“With Google PowerMeter integration and an iGoogle widget, I can use eGauge to track my energy usage and solar generation from my iPhone! Neat!”
Colin McGraw, Caelestis Consulting

eGauge Overview

eGauge is an affordable, flexible, secure, web-based electric energy and power meter that can measure up to 12 circuits on up to 3-phases (120V−480V, 50−60Hz). Use it to measure and record whole-house consumption, solar, wind, and other renewable electricity generation, measure consumption of individual loads, such as appliances or the consumption of geothermal system pumps and backup heaters. The data can be viewed on any web-enabled device through the built-in web-server. The display is updated every second, giving immediate feedback on any load or generation changes. The device records the most recent 30 years of data in its built-in solid-state memory. The measurements can also be accessed through BACnet and/or can be pushed to a server via an XML API.

Benefits

Installing an eGauge often pays for itself in a short amount of time.

Optimize your carbon footprint

Track your usage and compare it on a single screen to your renewable energy generation, helping you achieve net-zero energy consumption, maximize your payback, and lower your monthly electricity bill.

Lower your peak demand

With second by second updates, you will immediately see major loads turning on and off. Giving you the tools needed to minimize peaks.

Monitor your system health remotely

Since eGauge is accessible through the Internet at no extra charge, you can easily check on your home and/or renewable energy system while travelling.

For renewable energy-system installers, our eGuard Manager service provides a convenient way to monitor all your installed systems on a single screen and detect failures even before your customers do.

Measure individual appliances

Use a single eGauge to meter up to twelve separate circuits or gang multiple eGauge together for virtually unlimited capacity. Measure individual loads (AC, fridges, geothermal pumps), individual apartments, hotel-rooms, etc.

Hardware Components

Mouse over the individual hardware components in the image below for a description of the components function:

The eGauge main unit (i) measures voltage on up to three channels, (ii) current on up to twelve channels, (iii) calculates power and energy, (iv) stores the measurements on its built-in solid-state memory, and (v) provides access to the data via its built-in web-server, XML-based push API, and/or BACnet.

Up to twelve Current Transformers (CTs) can be plugged into a single eGauge. Each CT senses the current flowing through its doughnut hole. Normally, a single wire is run through each CT. If multiple wires run through the CT, it will measure the sum of the currents (if they are in phase). All of our CTs have a 'split-core' design, which allows them to be opened up and slipped over an existing wire without having to disconnect the wire first. Together with the measured voltage, eGauge uses the measured current to calculate the power and energy flowing to or from a device, such as an appliance, solar or wind inverter, or the electric utility's grid.

eGauge is wired to a dual-pole breaker (US residential installation) or three-pole breaker (3-phase installation). The breaker (i) powers the eGauge device, (ii) allows eGauge to measure the voltage on each leg/phase, and (iii) provides the means for eGauge to communicate with the LAN. eGauge draws less than 100mA of current, so the smallest breaker available will be fine. For US installations, a 15A or 20A breaker is commonly used.

The HomePlug adapter communicates with eGauge over the existing power lines in the home/building. To work properly, it is best to plug the adapter directly into a wall-outlet. The outlet should be within about 100 feet of the eGauge device. The adapter itself is connected to the LAN through a standard Ethernet cable. Usually, the Ethernet cable is plugged into an existing router/modem or Ethernet hub/switch. HomePlug is an industry-standard. If you already own a HomePlug 1.0-compatible adapter, there is usually no need to buy another one for eGauge.

Any LAN-connected device with an available Ethernet port can be used to attach the HomePlug adapter. Normally, an existing DSL/cable-router or Ethernet hub/switch is used for this purpose. If all Ethernet ports are occupied, a low-cost 5-port Ethernet hub can be used to extend the number of available ports.

The data collected by eGauge can be displayed on any web-enabled device, including desktop-computers, Internet tablets, and iPhone, Google Android, and other smartphones. The built-in web-server can be accessed through the LAN or through the Internet. To access an eGauge from the LAN, simply type the device-name into your browser's URL bar (Windows) or enter the device-name followed by '.local' (Mac and Linux computers).To access a device from the Internet, enter the device name in the browser's URL bar, followed by 'egaug.es'. There is no service fee for accessing the device through the Internet.

Metering Capabilities

eGauge samples each measurement channel several thousand times a second in order to calculate real power (what the utility bills you for), apparent power, True RMS voltage, and current. The high-frequency and simultaneous sampling allows eGauge to establish the phase-relationship between the voltage and current channels and therefore it can detect which direction power is flowing (e.g., from grid to house, when power is being consumed, or from house to grid, when renewable-energy generation is greater than usage in the house).

