(NOTE: The information on this page should not be construed as tax advice. We recommend you check with your tax adviser on this credit and tax preparation questions.)
The federal government offers a 30% credit off your system’s purchased cost. This credit is covered under section 25D of the IRS code. The relevant sections are 25D(d)(2), 25D(e)(2), and 25D(d)8. You can find the 5695 tax form on Residential Energy Credits as well as additional information about the credit here. If you are putting solar on a business, you are eligible to take the investment tax credit and may be able to take depreciation on the project as well for additional savings.
The Federal Tax Credit for homeowners is scheduled to lower to 26% in 2020 and 22% in 2021. It is set to expire at the end of 2023.
For more information on all incentives, check out http://www.dsireusa.org. DSIRE is a terrific resource and has links to IRS code and all legislation.