Electrical Energy Sub-Metering

The electrical utility has a meter at each site, which records the electricity consumed at the site, so that the site owner can be billed for the power used.  However, the measurements taken by the utility meter are typically only shared with the customer as a monthly total, with no information about which devices at the site used the power, or on which day of the month, or what time of day.  For most customers, the utility meter doesn’t provide any real-time power consumption information unless the customer can read and interpret the spinning disc or changing digits on the meter.

 

We have seen an increase in requests for energy metering from homeowners and business owners, for the purpose of identifying which devices are using the most power and reducing the amount of electricity being consumed.

 

Dandelion Renewables offers solutions for permanent energy meter equipment installation, as well as temporary energy metering equipment installation often combined with an energy efficiency study, as an approved Energy Assessment Provider with AB Agriculture & Forestry for the Farm Energy and Agri-Processing Program (FEAP), and as an ASHRAE Level 2 Energy Auditor listed by Alberta Energy Efficiency Alliance.

 

The cost of a “commercial grade” energy meter installation for historical consumption data analysis, whether permanent or temporary, is often only cost effective for large power consumers such as manufacturing plants, offices, warehouses, and farms.  Energy metering at an average sized home in AB, BC, or SK, typically warrants a lower price point solution.

 

The value of energy sub-meters comes from:

  1. Real-time power consumption awareness helping to influence adjustments of people’s habits and decisions around when to turn electrical devices on or off.
  2. Identification of how much power individual electrical equipment is using, to help with “return on investment” evaluations and decisions when to upgrade to more energy-efficient equipment and to invest in repairs or maintenance of equipment to reduce energy consumption.

 

After a recent search through energy monitoring systems available, here are our favourite systems, for various applications, in order of lowest to highest cost (and complexity):

  1. For Epcor customers only, who only want to see the real-time total home power consumption from the grid (not appliance-specific), we would recommend one of the utility-meter-interactive energy monitoring devices that Epcor has tested and listed on their website that claim to display and graph the power consumption measured by Epcor’s utility meter (~$100 to $200 +install without an electrician).
  2. For homeowners or small businesses (max 240VAC for North America, 200A or less, 1-phase or 3-phase) who want to see real-time total power consumption, without appliance-specific monitoring, and without the need for historical data analysis, we would recommend the Neurio (W1 HEM kit, about $300CAD +install), because (a.) it is one of the lowest cost systems available for monitoring the total energy consumed between the home and the power grid, (b.) the website has helpful support documentation, and (c.) Neurio is compatible with 3-phase power, found at some commercial sites, which allows a larger customer base and support community for all Neurio users.  A great feature of Neurio is the historical data granularity available for download from the web interface, for export to external spreadsheet software for more detailed analysis and reporting. The data export format isn’t very user-friendly (e.g. units such as watts don’t export with the data) but the data is accessible at granularity down to 5-minute time-buckets. The biggest limitation we see with the Neurio and similar competing lowest cost systems available (e.g. Aeotec, Eyedro, Smappee, Sense) is that it becomes relatively expensive (and limited) if someone wants to add monitoring of more than just the one main power circuit of the home and solar power generation.
  3. For homeowners or small businesses (240VAC, 100A or less, 1-phase only) who want to monitor three or more circuits, we recommend the energy CURB.  It has user-friendly and thorough graphing features through a web portal and a smartphone app, and official compatibility with SmartThings (a smart home automation hub).  The CURB costs about $625CAD +install (includes 18 circuit sensors). The user interface is well suited for both advanced users, and also users who just want a simple summary without being overwhelmed by details.  The biggest limitations we see with CURB is that it doesn’t work with currents above 100A, or voltages above 240VAC, or 3-phase power, and the data export time-granularity is fixed as hourly, which limits the usefulness of the exported historical data for analysis or reporting in external spreadsheet software.
  4. For large power consuming businesses or large homes (1-phase or 3-phase, any voltage, any current) focused on energy consumption data analysis, power quality (power factor) and monitoring multiple circuits, eGauge is a great choice, and costs about $650CAD + $40 to 120 per circuit +install. The web interface is excellent for historical data analysis “by the minute and second” for consumption, peak demand, and power factor.  The web view is powerful for graphical interactive analysis, even on a smartphone once you know your way around the web pages. The graphs include real-time and historical consumption for solar generation and power consumption in one interactive view, that easily adjusts between time-scales from seconds up to years.  The biggest downside we see with the eGauge is the lack of a smartphone app, and the complexity of the powerful user interface can take some time for new users to learn. Dandelion Renewables has been using eGauge equipment to help commercial sites monitor and reduce power consumption for years.

 

Noteworthy, are some solar PV inverter companies (e.g. Fronius, SMA, SolarEdge) that are working toward expanding their solar power generation monitoring tools to also measure power consumption for the site.  Fronius has a real-time consumption monitoring option with their energy meter accessory “Smart Meter” but with a price tag of ~$850CAD+install, it would only be suitable for users who want to do more with the Smart Meter, such as controlling the export of energy to the grid.  SolarEdge has a similar metering accessory but it doesn’t report real-time consumption information (15 min reporting delay). SMA has a similar energy meter accessory but it isn’t available yet in North America.

 – Steve Gladwin

Add Comment

Your email address will not be published. Required fields are marked *