Refoss EM16P Review (2026)

Specs at a Glance

What Makes the EM16P Different

The EM16P’s defining feature is architectural: it was designed from the ground up to work locally. While most consumer energy monitors treat local operation as an afterthought or a community hack, Refoss built the EM16P with a local Web UI, MQTT broker support, WebSocket API, and native Home Assistant integration as first-class features. This is not a cloud device with a local mode bolted on. It is a local device that happens to also offer cloud connectivity for users who want it.

This architectural difference has practical consequences that extend beyond privacy. When your internet goes down during a storm, the EM16P keeps monitoring. When you want to build a custom energy dashboard in Grafana, the open API gives you raw access to every sensor reading. When you want to automate your water heater to run only on excess solar, Home Assistant can read the EM16P’s data and trigger the relay without routing through any external server. The device simply works within your home network as a self-contained monitoring platform.

Accuracy and Measurement Quality

The EM16P is rated at plus or minus 1 percent accuracy, which is tighter than the Emporia Vue 3’s plus or minus 2 percent and close to commercial-grade metering. In practice, this means the EM16P’s readings track utility bills very closely, and the higher accuracy is especially noticeable on lower-draw circuits where a 2 percent margin can represent a meaningful absolute difference.

The branch circuit CT sensors are rated at 60A, compared to the Vue 3’s 50A sensors. This is a modest but real advantage for homes with high-draw 240V circuits, such as some electric dryers, ranges, or EV chargers that draw more than 50A during peak operation. For the vast majority of residential circuits, both sensor ratings are sufficient, but the EM16P’s wider range provides a small safety margin.

Installation

The physical installation follows the same clamp-on CT approach as other panel-mounted energy monitors. The 16 branch circuit sensors and two main sensors wrap around individual wires inside your panel without cutting or splicing. The process takes 30 to 60 minutes depending on your panel layout.

The EM16P connects directly to two breakers in your panel for power (Phase A and Phase B), which is a different approach from monitors that plug into a standard outlet. This means the device draws power directly from the panel rather than requiring a nearby receptacle, which simplifies placement but requires working with the breaker connections during installation. The included instructions walk through this process, though they assume more electrical familiarity than Emporia’s step-by-step app-guided setup.

One hardware advantage is the external high-gain WiFi antenna. Electrical panels are metal enclosures that often attenuate WiFi signals, and the EM16P’s external antenna helps maintain a reliable connection. The antenna routes through a knockout or gap in the panel cover, and Refoss includes a rubber grommet for the passthrough. Some users have noted that the included grommet does not fit all standard knockout sizes, so you may need to source an alternative grommet or use silicone sealant for outdoor panels.

The same safety considerations apply as with any panel-mounted monitor: the service entrance conductors remain energized with the main breaker off. If you are not comfortable working near live conductors, hire a licensed electrician.

Home Assistant Integration

The EM16P’s native Home Assistant integration is its strongest differentiator from the Emporia Vue 3 and most other monitors in this price range. After updating the device firmware through the Refoss app, you add it through the Home Assistant integrations page, and every sensor appears as an entity in your dashboard. Main line readings, individual circuit readings, voltage, and power factor are all available as real-time entities that you can chart, log, and automate against.

The practical value of this integration becomes clear when you start building automations. You can send a notification when your HVAC draws more than a set threshold (which may indicate a failing compressor or a filter change due). You can trigger a smart plug to turn off when a circuit exceeds a watt limit. You can log every reading to InfluxDB or another time-series database for long-term analysis at whatever resolution you want. None of this requires any cloud service, any subscription, or any firmware modification.

For homeowners who run Home Assistant but do not yet have an energy monitor, the EM16P slots directly into Home Assistant’s Energy Dashboard, which provides built-in visualizations for consumption, solar production, and grid usage. This built-in dashboard is not as polished as the Emporia app, but it is deeply customizable and runs entirely on your local Home Assistant instance.

Open API and Local Control

Beyond Home Assistant, the EM16P exposes its data through multiple open protocols. The MQTT interface publishes sensor readings to any MQTT broker on your network, which means the data can flow into Node-RED, Grafana, InfluxDB, or any other platform that speaks MQTT. The WebSocket API provides real-time streaming data for custom applications. And the local Web UI offers a browser-based interface for checking readings without any app or platform at all.

The local Web UI is worth highlighting because it provides a zero-dependency fallback. If your Home Assistant instance is down, if you are troubleshooting from a laptop, or if a household member just wants to check the current reading without installing an app, the Web UI works from any browser on your local network. It is not as feature-rich as a dedicated app, but it is always available as long as the EM16P is powered on.

