Difference between inverter kWh output # and meter output #?

HX_Guy

Is this pretty typical or something that needs to be looked into?

Now that I have an actual meter from the POCO, I can check it against my inverter and again the TED5000 (which has always shows a little less than the inverter). Well, the meter itself actually shows lower than the inverter as well.

SolarEdge Inverter: 53.38kWh
POCO Meter: 51kWh
TED5000: 51.5kWh

I thought maybe the inverter is showing DC kWh and not AC, but they are too close, if that was the case the difference between them would be bigger.

BB.

In general, if your measurements are within ~5%, you are doing pretty well. If they are all within 2%--That is probably about as accurate as you can expect.

Here is an interesting white paper on Utility meter accuracy:

http://www.cpsenergy.com/files/Smart_Grid/smart_meters_epri1.pdf

-Bill

HX_Guy

The meter actually seems to be very accurate, at least backed up by the TED5000 device. It's the inverter that I'm not sure what it's going and why it's showing higher than both.

Basically my concern is...is there something going on that could be fixed so that 53kWh that the inverter shows makes it to the meter? Or the invert is just inaccuarte?

BB.

Do you know what the line voltage is at the meter vs the Inverter(s) and solar current is?

For example, if you have 240 VAC at the meter and 250 VAC at the inverter output--That would give you a ~4% line/power loss.

-Bill

HX_Guy

The SolarEdge inverter is reporting an AC voltage of 245.16V while the TED5000, which is inside the main service panel, is showing 121.3V (242.6?). So that's about a 1.1% loss? The run is only about 15 ft, is that normal?

I can take a multimeter to it later and check actual voltages, but that's what I was able to gather quickly.

BB.

What is the current and the wire gauge?

Each meter can be easily be off by 0.6% -- So, 1.1% difference is not impossible to explain by meter accuracy.

-Bill

HX_Guy

47.5A (max) and 6AWG wire.

BB.

http://www.calculator.net/voltage-drop-calculator.html

47.5 amps * 6 AWG * 15 feet @ 240 VAC

Voltage drop: 0.56
Voltage drop percentage: 0.23%
Voltage at the end: 239.44

-Bill

solar_dave

You are in the realm of noise within the measurements. Mine is much the same, I think the inverters are slightly optimistic. BTW the TED has a multiplier to adjust variability the CT/MTU.