Specialist Installer of Solar Photovoltaic and Battery Storage Systems in Oxford and Surrounding Counties

Call us on: 07717 004240

or email enquiries@simssolar.co.uk

Tesla PowerWall - Why am I still exporting electricity?

The Tesla PowerWall battery management system is very sophisticated and this is one of the reasons why Tesla are able to offer such a strong product warranty. The battery management system is there to protect the battery from damage, part of that protection involves ensuring there is sufficient charging current during the charging cylce and prevention of excessive charge cycling at elevated levels of battery state of charge.

For that reason, when there are only a few hundred watts of excess power from the solar PV system this will be exported to the grid rather than be stored and secondly, when the battery state of charge exceeds 85%, charging of the battery will not take place. The state of charge is required to reduce below 85% for charging to resume.

You may also notice that the battery appears not to discharged fully, with perhaps 6-7% of residual storage available. This is also part of the battery management system.

Key Term: Tesla, PowerWall, efficiency, optimisation