What is the meaning of colors on electricity meter balance chart?

[klew]

Grey on the plus sign represents energy taken from the grid.
Grey on the minus sign represents energy fed back into the grid.

The amount of "grey" will vary depending on the type of balance (arithmetic vs. vector).

Colors represent consumption minus production. Depending on whether it's a plus or minus, the result is applied to the grey chart in the form of colors - red if you consume more than you produce and green if you produce more than you consume.

Comparing the arithmetic balance to the vector balance, you will notice that the green bars "better" fill the grey background (there is less grey), which means that mathematically, you are making better use of the energy you produce.