For privacy-focused homeowners, the combination of local operation and open protocols means you can block the EM16P’s internet access entirely at your router level. The device continues to function normally on your local network, and no energy data ever leaves your home. Circuit-level energy data reveals daily patterns (when you wake up, when you cook, when you are away), and keeping that data local is a legitimate privacy consideration that the EM16P handles better than any other monitor in its price range.

Solar Monitoring and Zero Feed-In

The EM16P handles solar monitoring the same way as other CT-based monitors: you place sensors on your solar circuit, and the device tracks production alongside consumption. The Refoss app and Home Assistant both show net metering data, production curves, and the balance between solar generation and grid consumption.

Where the EM16P adds real value for solar owners is its zero feed-in automation capability. When your panels are producing more electricity than your home is consuming, the EM16P can detect the surplus in real time. Through Home Assistant automations, you can then redirect that excess to specific loads: turn on your electric water heater, start charging an EV, run a pool pump, or top off a home battery backup system. The goal is to use your own solar production directly rather than exporting it to the grid, which is increasingly important as utility net metering rates decline in many areas.

This is not a theoretical feature. The Home Assistant community has well-documented blueprints for zero feed-in automations using the EM16P as the sensing device, and Refoss provides documentation on their site specifically for this use case. The automation logic runs entirely locally on your Home Assistant instance, with no cloud dependency.

Refoss App

The Refoss app (available on iOS and Android) provides the basic monitoring interface for homeowners who are not using Home Assistant. It shows real-time readings for all monitored circuits, historical data with daily-level granularity stored for up to five years, and CSV export for anyone who wants to analyze their data in a spreadsheet or external tool.

The app works adequately for basic monitoring but does not reach the level of the Emporia app in terms of design quality, data visualization, or features like bill forecasting and cost tracking. If you are choosing between these two monitors primarily on app experience, the Vue 3 wins clearly. The Refoss app is a functional tool rather than a polished consumer experience, and it shows in the interface design and the limited visualization options.

That said, the app is not the EM16P’s intended primary interface for its target audience. Most EM16P buyers are Home Assistant users who will interact with their energy data through HA dashboards, and for that workflow the app serves mainly as a setup and firmware update tool. Judging the EM16P by its app alone misses the point of the product.

What Could Be Better

The app is the most obvious weakness. While the Emporia Vue 3 offers bill forecasting, intuitive cost tracking, and polished data visualizations, the Refoss app provides basic charts and readings without the interpretive layer that makes energy data actionable for non-technical homeowners. If you are not using Home Assistant, the app is all you have, and it can feel sparse.

The documentation, while improved over earlier versions, still assumes a higher baseline of technical knowledge than most consumer products. Setting up MQTT, configuring the local Web UI, or integrating with Home Assistant are all simple for experienced smart home users, but a homeowner encountering these concepts for the first time will find the learning curve steeper than with the Vue 3’s app-guided setup.

The warranty is 2 years compared to the Vue 3’s implicit indefinite support through its cloud platform (Emporia does not specify a warranty duration but provides ongoing cloud service and firmware updates). For a device installed inside an electrical panel where replacement is inconvenient, a longer warranty would be reassuring.

Data retention in the Refoss cloud is limited to five years of daily-level data, compared to Emporia’s indefinite hourly data. This is less of a concern for homeowners running Home Assistant (since they can store data locally at any resolution and any duration), but for app-only users it is a meaningful limitation. The CSV export feature partially addresses this by letting you download your data for external storage.

How It Compares

The EM16P’s direct competitor is the Emporia Vue 3, and the comparison comes down to philosophy rather than hardware specs. Both monitors cost about the same, monitor the same number of circuits, and support solar. The Vue 3 is a consumer appliance designed to work seamlessly through a polished app. The EM16P is a platform designed to integrate into a technical homeowner’s existing smart home stack. Neither approach is wrong; they serve different homeowners with different priorities.

On pure specs, the EM16P holds small advantages in accuracy (plus or minus 1 percent versus 2 percent) and sensor capacity (60A versus 50A branch circuits). On ecosystem and ease of use, the Vue 3 holds a clear lead with its app quality, Alexa integration, and zero-configuration cloud storage. On openness and long-term independence, the EM16P has no competition at this price point.

For homeowners building a broader energy management system, the EM16P pairs naturally with the products in our Best Smart Thermostats guide through Home Assistant automations (for example, adjusting thermostat setpoints based on real-time energy consumption) and with home battery backup systems for load monitoring and solar optimization. For homeowners interested in indoor air quality alongside energy monitoring, our sister site ClearAirLiving.com covers air quality monitors that can also feed into Home Assistant dashboards for a unified home environment view. Our Best Whole Home Energy Monitors guide provides the full overview, and our Emporia Vue 3 vs Refoss EM16P comparison breaks down every difference between these two monitors in detail.

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