Here's a quick video showing the meters in our meter box and the one on the right is moving backwards. We have 3 phase power, and as such 3 meters. The solar panels are connected to the meter on the right and the house uses the power from the solar panels first, and then pushes any excess power from the solar panels onto the grid. This is called net metering, when the excess power gets pushed onto the grid. Different parts of our home use power from the 3 meters. When the meter on the right is moving faster than the meters on the left, then we are generating more energy than we need, from the solar panels, and the excess is being fed back onto the grid. This is generally the case during the day, pushing excess power onto the grid. Then at night we would draw all the power from the grid, when the solar panels do not generate energy.