Net Energy Metering credits are allocated to the home when the solar panels produce excess energy that is sent to the utility's grid. When the home requires energy beyond what the panels are able to produce, the home pulls from the grid and the net energy meter charges the home. If you have more charges than credits, you will owe your utility company additional money at the end of your 12 month billing cycle. This bill is called the "True-up". To avoid a large true-up at the end of the year, it is important that you maintain the same usage that you consumed before installing solar, as system is sized to meet your current needs.