Energy Use Cases · Branch Circuit Monitoring
Shelly Pro 3EM Branch Circuit Monitoring: Why Choose ecoMain?
Already using Shelly Pro 3EM and want to see what your heat pump, EV charger and other circuits consume? For multiple circuits in one electrical panel, ecoMain is our recommended next step: keep Shelly at the mains, add ecoMain for branch monitoring, and bring both into Home Assistant.
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Target energy devices
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The advantage is how the system grows. ecoMain brings multiple measurement channels together around one network-connected host, with ecoSub modules adding capacity as needed.
Start with your most important loads, then expand without replacing your existing Shelly installation.
Why Add Branch Monitoring to Shelly Pro 3EM?
Installed at the grid connection, Shelly Pro 3EM tracks mains power, grid import and export. It also supports suitable branch measurement points, Ethernet and Wi-Fi. See the official Shelly Pro 3EM documentation.
A meter at the mains cannot separately measure every downstream circuit from the total alone. When evening power rises, branch readings help you see whether the EV charger, heat pump or water heater is responsible.
With ecoMain, the circuits that matter get their own measurement points, turning one overall curve into useful load-by-load information.
Shelly Pro 3EM vs ecoMain: How Should You Expand?
| What matters | Additional Shelly Pro 3EM meters | ecoMain + ecoSub |
|---|---|---|
| Adding circuits | Add separate meters for new measurement points. | Add sensors, then expansion modules as needed. |
| Network management | Connect and manage each meter separately. | Multiple channels share one network-connected host. |
| Supply connections | Each meter needs its supply / voltage-reference connections. | One central supply; ecoBus powers the expansion modules. |
| Home Assistant | Shelly integration. | enecess integration with local access. |
| Best fit | A few independent or separately located measurement points. | Multiple circuits in one panel, with room to grow. |
For a growing circuit count in the same panel, ecoMain combines centralised connections with modular expansion.
Why ecoMain Fits a Growing Branch Monitoring System
Multiple Circuits, One Network Connection
Each independent networked meter is another device to configure and manage. With ecoMain, multiple channels connect through one host.
For example, 14 three-channel meters provide 42 measurement channels and create 14 network clients. One ecoMain with three ecoSub modules uses one network connection for the monitoring system. Your existing Shelly keeps its own connection.
Centralised Supply and Expansion Wiring
In the configuration below, each independent meter uses four supply / voltage-reference conductors: 14 meters require 56 individual wire runs. ecoMain uses one five-conductor supply / sampling connection, with three ecoBus cables carrying power and data to the expansion modules.
For the selected modules, DIN-rail allocation is 14P for 14 independent 1P meters, compared with 10P for ecoMain (4P) and three ecoSub modules (2P each)—a reduction of 4P, or about 29%. This excludes sensors, terminals, cable ducts and clearances. If each meter uses LAN, network cables fall from 14 to one; Shelly also supports Wi-Fi.
Start Small and Add Channels as Needed
Begin with the heat pump, EV charger and water heater, then add other circuits when useful. Each ecoSub module adds 10 channels, with support for up to three modules in a cascade.
The largest listed three-phase ecoMain kit includes three mains sensors and 40 branch sensors: 43 measurement channels in total.
Use Case: Solar, a Heat Pump and an EV
In a typical solar home, keep Shelly Pro 3EM at the mains and use ecoMain for the key branches:
- Find high-consumption loads. Compare heat pump, EV and water heater trends to understand overnight demand and review schedules.
- Use more solar energy at home. Combine grid import/export and PV generation with branch readings to identify loads that could run during daylight hours.
- Improve automation inputs. Use Home Assistant to combine solar surplus, mains load and branch measurements when controlling compatible devices.
A shared circuit reports the combined consumption of its appliances. Savings depend on tariffs, solar output and how loads are used. ecoMain provides measurements; compatible controllers perform the actions configured in Home Assistant.
Connect Shelly Pro 3EM and ecoMain to Home Assistant
Connect both systems separately, then organise their data in one dashboard.
- Keep Shelly connected. Add or check it using the Home Assistant Shelly integration.
- Add ecoMain. Follow our ecoMain Home Assistant guide. Local Modbus TCP access requires supported firmware and a reachable local network.
- Map your channels. Name each circuit and sum the relevant channels for multi-phase loads.
- Verify the readings. Check energy units, import/export direction and channel mapping against a known load.
| Dashboard measurement | Data source |
|---|---|
| Grid import and export | Existing Shelly Pro 3EM |
| Solar PV generation | ecoMain channels or suitable inverter data |
| Heat pump, EV charger and other loads | ecoMain / ecoSub branch channels |
Branch consumption is already included in household consumption; do not add it again to the total. See the enecess integration documentation for current software requirements.
Choose Single-Phase or Three-Phase ecoMain
Choose sensors for your single-phase supply and important circuits.
View single-phase ecoMain →
Build your system around your phases and channel requirements.
View three-phase ecoMain →
Add channel capacity when the existing channels are no longer enough.
View ecoSub →Choose the version for your electrical supply and reserve enough channels for the circuits you plan to monitor. Add ecoSub when you need more capacity.
Have a qualified electrician confirm sensor compatibility, rated current, opening size, phase mapping and panel conditions using the product manuals.
Make Every Important Circuit Visible
Already have Shelly Pro 3EM? Make your next upgrade circuit visibility. With centralised measurement and modular expansion, ecoMain helps you see where your energy goes as your system grows.
Frequently Asked Questions
Do I Need to Replace My Shelly Pro 3EM?
No. Keep it for mains monitoring and add ecoMain for important branch circuits. View both through Home Assistant.
Does ecoMain Need Cloud Access for Home Assistant?
No. Local Modbus TCP access is available with supported firmware and network configuration. Follow the setup guide.
How Many Channels Does a Three-Phase Load Need?
Normally three. Multiple appliances on one shared circuit are measured together, so plan channels around your wiring and measurement goals.