Split Single-phase Energy Meter

by CircuitSetup

Affordable remote energy monitoring for your entire home

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of $6,300 goal

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Product Choices


Energy Meter Board

Perfect for building your own energy monitoring system. Hook up our energy meter to your MCU, current & AC transformers, load the software, and start monitoring!


Energy Meter Kit

Comes with Energy Meter, 2x 16 mm round YHDC SCT-016 120 A CT Sensors, Pre-programmed ESP32 Dev Module, 100x60x25 mm ABS plastic box, PCB ESP32 box adapter, and mounting screws. Everything you need to connect the energy monitor to your house and start monitoring your energy usage in no time. European customers must provide their own 9 V AC Transformers.


Solar Monitoring + Energy Meter

If you want to monitor your solar power generation and energy usage at the same time, this is the package for you! Comes with 2x Energy Meters, 4x 16 mm round YHDC SCT-016 120 A CT Sensors, PCB ESP32 adapter, Pre-programmed ESP32 Dev Module. European customers must provide their own 9 V AC Transformers.


Recent Updates

As Featured In

The Split Single-phase Energy meter is part of the Microchip Get Launched design competition!

The CircuitSetup Split Single-phase Energy Meter is an affordable, accurate, remote energy monitoring device for your entire home. It can monitor energy usage in real time, independent of your power utility’s meter, and can be easily hooked up to any wireless micro-controller (like an ESP8266, or ESP32) to transmit energy data into a program like EmonCMS. It can also be used to monitor solar systems to keep track of how much power you are generating from the sun. It uses safe current transformer clamps to sample current - no AC wiring is required.

Split Single Phase Energy Meter

Take charge of your energy usage

With the Split Single-phase Energy Meter you can:

  • Save Money
    • See exactly how much money you're spending on energy in real time
    • Find appliances that are using too much electricity
    • Calculate energy usage for a single room to divide an energy bill fairly among roommates
  • View & Gather Energy Data
    • View the energy usage of your entire home
    • Track solar power generation (two units required)
    • Calculate how much it costs to charge your electric vehicle
    • Remote energy monitoring for vacation or rental properties
    • Review and graph historical energy data
  • Be Informed!
    • Independent of your power utility's meter
    • Set up alerts for over- or under-usage
    • Prevent surprises on energy bills
    • View usage data in the EmonCMS Android or iOS apps
    • Automate notifications with your home automation system like "send my phone a message when the dryer is done", or even "if I leave the house, and the oven is on, send me an alert" (programming required)
  • Spend less on energy monitoring hardware!
    • Affordable but very accurate
    • Save hundreds over popular monitoring systems

Split Single Phase Energy Meter Kit

Control Your Energy Bill

For Homeowners

Have you ever gotten a bill from your energy company and said "What the… why is this so high? What is using all of this electricity?!" We’ve all been there. Then you go looking for the cause of the problem after the fact. "It’s that sump pump/old fridge/AC unit again…" What if you could find out what is using too much energy, and turn it off, before you get the bill? With our energy meter, you can.

You know your new Tesla is saving you on gas, but do you know how much it costs to charge over a month/week/year? With our energy meter, you can.

Your son constantly plays video games. You told him to cut back, and he insists that he has, but you suspect he’s playing games late at night. That GPU of his uses a ton of electricity! What if there was a way to tell without invading his privacy? What if you could even tell how long over time he’s been playing by looking at a graph? With our energy meter, you can.

For Renters

Your roommate insists that his mining rig "doesn’t use that much juice because he tuned the GPUs", and he only owes \$100 of your \$400 bill. Never-mind that he has 3 extension cords going across the apartment because one 15 amp circuit wasn’t enough. What if there was a way to calculate exactly how much energy your room is using without spending \$300 on monitoring hardware? With our energy meter, you can.

For Landlords

In the winter, it’s vital that the pipes under the addition in your rental property do not freeze. To solve this problem, you’ve installed an electric pipe heater. It works great, when it’s working! It sometimes trips a breaker if too many things are on in the house, and you’ve had one fail before. What if you could monitor the pipe heater without driving 45 minutes to check on it? With our energy meter, you can.

For Businesses

You just purchased a new manufacturing machine, but one thing you didn’t calculate into the ROI is the electricity that it uses. You overlooked the fact that it has seven different high torque electric motors spinning 24/7. What if you could more accurately calculate ROI on that new machine? With our energy meter, you can.

