The American Recovery and Reinvestment Act of 2009 created a 30% tax credit for the purchase & installation of residential solar water heating systems installed between January 1st, 2009 & December 31st, 2016.
To qualify for the tax credit, the customer will need their receipt of the cost of the product (including installation), the date is was placed in service, & the manufacturers certification statement which is available below. The tax credit is a direct debit of a taxpayers total tax liability.
Manufacturer’s certification statement [PDF]