SMA Home Manager 2 numbers don't much the main utility meter numbers

[terkazarian]

Hello

I've got Home manager 2 and SMA Tripower 15kw inverter.
The system configured to not export the extra power to the grid, it's only for self consumption.
The problem is that when I compare the numbers with the utility meter, there is something wrong.

For example, I've wrote down the reading in the morning when the solar power supplied all the energy needs of the house and then after few hours of 100% solar use I've checked the meter again and it shows that I've used about 6KWH while according to the Home Manager 2 during those hours it only used solar power (screen shot attached)

What could be the problem?

Thanks
Arthur

 

[BentleyJ]

Not sure when in the morning you wrote down the utility meter values but there is some grid consumption (gray area) between 8 am and a little after 10 am. The only way to know for sure is to measure current flow at various times of the day on the wires connected to the main breaker with a clamp meter.
It's possible there is some "leakage" of PV generation back to the grid. If this is happening the utility meter is probably not programmed as a bi-directional device and you may getting charged for any power being sent to the grid.

Testing is the key and it doesn't have to be an expensive Fluke meter or the like. You can get an Emporia Vue 2 with 2 CT's for $85 and it can be set up for Net Metering with 1 second streaming data.

 

[terkazarian]

Not sure when in the morning you wrote down the utility meter values but there is some grid consumption (gray area) between 8 am and a little after 10 am. The only way to know for sure is to measure current flow at various times of the day on the wires connected to the main breaker with a clamp meter.
It's possible there is some "leakage" of PV generation back to the grid. If this is happening the utility meter is probably not programmed as a bi-directional device and you may getting charged for any power being sent to the grid.

Testing is the key and it doesn't have to be an expensive Fluke meter or the like. You can get an Emporia Vue 2 with 2 CT's for $85 and it can be set up for Net Metering with 1 second streaming data.

Thanks for the quick reply.
the testing hours was from about 09:30 am to about 12:30 pm, it's very clear that there was almost no consumption form the grid, nothing close to 6KWH.
About the generation back to the grid, there is only a little amount of power that is going back to the grid (0.1KWH) until the inverter dropping down the power.