After the climate change-fueled wildfire season of 2017 gobbled up our home, we rebuilt our home the right way, with rooftop solar, energy storage, and no fossil fuels piped to the house. For our new fully electric home, I was eager to understand what appliances were energy hogs and by how much. Having just talked with Sense CEO Mike Phillips about their solution, a review was the obvious next step and it was right on time.
The Sense home energy monitoring system is a bolt-in system that leverages powerful signal analysis and disaggregation tech to discern which devices in the home are running in realtime. Each electrical device in the home has a unique usage profile that, thanks to Sense’s advanced signal processing chops, can be seen amidst the noise of all the other devices using electricity in the home.
Disclaimer: Sense provided the sense unit free of charge for the purposes of this review. The author paid all installation costs.
After it is installed, Sense monitors the home electrical system, and over time, it identifies unique devices that help homeowners understand what the big energy hogs in their home are. It is an extremely powerful tool for building a plan to improve the energy efficiency of a home. For a deep dive into everything Sense does, check out our interview with CEO Mike Phillips from November.
Recently, Sense added the Sense Solar system to give owners with a rooftop solar system more visibility into how the home’s electricity consumption and solar are working together. The Sense Solar system adds a second set of monitoring cables to the system to provide more granular tracking of the energy production of the on site solar system.
The hardware to pull in energy signals is comprised of a set of CT (current transformer) clamps that simply clip around the leads powering the primary electrical panel for the home like a set of tiny plastic handcuffs. These clamps are able to read power flowing through the wires without actually penetrating the wire, which feels a bit like the future. A second set of CTs was added to the solar sub panel to monitor all of the power flowing from the solar system and battery into the home.
Sense should be installed by a licensed electrician, as it requires a new circuit breaker to be added to the panel, among other, more mundane tasks. Two wires are connected from the new circuit breaker to the Sense unit to provide power to the unit. The CT clamps for the home electrical system simply need to be clipped around the main feeds into the home electrical panel, ensuring the arrows on the clamps are facing the same way.
Our installation was a tad more complicated, as our solar was run through a separate sub-panel, but it still only took a few minutes to fish the CT cables through the conduit connecting the renewable loads panel to our primary electrical panel. An optional antenna comes with the Sense unit that can be popped through a knockout on the side of the electrical panel for a better connection to the home’s WiFi network. Check out the official Sense install video for a visual walkthrough of the installation process.
Now that the hardware side of the installation was complete, it was time to get the system connected to the Sense app. I installed the app from the Google Play store (also available on Apple App Store). A few clicks later and I had an account set up. The device walks through a brief connection process to connect to the local device and it’s off to the races.
When everything is connected, Sense begins monitoring and analyzing the signals coming in from the CT clamps. All of the data coming into the system is fed through these two sets of sensors, and that’s where the magic starts. At its core, the Sense unit is an advanced signal analysis engine. It looks at the nuances of the power being consumed by the home and is able to disaggregate it into individual devices consuming power in the home. Sense did a great job of unpacking what the device does in just a few short minutes here:
It’s similar to fingerprints in that each device in the home uses power a certain way, and Sense knows how to sort through the mess to identify unique devices in the home. We learned that the pump in our new hot tub kicks on every 30 minutes throughout the day to keep the water warm. Sense identified the hot tub as a unique device, even suggesting that it might be a water heater or water pump.
We were then able to confirm what the device was, including the make and model of the unit. Doing this not only helps us track the usage of our hot tub over time, including the actual cost to operate it, but it also gives Sense another data point to help identify similar devices in other homes in the future.
The longer Sense runs on your home energy network, the more devices it will detect. Devices are initially identified by Sense as generic devices with a guess at what they might be based on what Sense has seen in the past. In our fully electric home, Sense identified a number of items classified generically as “Heat” devices. Sense shares its guess at what the device is, with that guess based on what other users have called similar devices.
To hone in on a specific device, I’ve found it helpful to wander the house with intention, turning on all of the devices in the house in order to see if any correlate with the new devices identified by Sense. If the specific device is identified, you can lock in the name of the device, and then add manufacturer and model information. This helps homeowners identify exactly what devices are running at any given time, as well as trending power consumption over time. If the refrigerator is running 24/7 and using $200 of electricity per month, it might be worth cleaning the coils on the condenser and checking the seals, or maybe it’s time for a new unit.
If the specific device can’t be identified at the time, it probably isn’t a big energy consumer in the first place, or it can be something that’s just used infrequently, like a clothes iron or blender. Because Sense looks at energy signals vs some sort of consolidated device ID, the devices it identifies can even be sub-components of a single unit. For example, it identified each burner of our stove as different devices. It’s impressive granularity, but makes the list of devices longer than makes sense at times. In our house, we saw that we used the front two burners more than the rear ones. That’s not a big surprise, but it’s fun to see it play out in the data in Sense.
