Problem exporting hourly data

[unilhexio]

Hi!

I have detected the following possible bug: when exporting to a file the Energy injected into Grid (hourly data) I obtain these values (for example):

30/11/1990 4:00 0

30/11/1990 5:00 0

30/11/1990 6:00 0

30/11/1990 7:00 137965

30/11/1990 8:00 441761

30/11/1990 9:00 683361

30/11/1990 10:00 866946

30/11/1990 11:00 1131088

30/11/1990 12:00 824554

30/11/1990 13:00 444963

30/11/1990 14:00 364957

30/11/1990 15:00 430901

30/11/1990 16:00 135101

30/11/1990 17:00 -3247.8102

30/11/1990 18:00 0

30/11/1990 19:00 0

30/11/1990 20:00 0

namely, there are values below zero although "night disconnect" is marked in external transformer detailed losses (ohmic losses). This occurs randomly and always in the beginning and final hours of a day. I have realized this problem at least from version 5.57.

Moreover, the total sum of Energy Injected into Grid including negative values, is employed in order to calculate the performance ratio and the specific production of the PV Plant.

Is this a real Bug or am I doing something wrongly?

Kind regards.

[André Mermoud]

This negative value is rather low (around 0.3% of Pmax)

The simulation is performed on a complete hour, and therefore also the "Night disconnect" function.

Now in for one hour the PV production doesn't compensate the iron loss of your transformer, you can have a negative balance over the whole hour.

[unilhexio]

Thanks for you reply, André.

[Mike_R]

I have a similar issue (energy injected into the grid) except for every off hour that should be outputting zero, it outputs -1128. The output looks like this:

Year Hour Output

90 0:00 -1128.1739

90 1:00 -1128.1739

90 2:00 -1128.1739

90 3:00 -1128.1739

90 4:00 -1128.1739

90 5:00 -1128.1739

90 6:00 -1128.1739

90 7:00 -1128.1739

90 8:00 72829

90 9:00 165092

90 10:00 258385

90 11:00 330807

90 12:00 311933

90 13:00 209167

90 14:00 133950

90 15:00 54034

[André Mermoud]

You have defined Transformer losses.

When connected to the grid, the transformer consumes some energy (iron losses), explaining this night negative energy.

You have the opportunity of disconnecting the transfo during the periods when the inverter is OFF (in the rreality, this means a HV automatic switch on the grid).