IoTaWatt Energy Monitoring Device Review

Have you ever sat and wondered the amount of energy a given device in your house uses?  How about the energy use of your entire house?  You may have even purchased one of many devices like the Kill-A-Watt, so you can attach it to an outlet and connect a device like a TV to see how much energy that item is using.  Often people want to locate and shutdown devices in their homes zapping energy like a vampire by draining not only your precious energy but your wallet as well.  These outlet-based energy monitoring devices are great for very targeted and specific use cases, and they will remain as such well into the future.  Yet, these devices lack visibility into one’s greater energy usage.  It is like viewing a single tree in the forest instead of seeing the whole forest from above the canopy.

Have you ever dreamt of being able to instead have visibility into your house’s entire power consumption?  The ability to see individual high-load devices (per circuit) or even your main grid consumption including solar production?  While researching this for my own home, I looked initially at a few commercially available devices from a few different companies such as: Sense, CURB, and Neurio.  Most of these solutions monitor a limited number of power sources (usually grid mains and/or solar at an additional cost).  A few of these systems attempt to guess what a device is by looking at loads within your home’s total usage and picking out motors or heating elements.  You than have to map these discovered devices to what it actually is in your home.  Let me say, it sounds easier than it really is.  Some devices like refrigerators or dishwashers have both high-load motors, low energy computers and heating elements.  Many times, this becomes a guessing game for the end-user.  Although the formulas and machine learning are getting better, they are by no means perfect.  Many of these commercial devices also require a service where your data is uploaded for viewing via a webpage or application on your smartphone.  One often is not given the raw data but only processed information.  You are also at the whim of the business to stay afloat while also making sure they are not profiting by selling your data to the highest bidder.


I believed there had to be a better option and I found a few while looking through YouTube videos.  People were making their own individual energy monitoring devices that were similar to a homemade Kill-A-Watt or their solution only worked with low voltage systems (IoT).  While doing additional searching, I found a website dedicated to using both open source software and hardware focusing on energy monitoring and a few environmental monitors as well.  If you are at all interested in products like these, I highly recommend you have a look at their great website located CLICK HERE.

This site has a vast amount of resources and great forums where people regularly share and exchange different ways of monitoring one’s energy.  I was draw more and more to this site as a great way of researching my needs, and while doing so, I came across a neat product that if you were not already aware of, is one of the best energy monitoring tools for your home out there.  Yes, it is that good.  I have researched, purchased, and install my own system and it really was not that difficult for someone who is knowledgeable around high voltage.  I, and the maker of the device, recommend the system only be installed by a certified electrician.  This is the same advice other commercial products give for their systems as well.


image002So, without further ado, let me introduce you to the open source IoTaWatt energy monitoring hardware and software which can be found CLICK HERE and you can have a look at their very active and friendly community forums by looking CLICK HERE.  This unit when fully configured, including the device, power and reference adapters along with accessories is about $100 US less than the above mentioned commercially available systems.  And, one big benefit is the data collected by the device is yours to keep and do with as you wish.  What is even better is that the creator of the device has all the items necessary to get you up and running in no time when you visit his site.  All the equipment he sources and the IoTaWatt itself is CE rated and safe for use for energy monitoring within the US.

The setup and configuration are intuitive and simple.  If you have ever bought and connected a smart device (Alexa, smart plug, etc.) in your home, you can setup and configure an IoTaWatt.  What is really great is the product not only supports United States power systems, but it can also handle 240v systems along with three-phase installs as well.  Just about any type of power system around the globe can be accommodated by this monitoring smart little device.  I can say that once you have a view into your power usage or production, it is hard to be without it.  At the time of this review, only US customers are being sold directly by the creator via his ( website, but do not fret, you can get your UK, AUS, JP, etc. IoTaWatt unit with the right adaptors from the OpenEnergyMonitor shop/website.  Either place you get the product; the creator supports it and the units are internally the same as if you bought it directly.

