Reading Consumption Data from a Smart Electric Meter

Back in 2011 I enrolled in the NSTAR Smart Energy Pilot, a Smart Grid Program offered by my electricity provider. I was given a set of Tendril Home Area Network Equipment that included an Insight wireless display and a web portal on which I could monitor my electricity consumption on a minute by minute basis. I found this quite useful in getting me to change my behavior on how and when I used power. Unfortunately NSTAR decided to end the program in 2014 and disabled the hardware.

https://www.greentechmedia.com/articles/read/massachusetts-mulls-smart-meter-pilots-5987#gs.3vSg7JE

https://www.osti.gov/scitech/servlets/purl/1210191

In 2017 I decided to install rooftop solar panels and a NET meter. While the PV array can be monitored via a web portal to get hourly production data, Eversource (formerly NSTAR), only provides consumption readings once a month as part of their billing process.

Would it be possible for me to get data directly from my NET meter in the same way that the Tendril equipment did? 

YES!

I found this old article on HackADay:

https://hackaday.com/2014/02/25/using-sdr-to-read-your-smart-meter

which then linked to an active project using low cost hardware and open source software:

http://bemasher.net/rtlamr

Unfortunately most of the hardware recommended in 2014 was no longer available; however, in reading through the extensive comments on bemasher's website led me to believe that as long as I had an rtl-sdr USB dongle that used the RTL2832U and R820T chipset, it would work.

[ a clarification from bemasher: Any rtl-sdr compatible radio will work, not just the R820T tuner. See http://osmocom.org/projects/sdr/wiki/rtl-sdr#Supported-Hardware ] 

I ordered a $24 NooElec NESDR Nano 2+ from Amazon; my decision was based primarily on the smaller form factor, lower phase noise, 2 year warranty, and that it was spec'd for 24/7 operation:

https://www.amazon.com/dp/B01B4L48QU

The hardware in the dongle was originally designed by RealTek for use as a digital TV tuner that could be connected to a computer, turning it into a Media Center PC. Hackers quickly discovered that the drivers could be modified to turn the device into a Software Defined Radio (SDR):  

http://www.rtlsdr.com

As an SDR, the device can be programmed to scan across a range of frequencies. Once a signal is acquired, it can be demodulated and decoded as shown below:

http://bemasher.net/rtlamr/signal.html

Once the hardware arrived, I decided it would be easiest to use my Windows laptop to do a Proof of Concept before continuing onto my goal of running the code under Linux on a dedicated Raspberry Pi. The following steps were taken:

• Download and install the SDR drivers for Windows from NooElec. When installing the driver, in the drop down box choose Bulk-In, Interface (Interface 0). This may also sometimes show up as something prefixed with “RTL28328U”. That choice is also valid.

http://www.nooelec.com/store/qs

• Download and install the pre-compiled Windows binaries for rtl_tcp (an I/Q spectrum server for RTL2832 based DVB-T receivers)

http://sdr.osmocom.org/trac/attachment/wiki/rtl-sdr/RelWithDebInfo.zip

• Install git source control

https://git-scm.com/downloads

• Install the go build environment

https://golang.org/

• Download and build bemasher's rtlamr (an RTL-SDR based Automatic Meter Reader (AMR) decoder:

https://github.com/bemasher/rtlamr

go get github.com/bemasher/rtlamr

• From a Windows Command Prompt terminal, start rtl_tcp 
• From a separate Windows Command Prompt terminal, start rtlamr

When I first started rtlamr, I got a deluge of screen prints as I picked up every smart meter in the neighborhood. Fortunately, the tool supports various options to filter the data collection.

First I needed to limit my sample time:

-duration=0s: time to run for, 0 for infinite, ex. 1h5m10s

and then screen out repetitive messages (some meters were sending the same data every 5 seconds):

-unique=false: suppress duplicate messages from each meter

Next, I wanted to look for just my meter:

-filterid=: display only messages matching an id in a comma-separated list of ids.

However, I found that while I could detect and filter my neighbor's Itron C1SR meter using its eight digit Endpoint ID, I could not see my own Itron C4SR NET meter that has a 10 digit ID. It turns out that his older meter was using scm messaging, while mine uses scm+:

  -msgtype=scm: message type to receive: scm, scm+, idm, r900 and r900bcd

With the proper filters in place, I can now see that my meter is reading 99943.64 kWh:

 [click image to enlarge; id's are masked in the screenshots]




Next steps:

• Move the hardware and software to the Raspberry Pi
• Set up a database to collect consumption data on an hourly basis
• Merge in the Solar Array generation data
• Present combined generation and consumption data on a single web portal