Second-Hand Tesla Battery for Grid Connected Energy Storage


Grid-connected lithium batteries are an essential part of a power system dominated by sustainable energy sources for buffering, grid stability and frequency control. In the future grid, where renewable energy like wind and solar are dominant, the need for optimisation between production and consumption is key. Flexibility and resilience via the use of batteries are important and it is also a commercially interesting area. However, batteries are very costly so the opportunity to source batteries from EVs is interesting from a commercial point of view but also from a climate perspective. Prolonging EV battery life is important to improve the LCA footprint of EVs in general. EV batteries from damaged cars could be used for purposes where the lifetime can be extended way beyond what is possible and realistic in an EV. Second-life batteries should be used for this purpose thus contributing to the purposes described above for grid stabilization, peak shaving etc. and should in such use be able to stay in production for many years and provide an attractive alternative to using new batteries for this purpose.


This project has the goal of taking batteries from damaged Tesla vehicles, implementing the needed control software and user interface to bring the batteries online on the grid and provide the services as described above. Battery management, control software, and interfaces will take advantage of existing solutions from the hardware vendors and enable integration with the smallest possible footprint. Control software must be able to optimize the charging and discharging of the battery with respect to the fluctuating power prices and take into consideration the production from the photovoltaic (PV and consumption in the installation).

The project intends to take several 5.3 kWh modules from Tesla vehicles and equip them with commercially available AC/DC inverters and make them ready for domestic applications. The newly repurposed battery will therefore be tested to provide several behind-the-meter services like peak consumption reduction or self-consumption via PV plants. Energy arbitrage services, such as charging when electricity is cheap and using it to cover local consumption during peak hours will also be tested.


The project aims to mature the technology. At the start of the project TRL is 5 (the battery is already operational and control approaches are already tested in the laboratories of DTU). At the end of the project, TRL will be 7 (system tested and operational in a dedicated environment). This will provide a better base for further activities, e.g. regarding market implementation and grid services.


4-leaf Consulting



Financed by


Start: November 1st 2023

Completion: October 31th 2024

Total budget: DKK 1,549,815

Contact person

Marie Vedel Lauridsen

Marie Vedel Lauridsen
Project Manager
Tlf: +45 2265 4600