Some pre-instillation planning is necessary based on your specific need(s) or use case(s).  This is where many commercial solutions make the task easier by only giving you two options (in most cases) monitor your mains or monitor both mains and solar.  Not much else, with a few exceptions.  On the other hand, it may seem more complicated to install an IoTaWatt because there are more options and configurations available.  Do you only want to monitor your main power consumption only?  Do you want solar production measured?  How about specific circuits or loads in your house such as a well pump, sub panel, or other system?  Well, the great thing is that you can do all of these, and more, using the IoTaWatt open source energy monitoring system.  You are not tired to a cloud contract, and you have full control over your data.  The product does not have to guess at what an appliance is or is not as you have configured the device and monitoring units on the circuits you want to monitor.  I cannot recommend the product enough due to its excellent support from the builder and a friendly community that backs and helps with questions.  If you have ever wanted to see your energy usage, this is the product.

Let me break out the remaining portion of this review by providing a section on IoTaWatt’s hardware, software, and even some third-party integration options.  That way, if you are more interested in the hardware, you can read that section.  If software is more your thing, feel free to scroll down that that section.  I understand it is quite a long review, but there is so much I felt was important in covering this device that I had to make it longer than many of my other reviews.


image003So, you might be asking, what really is the IoTaWatt and how does it monitor my home’s energy/power.  It is a small microcomputer in a rugged plastic case that receives data from small devices called current transformers (CTs). CTs easily clamp around a circuit you want to monitor and as energy passes thought a wire, it creates a magnetic field which the CT is able to detect and convert to a value read by the IoTaWatt.   If you want to learn more about what a CT is and how they work, have a look here at the Wiki page: CLICK HERE.  Such information is beyond the scope of this review and the reviewer.  Once you have a CT attached to the circuit you intend to monitor, you simply plug the other end in to the IoTaWatt using the CTs attached phono jack adapter.  You can see an example of what they look like to the right.

I wanted to note, for people wanting to source their own CTs from cheaper places like AliExpress.  You are not required to purchase CTs from the IoTaWatt builder.  But, I highly recommend you do for a few reasons listed below.  First, the IoTaWatt is pre-configured and calibrated for the CTs sold by the maker, if you buy other models you may need to do some tweaking to get things just right.  Secondly, the CTs purchased from the creator have 1.5m (5ft) of cable attached where many of the CTs sources from Asia only have 1m (3ft) of cable.  For me, the longer cable the better it allowed me options when I installed the unit.  Thirdly, the CTs sold by the maker are CE certified so they are approved to be used in US instillations.  Some of the cheaper CTs have no rating for safety, and for a few extra dollars you can rest assured that the certified ones will be safe and provide a reliable monitoring output.  If you are thinking about going with your own sourced CTs, I recommend you have a perusal through the IoTaWatt forum pages for other’s experiences and issues.


Disclaimer: For those who are unfamiliar with electricity or the image to the side looks intimidating, it is highly recommended you have a licensed professional assist in the planning and install of your IoTaWatt.  Again, this is nothing different from commercially available devices either.  As exciting as monitoring one’s energy is, your life is more important.  This review is not intended to be a primer on electricity however a few things are important to understand when looking at using or installing an IoTaWatt.

When planning your install, you will want to know the circuits you desire to monitor in addition to your mains (grid) power.  You are not required to monitor mains power, but this is really one of the main (no pun intended) reasons to monitor your home’s energy usage.  Of the fourteen available monitoring ports on the device, two will most often be used for monitoring two-phase (US) energy systems.  If you have a three-phase system, you would need to use three ports to monitor your mains.  From this point on, when I talk about power or the grid, I will be referring to the standard US 120v/240v two-phase system, but again this device can be used in many different system types.

