These tax incentives are claimable by anyone who signs up for solar when they file there 2021 income taxs.
The current Federal tax credit is 26% for the rest of this year. However starting next year and going forward this tax credit will get lower and lower. In order to get the current tax you need to have your system installed and running before the end of the year.
This credit is a dollar for dollar reduction in the income taxes for you when you claim it worth 26% of the basis invested. This money can be reinvested into your solar system to lower the principal cost of your system.