data connection to your energy asset

The RJ45 port carries Modbus TCP/IP over standard Ethernet to your energy hardware. This is how Alva LINK talks to heat pumps, solar inverters, home batteries, and EV chargers that support Modbus TCP. A single Ethernet cable runs from Link to your asset's Modbus port. The connection is local, deterministic, and does not pass through your home router — it's a direct point-to-point link between the controller and the device it manages.

Why wired Modbus instead of wireless? Reliability. Modbus TCP/IP over Ethernet is the industrial standard for energy equipment communication. It introduces no packet loss from Wi-Fi interference, no pairing failures, no Bluetooth range limits. The control signal from Alva LINK to your heat pump travels over a shielded cable with sub-millisecond latency. This is the same protocol that commercial building management systems use — proven across millions of installations worldwide.

RS-485 — Serial connection for legacy hardware

Alva LINK also includes an RS-485 serial interface for Modbus RTU communication. Many heat pumps expose Modbus RTU over RS-485 rather than TCP/IP over Ethernet — this is particularly common in older models and in the European installed base. The RS-485 connection uses a different cable type (typically a shielded twisted pair) and communicates at standard baud rates. This ensures backward compatibility with energy hardware that predates Ethernet-based control.

SG-Ready dry contacts — For the simplest heat pumps

For heat pumps that support only SG-Ready (a simple 2-wire on/off signalling standard common in Germany and expanding across Europe), Alva LINK provides dry contact outputs. SG-Ready defines four operating states: normal, reduced, recommended on, and forced on. This is the most basic level of control — less granular than Modbus, but sufficient for load-shifting the heat pump between cheap and expensive hours.

In plain terms: USB-C powers the device. RJ45 connects it to your energy hardware over Ethernet. RS-485 connects it to older hardware over a serial cable. SG-Ready connects it to the simplest heat pumps with basic wires. Wi-Fi connects it to the cloud. Bluetooth sets it up. Every port has a job.