In the US, homes have two power legs with each leg (or phase) delivering ~120v.  For devices requiring higher power needs like dryers, electric ranges or furnaces the type of circuits is usually a larger breaker in the electric panel spanning both of the 120v legs for image005a total of 240v.   So, you may want to begin by thinking of the devices you would like to monitor most and make sure the count does not exceed the total fourteen available ports; actually, twelve if two ports are taken up by the mains.  The last thing you will want to take note of is the amperage (current) rating of the circuits. My install consists of two 200-amp CTs for my mains as I have 200amp service to my house.  I also have a 100amp CT for a 100amp sub-panel circuit, and the rest of my monitored circuits have 50amp CTs attached to them.  There is no need to match the CT value to the circuit exactly, but the CT must be equal to or exceeds the total amps of the circuit being monitored.  Looking in one’s electrical panel you will find a number written on the breaker somewhere containing an amp rating such as; 20, 30, 50, 100, and 200 which are the most commonly seen in US home electrical systems.

Now that the above boring, yet important, electrical thoughts around planning an install out of the way, you will need to know the volts, amps, and number of circuits to ensure you purchase the correct number of CTs at the right amperage.  You can see an example like the one on the right.  It is rated at 200A (amps).  The example is one of the CT that was attached to one leg of my mains.  You can clearly see the CT is CE certified where many cheaper ones are not.

I will say that the forums once again were very important for me getting up to speed and recommendations, so I would advise you also lurk in there for a period of time.  The group is very friendly, and they do not bite; which is a good thing.  I was quite fascinated by learning of other electrical systems around the world simply by reading the posts, etc.  There are some very unique and different systems then those found in the US.

You will also want to make sure you have at least two available outlets near where you plan on installing the device. One is needed to power the IoTaWatt and the another is used for reference voltage; necessary in calculating watts.  Remember, you can always add more CTs to your install at a later date, so if budget is a concern, I recommend you monitor your main power usage (and solar if you have it) and work from there.  It is easy to do the install in stages, but I wanted to go all in and complete it in a single deployment.  Sometimes it is easier to have the panel open once or a professional come out only one time for a full install.

The IoTaWatt is lightweight and compact.  For US deployments, it is recommended, and in some states code, that the physical device not be placed in the electric panel along with high voltage.  I have seen and suggest one mount a box outside the panel in a dedicated protective box.  I purchased an 8”x8”x4” junction box from my local hardware chain store which protects the device using eight screws and as a bonus it is watertight.  A waterproof case is not a requirement for my install in a dry basement, but for some people who have panels outside it may be a good idea.  I have also seen many others use something called a NEMA box which is a bit more expensive, but they often have a door that swings open and some have latches where a small lock can be installed.  Because different states, cities, or towns may have their own codes relating to how one needs to separate high-voltage from low, I recommend you review or visit your permitting office for details.  I know I have continued to repeat myself here, but if you have any questions or concerns, make sure you have the unit installed by a licensed processional.


Figure 6: The IoTaWatt and all accessories

When I purchased my device from the designer, I received a well packaged and protected unit along with the necessary adapters (power/reference voltage), along with the pile of CTs I ordered.  You can tell that the device was well thought out as it is installed in a slim case and all the CT ports are well labeled.  A nice touch was that the device came with a custom mounting bracket if you want to professionally mount the unit where it can be easily removed.  Everything I received was well packaged, CTs were bagged by amperage rating, and the two power bricks were each in a box.  Once I had all my requirements worked out and vetted via the forums, I simply placed my order, payed with PayPal, and in a few days, all items showed up on my door step.  Things could not have been easier.  If you have ever placed an internet order or used PayPal, you can pick up one of these units effortlessly.

The following images show the pile of 50A, 100A, and 200A CTs I purchased for my install.  For those with a keen eye, I did put number labels on both ends of each CT to give me a better way of troubleshooting an issue.  I can easily know what CT goes where both in the panel and where it is connected to a circuit.  These number labels can be printed yourself or found where electrical supplies are sold.


