Shelly 3EM-63T Gen3 is a compact breaker-adjacent energy meter for buyers who want more local visibility and automation flexibility than an app-only monitor usually gives. It is designed to monitor either a three-phase system or three independent single-phase circuits, making it a useful fit for advanced homes, solar-adjacent installs, workshops, and small commercial panels.
What makes it stand out is the combination of local access and compact physical fit. Shelly says the device can run standalone on a local Wi-Fi network, exposes an embedded web interface, supports MQTT, HTTP, WebSocket, and JSON-RPC style data export, and stores at least 7 days of one-minute interval data on the device itself. That makes it more attractive than a cloud-first monitor when the real goal is Home Assistant, local dashboards, or custom automation.
It is also photovoltaic ready and supports bidirectional measurement, so it can help track import and export behavior in solar-aware setups. The main caution is that the reviewed official guide specifies 220-240 V supply between phase A and neutral, so buyers should treat it as a better fit for panels and electrical markets that match that requirement rather than assuming it is a universal North American whole-home monitor.