Reuse of Electric Vehicle Batteries for Solar Energy Storage

Repurposing used EV batteries as energy storage for PV systems.


Tech Partner

RePurpose Energy, Inc.


Fairfield, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Projects Updates/The Results

This agreement was formally executed on October 15, 2020, and held its kick-off meeting on November 3, 2020.

The Issue

Repurposing used EV batteries as energy storage for PV systems represents an opportunity to divert waste batteries from disposal and significantly reduce the pending impact on recycling facilities throughout California. Unfortunately, a lack of data on second life battery degradation, performance, and cost have delayed the commercialization of this application. Without validated data, financiers and insurers are unable to effectively calculate risk to fund and insure these projects. As a result, used EV batteries are ending up in the waste stream while new lithium-ion batteries are produced for new stationary energy storage systems.

Project Innovation

RePurpose Energy is conducting a series of laboratory-based cycling tests to identify the degradation rate and effective useful life of individual used EV battery cells based on a variety of control strategies. The team is creating a scale model of a second life EV storage system connected to a grid emulator to validate the optimal control strategy for a solar PV and energy storage system. Finally, the team is taking the learnings from the laboratory testing and deploying a full-scale demonstration installation to collect data on actual system performance. The demonstration site showcases resiliency and cost benefits to the identified business and local economy.

Project Goals

Validate ability of second-life batteries to provide resiliency benefits.
Provide a cost comparison of second life EV batteries to equivalent first use lithium-ion batteries for energy storage.
Characterize the degradation rate of second-life batteries over their lifetime through labscale accelerated cycling tests

Project Benefits

The continued adoption of electric vehicles will generate waves of lithium-ion battery waste, which is difficult and expensive to recycle. This project will facilitate diversion of battery waste and deferment of recycling costs by giving EV batteries a second life. One of the main barriers to second-life energy storage systems is the need for extensive cell testing and characterization. This traditionally requires a great deal of testing time and expense, resulting in erosion of the cost advantage of the used batteries. This project will result in a methodology to quickly and accurately estimate the remaining useful cycle life of a retired EV battery cell in a stationary energy storage system. This project will demonstrate a second-life energy storage system consisting of full EV battery packs without disassembly to reduce the time and cost of repurposing EV batteries.

Lower Costs

Lower Costs

The solar PV and batteries will reduce energy costs via on-site generation and time of use arbitrage, demand charges via peak load reduction and shifting, and greenhouse gas emissions via reduction in on-peak energy demand. The b

Economic Development

Economic Development

The team will subcontract with a local solar installer to deploy the onsite renewable generation and energy storage, thus spurring economic development in a low-income community.

Environmental & Public Health

Environmental & Public Health

The site will achieve greenhouse gas reductions via installation of rooftop solar PV and second-life EV batteries. RePurpose estimates that the solar + storage microgrid will reduce the site's carbon footprint by about 62,000 kg/

Greater Reliability

Greater Reliability

This project aims to deliver greater electricity reliability to the host site and its local community by providing backup power in the event of an unplanned outage or public safety power shutoff (PSPS). In 2019, many PG&E custome

Key Project Members

Benjamin Lyon

Benjamin Lyon

Chief Revenue Officer

Contact the Team