Figure 7: A Pile of Current Transformers

The above image is the pile of all my current transformers used to monitor my home’s energy.  You can see that the cables come neatly wrapped with a wire tie and the one sold by the maker are well labeled and carry the CE certification as well.


Figure 8: 10A Current Transformer

The above image it my one and only 100A CT used to monitor my barn’s sub panel.  I am only monitoring one leg of the 240v circuit and doubling the reading in the device, so I can represent power flowing through both legs of the circuit.  It is harder to see from the image, but each of the CTs are about half the size of the next larger size.  So, a 200A CT is nearly twice the size of a 100A, and a 100A if about twice the size of a 50A.

Below is an image of my two mains 200A CTs.  I initially purchased them to monitor my two main power legs.  However, these two CTs were later replaced with a clamp style due to the space in my panel being tight and the mains cables were taut with little room to spare for the larger sized transformers.


Figure 9: 200A Current Transformers

For those interested, the below shows the device, the mounting bracket, and the two power adapters required to operate the IoTaWatt unit.  Again, it is a well-thought-out, clean, and a well-built piece of hardware.  By no means was it slapped together, and it is clear that the developer took the pain and effort to have the unit certified for US installs.  This is no small feat for those who have had a product go through UL or CE certification.  Kudos for the focus on safety and security for a device that will be connected (indirectly) to your home’s main power system.


Figure 10: IoTaWatt with Power Bricks and Bracket

For those interested, the image below is a close-up of the mounting bracket.  This bracket comes with the device, but you will need to open the unit up if you intend of using it.  Not that this is difficult, but something I needed to Google for the answer as I did not want to void any warranties cracking open the box myself.  Once I saw how easy it was to remove the four rubber feet and unscrew the cross-head screws found underneath, attaching the bracket to the device was trivial.  Make sure you do not have the device powered on or any CTs connected when you attach the mounting bracket; just to be safe.


Figure 11: IoTaWatt Mounting Bracket

The next few images show the IoTaWatt from various sides and angles.  I only included one of the sides showing the CT ports as both mirror each another in both look and functionality.  Also, take note of the well-designed layout and the sleek box the system comes in.  My only issue, which may be on my unit, was that the text for the product name was not centered as the logo was; maybe this is a design choice from the creator.


Figure 12: IotAWatt Top View as I mounted it

In the below image, you can see seven of the ports where the CTs plug in, this is only half of fourteen total available.  You can also see how the small rubber feet are pressed in and under there are the four screws that need to be removed if you wish to use the provided mounting bracket.


Figure 13: IotAWatt Side view (CT Ports)

The photo shown below is the bottom of the unit.  You can see a warning sign which is there intentionally to prevent people from opening the unit when it is operating.  Caution needs to be made when opening the device for any reason while any of the CTs are plugged in as there may be a high level of current flowing even when the box it unplugged from power.  Be aware that the CTs will create voltage and current as long as energy is flowing though the cable they are connected to, so the provided warning is not to be taken lightly.

In the middle you can clearly see the two small holes where the screws for the mounting bracket will attach to the back of the case.


Figure 14: IoTaWatt Bottom View

For those interested in seeing the device’s certifications, you can find them clearly listed on the bottom of the unit.  Here for US deployments, you can see the CE, UL, and FCC notifications.  Again, I have to give the builder of the IoTaWatt credit for going through the difficult process of certifying a bit of electronics that will be used for monitoring one’s energy usage.  Not only is it a great tool, it is a safe tool as well.


Figure 15: Certification Label Close-Up

Lastly, you can see the back side of the unit where both of the power transformers (5v/9v) are connected along with a small LED that allows the device lets you know if it is operating correctly or if it has any issues.  Again, note that this device requires at least two outlets near where you plan to install it for these two plugs.


