CenterPoint provides the connection from generators to customers but does not bill customers directly. If you have enrolled in a buy-back program with your Retail Electric Providers (REP), then your bill is based on usage, excess generation, and rate charge/rate credit. For more information about this, contact your REP.
If you feel that the utility meter is reporting values incorrectly, you can contact your REP and request a meter accuracy test. If your REP advises you to contact CenterPoint, you can call CenterPoint's customer service number 713-207-2222 and request a meter calibration verification. There may be a fee assessed for this test.