It may pay to review IRS form 5695 to fully answer your question or take the question to your favorite CPA; which I am not.
My reading of the form indicates 30% of the cost of the solar installation can be deducted from your tax obligation for the year of the installation. I saw nothing that indicated battery charging was involved nor would the credit be valid for succeeding years. If the credit is greater than the amount of tax owed the balance can be carried over to 2016.
There may be a limit of $500 for all such Residential Energy credits since 2005 or so.