Figure 16: Power & Reference Volts, and LED

The below image shows how the CTs attach to one’s power mains.  As stated previously, I later replaced the below CTs with clamp type connectors over the ones shown.  For those who know how CT are to be connected, I did properly install them after I took this picture.  You may be able to see the K -> L symbol, and in a US install, one should be facing the opposite direction from the other.  One of the great things that the designer of the IoTaWatt has provided is a way within the tool to see that a current transformer is improperly installed.


Figure 17: CT Attached to Mains (one backwards)

After installing the various CTs and running all the cables thought the small bit of conduit attached to the side of my electric panel, you can see what is close to the completion of my install.  All is neat and tidily secured behind the nine junction box screws.  As stated earlier, check with your local electrical codes and/or have a certified electrician do the install for you.  Once it is planned out, it really does not take much time to do the actual hookup in the panel.


Figure 18: Box Mounted and Conduit to Panel

When I remove the junction box cover, you can see that I have the IoTaWatt unit mounted using the provided bracket attached to the back of the plastic junction box.  This picture was taken prior to my solar install which I reserved ports #13 and #14 for.  In my install I only have one port remaining and I’m thinking about what I would like to monitor, or I may simply keep it as a floating CT which I can move around when necessary.


Figure 19: Junction Box Cover Removed

Ignoring my very dirty electrical panel cover (I later cleaned it), you can see a wider view of the install and how all the cables run between the device and power and also into the small electrical conduit for safety.  It should be noted that my electric box is not flush mounted like many current systems.  If your electric box is flush to wall, there may be more work required to have it properly installed.  Again, this is where a professional is needed to ensure it is done safely and to code.


Figure 20: Showing my dirty panel cover and IoTaWatt

The last two images show the box with a “Energy Monitoring Low Voltage” warning sticker and you can see where some of the CTs attached in my electrical panel.  They are the smaller black block looking items.  You can also see where I have the device’s power cable plugged in to the outlet below.


Figure 21: Showing my final install and label plus CTs on circuits

Lastly, the next image shows the box closed up with everything sealed and labeled ensuring everyone knows what it is.  Once configured, the device really is a “set it and forget it”, so sealing it away behind screws is not a bad thing.  For those who intend to change things around or would like a more professional looking install, I would again suggest you have a look at NEMA rated boxes with swinging doors.  I wanted to get things up and running quickly, so I did not wait for such an enclosure; but they look great.

Figure 22: Closed Up and Labeled


A piece of hardware is only as good as the software it runs.  The designer could have built the most robust and safe hardware but cripple it with bad coding.  This is not the case with the IoTaWatt.  The designer took painstaking effort to design a simple and intuitive User Interface (UI) that runs on a microcomputer having very limited resources.  This section is not a tutorial on the use of the tool, but I did want to touch on a few points so you can see that the software that runs the device was well-planned.

Like with setting up any new IoT device on your network, the IoTaWatt is no different.  You simply connect the CTs, attach the two power cables, and there is a short wait for the device to start up.  You can verify all is operational by the LED color or flashing sequence.  Once the unit is up and working, you will use a smart phone or computer that has Wi-Fi to attach to the newly broadcasted Wi-Fi network.  Be aware, this unit does require you have Wi-Fi as it does not have an ethernet jack; refer to the device’s images above if you want to confirm.

Once attached, you will be presented with the below image of what really is a small webserver running on the device’s microcomputer.


Figure 23: IoTaWatt Main Menu

Surprisingly, it is not a dumbed down configuration only interface.  Not at all.  As you can see below, each of the four main buttons have a set of sub menus with various settings.  Don’t let the number of options scare you away, most you do not have to touch if you do not want too.

If I press the “Setup” button, you can see there is a set of expanding options ranging from “Device” options to connecting the unit to third-party systems; covered later in this review.  There are many items which a user can adjust, yet most are not necessary.  This allows one device to be used for monitoring various power system configurations or setups.