After a few devices have been identified, Sense is able to make more sense of the big globs of energy consumption. These are parsed out in the “Now” tab of the app in a bubble cluster visualization. Each device gets its own bubble. It’s a great dashboard to see what’s happening at any given moment.
Identified devices show up as their own bubble, as does solar/storage. Unidentified devices are bundled together into the “other” category, and we get our first glimpse at the “Always On” category. This bubble is comprised of devices Sense sees running all the time, or nearly all the time. It’s things like the passive draw of a TV in standby mode, thermostats, alarm clocks, and the like. I would love a bit more visibility into what’s actually in there, but that will presumably improve over time as Sense continues to add more devices and more granularity to its analytical capabilities.
Below the bubble cluster, Sense lists the recent devices that have popped up in a chronological list. This is a great way to see when new devices were last used to correlate them to actual events in the house. In the screenshot, the pantry light is something I tentatively identified as a device in the app, but with the caveat that I wasn’t totally certain that’s what the device was, hence the question mark next to it.
Zooming out from the realtime tracker, the “Trends” tab in the app is home to a range of daily, weekly, and monthly trends and charts. These are helpful in identifying broader trends impacting the consumption of power in the home. With the solar add-on, we also have visibility of our solar production compared to our consumption.
I work from home and my wife does not, so our EV charging causes a bit of a duck curve in our daily electricity flow. As our Tesla EV charger, Solarglass Roof, and Powerwall do not leverage any intelligence to allow us to charge our cars only with solar, we use the data from Sense to optimize our charging patterns. After some tweaking, I used the data from Sense to set our charger to 16 amps to prevent it from pulling power from the grid at higher loads.
Our electric clothes dryer and water heater also cause large spikes that are clearly visible in Sense. We don’t have anything actionable to do about these yet, but I’m hopeful that SolarEdge’s intelligent water heating, inverters, and EV chargers will help solve this in the near future, though we don’t have plans to upgrade all of our home hardware just yet.
The app lets owners enter the actual price of electricity, to give the numbers a bit more context. We’ve waited months, but with our new electric service, permission to operate for our new solar roof, and the switch to and from a new clean energy collective, we still don’t know what the price of power will be for us. On the other hand, we produce most of our own power, so it’s not especially important for us.
In a fully electric home, heating and cooling are two of the biggest power hogs, and we see those clearly in the Sense app. In a 21st century fully electric home with two electric cars, however, the garage becomes one of the massive energy consumers, as electric vehicles consume around 10kWh/day for a 30 mile commute. Add two of those to the mix and the ~11kWh consumed by the average home in America pales in comparison.
Because of this, I was expecting Sense to pick up on the EV chargers as two of the key devices consuming energy in our home, but we simply didn’t. Looking over the charts, we could see the massive spike in consumption, but Sense did not identify them as EV chargers.
I talked with the Sense team about this and they shared that when it comes to looking at the digital fingerprints of an EV charger in the electricity consumption signal, it’s extremely hard because there are so many variables that impact how the EV charges.
- Is the battery hot or cold when the EV starts charging? If the battery is cold, the car will likely want to warm the battery before ramping charging up.
- What is the state of charge? Electric vehicles use different charging profiles depending on the state of charge.
- What is the charging speed of the EVSE the vehicle is plugged into? Charging a Tesla Model 3 on a 16kW/30kW/50kW charger will have completely different charging profiles.
- What version of the software is the EV running? Sense’s engineers told me they have to update the way they look for an EV in the energy mix depending on which firmware the vehicle is running, as manufacturers continue to optimize charging profiles as they learn more about how to optimize EV charging performance.
These are just a few of the factors that impact the digital fingerprints of an EV charging session. Sense is exploring ways to use EVSE software interfaces to communicate with chargers directly as an aide in identifying EV charging on a home network, but consistently identifying EV charging is extremely difficult using their more advanced signal analytics.
It makes sense when you think about it. A blender is going to work the same way every time the switch is flipped on. My hot tub will kick on the same way every time a heating cycle starts, and my laptop is going to sip power the same way every time I turn it on. EVs are impacted by a much wider range of variables that make identifying them based on their charging profiles much more challenging.
Sense is an indispensable tool for homeowners looking to better understand the energy being consumed in the home. For homeowners with solar, the Sense app provides an unparalleled look at the granular details of energy consumption in the home. In older homes, the Sense app could be helpful in troubleshooting high energy usage caused by an aging refrigerator or HVAC unit, for example.
As more and more homes around the world transition to fully electric operations, understanding what is happening with those electric appliances throughout the home will bring increased value to homeowners.
What has me excited about Sense is that while it is already extremely capable, they are only starting to scratch the surface when it comes to integrating the solution into the renewable home of the future. If the app knows I typically charge my EV for 3 hours per day, could Sense eventually start managing the different appliances in my home to optimize our self-consumption? It seems plausible and has me even more excited not only about fully electric homes, but about a renewable future for the world.