Total kWh off


#1

I compared Sense KWh used to my actual meter for April so far and Sense is over by 6%. (70 kWh). Is this normal?


#2

It is normal based upon’s people’s experience here. 3% to 5% seems to be the norm. Whether it can be corrected for on an individual system by a correction factor (may not be a linear relationship) or by Sense is a posed question that has not been answered.


#3

I’ve only had my Rainforest Automation Eagle (reads my metered readings online) for a month an a half, but I have seen quite good correlation at both the daily and monthly level. For the only full month, March, I have to compare, here are the results:

  • Sense - 1658 (usage) - 513 (solar production) = 1145kWh (net usage)
  • Rainforest Automation Eagle (via electric meter) = 1144.53kWh

Not bad for CT clamps !


#4

@marcbh, your readings should be within 1-2%. If you’re seeing a 6% discrepancy, I would recommend reaching out to support: https://help.sense.com/hc/en-us/requests/new.

@miracj, if a monitor is experiencing a large discrepancy, we’d need to look into that specific monitor more. The only known issue causing reading discrepancies is with solar calibration. That is something engineering is working on getting resolved in the next couple weeks.


#5

:confused:


#6

@BenAtSense [quote=“BenAtSense, post:4, topic:738”]
your readings should be within 1-2%. If you’re seeing a 6% discrepancy, I would recommend reaching out to support: https://help.sense.com/hc/en-us/requests/new.

@miracj, if a monitor is experiencing a large discrepancy, we’d need to look into that specific monitor more. The only known issue causing reading discrepancies is with solar calibration. That is something engineering is working on getting resolved in the next couple weeks.
[/quote]

Well looking at my Solar-Log production meter (accuracy 0.2%), the maximum peak production for 04/23/2017 was 10.25 kWh at 12:45pm as seen below

versus Sense measuring 9.974 kWh solar production at the same time

Thus calculating 9.974/10.25 => 2.7% low reading of Solar production by Sense (along with a daytime dip as solar production goes up), which is a bit larger than the 1 to 2% you referenced.

As I suggested in another thread, if the app allowed us to give our production and consumption meter values at various points, this would allow Sense to compute compensating adjustments using the values between value points to bring Sense closer to reality of the more accurate meters.


#7

I know, Nicholas. Sorry about that!! It is unfortunately taking longer than expected.

@miracj, understood! When I said 1 to 2%, I was referring to Sense without solar as I know we have a known solar calibration error affecting some.


#8

Hi miracj, all,

I’m going to restate my numbers to include the March readout from SolarCity’s SolarGuide, which is based on the wattage read at the inverter. Given my numbers, plus what I’m hearing from others, it looks like there are losses through the inverter and into the main breaker box. Given that Sense number for the month lines up so closely with my PG&E meter number, I believe that my SolarCity fails to take into account inverter efficiency loss which can run up to 4% plus perhaps some additional ohmic losses. I’m seeing a differential between the two of around 5.1%

See page 9-10 of:

Sense - 1658kWh (usage) - 513kWh (solar production) = 1145kWh (net usage)
SolarCity (solar production at inverter) = 540.7kWh
Rainforest Automation Eagle (via electric meter) = 1144.53kWh