Figure 24: IoTaWatt Setup Menu

Clicking on the “Inputs”, after first connecting the devices to your local wireless access point, here you can setup and label the inputs you are monitoring.  Below you can see the reference voltage, my two mains, and the various items I was interested in monitoring individually.  Most of these are high-loads or high-power consuming devices.  The items you monitor will vary based on your individual use case, etc.  You can clearly see at the bottom of the “Inputs” screen a check box to enable three-phase systems.

By clicking on the input’s number (it is a button) on the left of the screen, you can set the various options on the type of CTs and a few other things.  Here is where I again recommend you purchase the CTs available from the device’s maker because setting up inputs is straight forward and comes pre-configured and calibrated.  If you instead source the CTs from other places, you may need to do some fine-tuning to get the precision one can achieve with the ones sold by the designer.


Figure 25: IoTaWatt Inputs Menu

If you click on “Outputs” from the “Setup” menu, you are given the ability to do a bunch of calculator-like manipulation of inputs.  For example, you can see in the below Outputs I have created, my “Total Watt” usage from the grid is the sum of my two mains CTs.  My “Other” is a total of my two mains minus the devices I’m individually monitoring.  These are only the tip of the iceberg when speaking of configuration and Output options.


Figure 26: IoTaWatt Tools Menu

The tools menu gives the user access to the lower-level regions of the device.  Here you can edit or manage specific files, you can view message logs, and even do a remote restart of the system if you do not want to go to the panel and disconnect the power.  This menu is mostly used for troubleshooting and most using the device will not have to go in to it unless directed.


Figure 27: IoTaWatt Tools Menu

Clicking on the “Status” menu shows you in real-time the data from the Inputs and any configured Outputs.  The designer also includes data relating to Power Factor (PF) for devices being monitored.  On this same menu, you can see the device’s statistics such as the firmware being run, how long the device has been up and running (I recently had a power outage), along with a number of items relating to the health of the device.  Lastly, you can see if the unit is connected to a third-party system (covered later in this review) and some data log information, again mostly for troubleshooting only.

One of the really neat things is that the developer included an Over The Air (OTA) update system for people who want to live on the bleeding-edge. They can receive Alpha code update when they are released.  For those less inclined, they can receive minor updates, and for the really concerned, you can have your device auto update only to the most stable code.  Again, this really shows the time and effort in building this device.

I did want to note for those interested, the unit records all captured log data to the provided SD card which comes pre-installed along with the device’s operating system.  So, even if the power fails, it will retain all the data the device collected up to that point.  When things get going again, it will pick-up where it left off and even batch upload data to a third-party system if necessary.


Figure 28: IoTaWatt Status Menu

One of the last areas to cover from the main menu is the “Graphs” option.  If you are like me, this is where you will spend much of your time looking, unless you export the data to a third-party system.  Graphing or charting is functional and overall feature rich.  You do have to remember these graphs are being generated on a platform with limited memory and CPU power, so you cannot expect them to be as quick or rich one can expect from a desktop doing the same thing.

The graphing UI is well-thought out and one can tell the code was shared between a third-party solution as they have the same look and feel.  Charts and plotting are as simple as selecting the item(s) you want to graph (mains in the example below) and the data appears.  You do have the ability to change the data set by clicking on the items near the top.  You can view data by day, week, month, year, or any sub-set thereof.  Drilling down, or zooming, into the data by simply clicking on the “+” or using the “-“.  It really is that simple.  I also liked some of the additional data provided at the bottom of the chart which includes MIN, MAX, ADV, etc.  Great for people to see the power of a system like the IoTaWatt and knowing this is all done on a microcomputer is even more impressive.


Figure 29: IoTaWatt Graphing Example


Figure 30: Additional Details Graph Data

One of the last things I wanted to point out was that you can save and retrieve your graphs for later retrieval if you would like by providing the name and pressing “Save”.