Features & Specifications

  • IC: MicroChip ATM90E32
  • Connectivity
    • SPI Interface to connect to any Arduino compatible MCU
    • Two IRQ interrupts, and one Warning output
    • Energy pulse output (pulses correspond to four LEDs)
    • Zero crossing output
  • Real Time Data Sampling
    • Two current channels
    • One voltage channel (expandable to two voltage)
    • Measurement Error: 1% when calibrated
    • Dynamic Range: 6000:1
    • Gain Selection: Up to 4x
    • Voltage Reference Drift Typical (ppm/°C): 6
    • ADC Resolution (bits): 16
  • Calculates
    • Active Power
    • Reactive Power
    • Apparent Power
    • Power Factor
    • Frequency
    • Temperature
  • Other Features
    • Can use more than one at a time to measure as many circuits as you want, including solar power generation
    • Uses standard current transformer clamps to sample current
    • Includes built-in 500mA 3v3 buck converter to power MCU board
    • Compact size at only 40 mm x50 mm

Open Source

All aspects of this project are open source. The software and pcb design files are published in our Github repository. User contributions are encouraged and will only help the home automation and DIY electronics community as a whole.

Being open source allows users to be very flexible with everything from the firmware that is on the energy meter, and where it is sending data, to easily changing what micro-controller is powering it. You don’t have to pay for upgrades or subscription fees if you don’t want to. You also don’t have to rely on a company to keep your data safe.


EmonCMS was chosen as the primary software package due to its open source design, robustness, and surrounding community. It’s intuitive, easy-to-use, and a great fit for our purposes. The OpenEnergyMonitor project was a large inspiration for the creation of our energy meter.


With EmonCMS you can view up to the second live graphs, detailed historical graphs, solar generation/usage data, and with their Android and iPhone apps, live energy usage data on your phone.

EmonCMS Solar Graph

EmonCMS Graph

EmonCMS Graph 2

You can easily see your energy usage and amount you’re spending:

EmonCMS Watts

EmonCMS Usage Cost

EmonCMS can be installed on a local machine (like a Raspberry Pi) or on a remote machine running a web server. You can also use OpenEnergyMonitor’s services, which when configured with the Split Single-phase Energy Meter, costs roughly $15 a year.

Alternatively, you can send energy usage data anywhere you want using MQTT or JSON. This includes smarthome apps like Smartthings and HomeAssistant. The example Arduino sketches in our Github repository include information on how this can be accomplished.


To gather energy data, the Split Single-phase Energy Meter uses current transformers (CTs) attached around the two main power wires coming into your breaker box. They simply clip around the wires to measure the current flowing through the wires. There is no metal to metal contact. Many energy meter products require being wired into the breaker panel, or must have a secondary DC adapter to power the unit. This energy meter does not require either.

current transformer

An AC transformer reduces the AC voltage down to a level the energy meter can safely read. There is no high voltage going into the board. This allows for accurate measurement of voltage, which is then translated into watts and kilowatt hours. The on-board buck converter also takes the power from the AC transformer and turns it into a usable DC power source for the board and controller via a 3V3 output.

Split Single Phase Energy Meter

For measuring solar generation and usage, the solar package comes with a second energy monitor, set of CTs, and AC transformer. The CTs hook to the wires coming from your solar transformer and going into your main breaker panel.

For US customers we can provide the 9 V AC transformer(s) in the two package options. Since there are different outlet options in Europe, customers will have to provide their own AC Transformer. Two AC Transformers that we recommend are the Ideal Power Ltd. 77DE-06-09 (Euro plug), and the 77DB-06-09 (UK plug).


Product Connectivity Real-Time Powered by... Open Source Voltage Power Factor Accuracy
Split-phase Energy MonitorWi-Fi, BLE, LoRa, 3G Yes AC Transformer Yes Yes (2) Yes 99% or better
SenseWi-FiYes Wired to panel No Yes Yes 99%
EmonPiWi-Fi, RadioNo DC Adapter Yes Yes No (asynchronous sampling) Depends on CT
Eyedro EYEFI-2Wi-FiYes DC Adapter No Yes Yes Depends on CT
Neur.ioWi-FiYes Wired to panel No Yes Yes 99%
Efergy True Power w/ hubRF w/ Wi-Fi Gateway No Batteries No No Yes99%

Support & Documentation

Detailed documentation on the Split Single-phase Energy Meter can be found in our Github repository

If you have a question about ordering, paying, or shipping, please refer to The Crowd Supply Guide.

If you have a technical question about the operation of the Split Single-phase Energy Meter or any of its applications, please ask the creators your question directly using the Ask A Question button below.


Precautions have been taken to isolate the Split Single-phase Energy Meter from mains AC power using current and voltage transformers. Power on the circuit board itself is low voltage & current. However, the energy meter has current sensors that connect around mains AC power. High voltage AC power is dangerous! If you are not comfortable working around AC voltage, we strongly encourage you to hire a qualified electrician.



CircuitSetup's goal is to make affordable and useful electronic components available to makers, and DIY electronics enthusiasts. Our products are carefully crafted, tested, and re-tested to make sure they meet the demands of their users.

John Deglavina

Founder & Product Designer

See Also

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