Once a second, eGauge updates the following quantities:

Line frequency in Hertz (one measurement).
True RMS voltage in Volts (one measurement per voltage tap).
True RMS current in Ampères (one measurement per CT).
Real power in Watts (one measurement per voltage/current pair defined in the device configuration).
Apparent power in VA (one measurement per voltage/current pair defined in the device configuration).
Power factor (one measurement per voltage/current pair defined in the device configuration).

The eGauge web interface provides a live view of these quantities through the channel checker (Tools→Channel Checker).

The eGauge Web Interface

The main screen of the eGauge web interface presents current consumption and generation info with a live, high-resolution graph:

The left portion of the graph displays recent historical data (most recent 48 hours in the example above), whereas the right portion is a gauge that is updated each second and displays current generation (green) and consumption (red). In the example above, at the time the snapshot was taken, the solar system was producing 6913 Watts of power while total consumption at the house was 6016 Watts.

The thick red line indicates total consumption whereas the thick green line indicates total generation. The red shaded area indicates the amount of energy consumed from the grid whereas the green shaded area indicates the amount of energy put back onto the grid.

Kiosk View

By clicking on the "Kiosk" link at the top right of the main screen, the display is switched to the kiosk-view. This view is designed for non-interactive displays such as an entry-lobby or a kitchen tablet computer. It automatically cycles through three screens: the first screen shows renewable energy generation since midnight. The second screen shows renewable energy generation since the eGauge was installed. The third screen shows a simplified version of the graph that is shown on the main screen.

For a moderate fee, the kiosk-view (as well as other aspects of the Web interface) can be customized. For example, the screenshot below shows a version of the interface that was developed for the Denver Botanic Gardens:

Web-based Configuration

Virtually every aspect of an eGauge's operation can be configured through the web-interface. Access to these screens is protected through a password that needs to be entered before saving any changes.

The screenshot below shows the Installation screen, which defines what kind of CTs are connected to the eGauge, what energy data (Registers) to record, and how total consumption and generation are to be calculated:

For more detail and many examples of typical configurations, see the eGauge Configuration Guide, available in the Support section of this web page.

BACnet

For building automation and control, eGauge supports the BACnet protocol. Using the eGauge BACnet setting screen (Settings→BACnet), the BACnet device id can be selected and eGauge can configured to use either the BACnet/IP (BIP) or BACnet/Ethernet data-link layers.

eGauge provides access to the current (second-by-second) measurements through the following Analog Input object groups:

Group Number: Number of first object in group: Description:

1 0x20000: Voltage [V].

2 0x30000: Current [A].

3 0x50000: Line frequency [Hz].

4 0x60000: Timestamp [s].

5 0x70000: REGVAL [various].

6 0x80000: REGCHG [various].

Group 1

The RMS voltage of the voltage-taps can be read through this group. Object ID 0x20000 corresponds to L1, 0x20001 to L2, and 0x20002 to L3.

Group 2

The RMS current measured by each CT can be read through this group. Object ID 0x30000 corresponds to CT1, 0x30001 to CT2, and so on, up to 0x3000b for CT12.

Group 3

The frequency of the voltage-taps can be read through this group. Object ID 0x50000 corresponds to L1, 0x50001 to L2, and 0x50002 to L3.

Group 4

0x60000 is the only valid object ID in this group and it reports the number of seconds elapsed since the BACnet daemon was started up. The BACnet daemon starts up either after freshly enabling BACnet support or after power-cycling or rebooting eGauge.

Groups 5 and 6

In these groups, the first few object IDs refer to the virtual registers (including totals), one per virtual register. This usually includes "Total Usage" and "Total Generation", along with any other virtual registers defined in the "Totals and Virtual Registers" section of the Settings→Installation screen. Subsequent object IDs correspond to the physical registers as defined in the "Registers" section of the eGauge Installation screen. The register name for a given object ID can be obtained by reading the "name" property (BACnet property 85) from the object ID.

Group 6 reports, for each virtual and physical register, the change in register value during the most recent one-second interval. The physical unit of this register depends on the quantity being recorded and can be obtained by reading the "unit" property (BACnet property 117) of the respective object id. For example, for a register recording power, the unit would be Watts, for a register recording voltage, the unit would be Volts.

Group 5 reports the register value for each register (virtual and physical). The register values are time-weighted values and hence the unit of these object IDs is equal to the unit of the corresponding object ID in Group 6, multiplied by seconds. For example, for a register recording power, the Group 6 unit would be Watts, and therefore the Group 5 unit would be Watt-seconds (i.e., Joules).