Figure 31: Graph Save Option

As I said earlier, a piece of hardware is only as good as the code it runs, and I can say that the developer/designer of the IoTaWatt did an exceptional job with the limited resources to provide a feature rich experience from a little case.

Third-Party Integration:

The last bit I wanted to touch on was how the IoTaWatt integrates with third-party systems.  The product is designed to interconnect with the open source EmonCMS tool provided and supported by the OpenEnergyMonitor organization.  EmonCMS can be self-deployed locally on lower-end hardware like a Raspberry Pi or even hosted in a hosting provider like Amazon’s AWS or Microsoft’s Azure.  The OpenEnergyMonitor organization also provides EmonCMS as a service if you desire to leverage their solution.  Go have a look at their offering if this interests you.

Below is an image of my EmonCMS dashboard running locally on a Pi computer.  Third-party integration allows one to easily build out visual systems around dials, charts, and more.  As seen in the image below, I have not only my data from the IoTaWatt energy monitoring tool flowing into EmonCMS, but I also have a number of weather-related data points including temperature, humidity, wind speed and direction, along with lightning and solar radiation data.  One can easily generate these dashboards form the data IoTaWatt gathers.

Integration into an EmonCMS is as easy as providing the IoTaWatt device with the IP address and API keys generated by the system once installed and nothing else.  Once the data is added to IoTaWatt, the data collected is sent about every five seconds to the system for long-term storage.

If for any reason the IoTaWatt is unable to upload data to the EmonCMS system you have it pointed at, the device is smart enough to store and batch upload any data once the EmonCMS system is operational again.  It is the subtle things which the developer has added to the systems that makes it both flexible and easy to use.


Figure 32: EmonCMS Dashboard Example

The below image is simply showing the gauges I have on my dashboard representing various energy related monitoring points.  The gauges I have used below also have a max or peak usage meter that resets daily.  The red numbers and needles show this MAX usage value.  I also have a chart that shows my energy usage for not only the week, but the previous two weeks as well.  This allows one to review briefly see their long-term power usage over weeks.


Figure 33: Energy Gauges in EmonCMS

Like with the ability to modify or combine the various input number you wish to store or collect, you can do a similar thing within EmonCMS.  The below image shows a few ways you can combine or manipulate the inputs to meet your needs.


Figure 34: EmonCMS Input to Feed Example

Lastly, the EmonCMS tool has what are called Apps that take various inputs based on the App and perform a lot of computation to present the data in a very visual way.  In the below two examples, you can not only see the daily usage, but you also have the ability to easily see your data in a different format by clicking on the buttons similar to the Graph view.


Figure 35: EmonCMS Charting Example

Here you can see the amount of energy used on a daily basis along with weekly, monthly, and yearly averages.


Figure 36: EmonCMS Trend Chart


I have looked at other energy monitoring tools and technologies and I have yet to find one that is as simple, comprehensive and well supported as the IoTaWatt device.  It is clear that a lot of thought and planning went in to both the hardware design and software implementation.  Once the unit is setup, it can be left to its own to collect the data you would like to gather.  What I have seen other people do is deploy an IoTaWatt to other family members homes and monitor them all via a single EmonCMS setup.  Unlike many of the other solutions I’ve looked at, this one comes with fourteen inputs where most of the commercial ones have two or four to simply monitor mains and/or solar.  The device is smart enough to log all its data to the provided SD card and also integrates very well with third-party products like EmonCMS.  I do not think you can go wrong picking up an IoTaWatt if you have any desire to monitor your energy usage.

Just because something is said to be Open Source does not mean it has not been well designed and implemented.  If you are an adventurous type, you can pull down the project schematics and software from Github and build one from scratch.  Knowing my soldering skills and patients, I though it best for me to purchase a fully assembled unit.  I have seen other that have gone the built-it-themselves route and they are not bad.  I really like my IoTaWatt and if energy monitoring is on your mind, I suggest you have a look at this before going with a commercial product.

