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Refoss Open API Smart Energy Monitor EM16P vs ABB B21 312-100

Install fit
Phase support Single-phase 2-wire, split-phase 3-wire, and 3-phase 4-wire Wye systems with grounded neutral; not for Delta systems. Single-phase, 220-240 V AC, 50/60 Hz.
Installation Indoor electrical-panel CT installation with clamp-on main and branch-circuit sensors. Indoor 2-module 35 mm DIN-rail direct-connected installation; IP20 meter for qualified-electrician panel wiring.
Measurement CT-based whole-home and circuit-level energy monitor with consumption, feed-in, voltage, current, power, power factor, and energy statistics. Direct-connected single-phase active/reactive energy and electrical-parameter metering with separate import/export registers.
Max current 200 A 65 A
Meter fit
Accuracy class +/-2% measurement accuracy MID Class B / IEC Class 1 active energy; Class 2 reactive energy.
Current sensing 2 main CT sensors up to 200 A each plus 16 branch-circuit CT sensors up to 60 A each. Built-in direct current path rated 0.25-5(65) A; no external current transformer required.
Monitoring
Protocol Wi-Fi / local Web UI / Refoss Open API / MQTT / Home Assistant RS-485 Modbus RTU / EQ Bus / S0 pulse outputs
Local API Yes Yes
Cloud dependency Cloud optional; offline local Web, Open API and MQTT work without app or registration. Refoss cloud is used for remote charts and long-term history. No vendor cloud required; measurements are read locally over RS-485 Modbus RTU, EQ Bus, S0 pulse, or the front display.
Home Assistant Yes Yes
Solar fit
Solar import/export Yes Yes
Buying context
Price range USD 159.99 sale / USD 199.99 regular EUR 420 gross list price from ABB Netherlands; net price, tax, stock, and regional distributor pricing vary.
Availability United States and Canada through Refoss official online store; broader availability depends on regional store and reseller channels. ABB global product and distributor channels; current Netherlands official channel listing verified, with regional stock and certifications varying.
Source check
Last verified Oct 11, 2026 Oct 14, 2026
Product page Official page Official page
Documentation Official docs Official docs
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