Home energy monitor systems measure and log the total amount of energy used in the home. Connect the system to your home network and you can view the details of home energy use on any computer. Smartphone apps are available for some systems that allow you to monitor your energy use from most anywhere. Creative graphics are used to display the information making energy use easy to understand.
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There are a variety of home enegy monitors that have a web presence but only a handful that have been commercially available in the U.S market long enough to establish their own track record. Our discussion will focus only on those units that have built a reputation. As new products emerge, we will evaluate and include them as they establish their own merit in the market place.
Home energy monitors can be subdivided into three categories, namely single-point measurement, multi-point measurement and circuit level measurement. Our Smart Meters page organizes the product specification tables in this manner for a better "apples-to-apples" comparison between home energy monitors.
Single-point units simply measure power at one location as it enters the circuit breaker panel. Multi-point units also measure the main feeder but have additional channels than can measure sub-panels or large appliances. 120/240 volt split phase power requires two channels while 120 volt single phase power only requires one channel. Most single and multi-point monitors use double channels.
Circuit level measurement refers to monitors that can measure a minimum of all 40 circuits found in a standard 200-amp panel. These systems consist of modules that typically measure 12 to 16 circuits each. The modules are linked together to measure the total number of circuits desired.
Regardless of category, each channel requires a current transformer or CT to be installed around the conductor to the circuit being measured. In the case of a circuit level monitor, the wiring inside the circuit breaker panel can get rather busy as shown here:
Pricing of home energy monitors varies directly with the number of circuits they can measure. Single point monitors are the least expensive, followed by multi-point with circuit level carrying the highest cost. Since each channnel requires a separate CT to measure, hardware cost increases with the number of circuits measured. Software sophistication also increases with additional circuits to measure.
Although, this level of sophistication comes at a higher price, the finer level of detail it provides may be well worth the additional investment for larger homes. This brings us to the question of "How much should I spend on a home energy monitor system?" Our recommendation is to keep the total cost below twice that of your average monthly electric bill.
For example, if your average electric bill is $200, your home energy monitor investment should be less than $400. You could purchace a nice multi-point energy monitor for this amount. If you have a larger home or you live in an area that has very high rates, you average bill may be over $500 per month. At twice that amount you could get started with a circuit level monitor.
The reason we recommend twice your monthly bill as a budget is that if you can save a conservative eight to ten percent each month, you will recoup your investment in less than two years. If you are comfortable with a longer pay back period do consider the higher end circuit level unit. You may find the added circuit level detail will allow you to save 15-20 percent instead, still keeping your pay back period under two years.
Starting on the right-hand side of the diagram, power is measured at the main panel as electricity enters the home. From the panel, data is transmitted to an Ethernet IP gateway or display using power line communications, wireless or a hard-wired connection.
The gateway analyzes the data if it has an internal web server or sends it to a remote server on the Internet. This data can be viewed with a remote display or on any computer connected to the local home network. Historical trends allow you to view home energy use over a period of minutes, hours, days, weeks or months.
As an alternative to Ethernet IP most single-point monitors just connect the measurement unit directly to the display. If a computer interface is available, the display uses a USB cable to transfer home energy use data to the the PC for analysis with vendor supplied software or spread sheets. These lower cost units do provide whole house electrical data to a single computer but do not provide IP network access.
The more sophisticatad circuit level monitors add a CT to the load side of each circuit breaker within the panel. These CT's typically terminate in a module located next to the panel. The module does initial processing of the electrical data and sends it to a gateway or remote web server for subsequent viewing.
Each energy monitor manufacturer uses their own strategy to measure, process, communicate and display the electrical data. For more information on specific monitors please visit our Smart Meters. For software visit the Dashboards page. If you are trying to decide whether to hire an electrician or do the work yourself check out the Power Meter Installation page to see what is involved.
If you have developed a residential monitoring system or know of one that is commercially available in the U.S. that is not listed on the Smart Meters page, please contact us if you would like to have it evaluated for inclusion on this site.