Note: Often professional reviewers are provided items for free in exchange for an honest review.  I purchased the IoTaWatt unit and all the accessories with my own money to allow me the ability to monitor my own home energy usage using the best tool available on the market today.

10 thoughts on “IoTaWatt Energy Monitoring Device Review

    1. Sure can. Generation (solar) and Consumption (grid) can be measured. I also measure my home battery using this tool. Including well pump, AC, two sub-panels, etc.


    1. Based on where you live and shipping, the price can very. I’m in the US and for the unit and 14 CTs for measuring different circuits, it was in the $325 range. I did add-on a few of the more expensive clamp CTs for my mains as they are rather limited in space and tight.


  1. Does it only measure per breaker CT or can it be programmed to measure multiple devices on one breaker CT (similar in concept to what the Sense system is supposed to do, but apparently doesn’t work fully)?


    1. This is a per-breaker monitor, it does not attempt to leverage any “machine learning” like the Sense; which often fails at this role because it is hard. People often find that they want everything to be monitored, but what is most important is more your total consumption and large load devices (dryer, range, AC, well, spa, etc.) The other items in your panel are often such a small delta. The tool does allow you to exclude known feeds to extract the “remaining” misc. power usage such as outlets, or non-monitored items. So, it really gives you a great view and flexible. Thank for the question.


  2. I own two of these. One for each panel in my house. I cannot agree more with the authors review of this device. If I had any complaints, it would be that it only has 14 ports. I’m able to monitor all of the important stuff for sure but by the time I get a CT on the dryer, the furnace, the well pump, two sump pumps, freezer… Etc, I’m out of ports. I swap them around from time to time to watch different things but I’d gladly buy more CT’s if it had room. Definitely not a deal breaker but I like to monitor as much as possible. I’ve had both of mine up and running for two years and they’ve paid for themselves in energy savings and “awareness factor”. By awareness factor, I mean that I was able to spot a leaky toilet by noticing the well pump cycling way too much. I was able to catch a faulty sewage pump by noticing it didn’t run at the same time a shower was being taken. I was able to spot an issue with a weak garage door spring by noticing a slow increase in the amount of power the garage door opener was using each time it operated. I was able to tell the loads on each leg going to one my panels weren’t very well balanced. A little rearranging of circuits in the panel and now the legs are much closer. I’m using emoncms and can check the feeds in real time from my phone anywhere I have internet. Nice when you’re at work or on vacation. I tell everyone I know about this device and highly recommend it to all. In two years time, I’ve managed to reduce my electrical consumption by about 35%. I’ve made some investments this year in high efficiency energy star equipment that will hopefully reduce my energy consumption to half what I was using before buying these. My ultimate goal is to invest in solar but wanted to take steps to reduce my usage first. The first phase of my plan was to figure out how we used energy in the home and this device is ideal. The power of long term data analysis is extremely useful. Owning all the collected data is a must. It would be nice if this unit had the ability to incorporate a temperature probe but that can be done thru emoncms. You can create a trend showing outside air temp compared to furnace or AC runs over an entire season or years. The possibilities are almost limitless when it comes to analyzing the data. It would also be nice if both of my units could talk to each other and share data. Emoncms allows this but it would be nice if it was native to the units. I’m in no way affiliated with iotawatt. I’m just an extremely pleased energy nerd. None of my complaints are anywhere near deal breakers. I think devices like this should be standard equipment on a home.


    1. JC great details and I continue to love the product. It just works and no required interaction. I like the integrations the creator has provided out of the box along with the continued development using newer chips, etc. I can also say that he is working on a way to chain multiple units together to get more ports. It is coming, just takes time and certifications.


  3. Thanks for the very informative review – it’s much appreciated. I would, however, like to point out an error in your nomenclature of power systems. You described US 120/240 power as being two phase, which it isn’t. It’s actually single phase (aka split phase). Two phase power is all but extinct in the US now.


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