You cannot claim a solar energy credit for the purchase of batteries alone. The credit is for the purchase of an entire system, and the installation of the system must be completed during the tax year.
https://www.energy.gov/eere/solar/homeowners-guide-federal-tax-credit-solar-photovoltaics
@TomD8 wrote:
You cannot claim a solar energy credit for the purchase of batteries alone. The credit is for the purchase of an entire system, and the installation of the system must be completed during the tax year.
https://www.energy.gov/eere/solar/homeowners-guide-federal-tax-credit-solar-photovoltaics
The revision to section 25D contained in the Inflation Reduction Act added a new credit for storage batteries, as long as the capacity was at least 3kWh.
As far as I can tell, you can't claim a credit to repair or replace an existing, old or out of date system. But if you are adding new equipment (a new solar system, new additional battery capacity), those additions will qualify when you perform the work, even though you have already claimed a credit for the first system.