Battle of Electric Monitors


#1

When my house was built 1.5 years ago, I had a critical load panel installed and this had a Generac associated with it for when there is a loss of power. The folks that installed this also installed a efegy Elite energy monitor. This is just connected to the mains that feed into the sub panel.

Recently, I picked up a Sense unit and connected this to the Mains that go into my main panel that also feeds my sub panel. Logic would say that the feed into the main panel should read higher than the sub panel. Also, when I look at Sense and my meter outaide, they are very close in readings.

You guessed it, the efegy unit consistently reads higher then the total usage of Sense.

Just seemed like something odd is happening.


#2

Hey @jasonemoyer - thanks for posting this!

It looks like the Efergy is displaying a calculation of kWh, is that correct? Presumably gathering power data for the last hour of power consumption? In Sense’s “Now” screen (the one with the bubbles), you’re seeing the real-time display of power in Watts (updated every few seconds) instead of kWh. However, if you navigate to the Trends screen, you could select the daytime view and tap on the past hour to view usage in kWh. That would probably be closest to the display that the Efergy is using.

Some other reasons for a discrepancy could be:

  1. Difference in sample rates: I believe the Efergy is measuring power once every 10 seconds. Sense would be measuring power quite a bit more frequently.
  2. Calculation of power: As the Efergy transmitter is battery powered, it’s likely their power calculation assumes 120v instead of measuring instantaneous voltage in addition to current, whereas Sense is measuring both current and voltage at 1 MHz, and calculating power (in watts) from there.

Would any of that help explain the difference? Keep us up to date on your findings. We love head-to-head tests to keep us on our toes!


#3

My sense appears to be more accurate than my solar grid tie inverter in terms of usage and power actually generated back into the grid. I live in Mexico where after 500 kwhrs per two month period your electric bill quadruples, and, you have to stay below the 500 ceiling for a year for it to drop down to the base rate. I have 4200 watts of solar and my electric is completely free. I bought the sense monitor because I added a mini split heat/cool unit to my living room and wanted real time monitoring of where I am at in regards to generation and usage. The sense monitor is exactly what I needed. Good gear. m.