If you're referring to the federal solar energy credit, then, in TurboTax Online:
- Open TurboTax Online
- Select Tax Home in the left pane
- On the Hi, let's keep working on your taxes! screen, select the dropdown on the right side of the Deductions & Credits box, then select Start, Continue, or Pick up where you left off
- On the Your tax breaks page, scroll down and open the dropdown next to Your Home. Select Start to the right of Home Energy Credits
- On the Energy-Saving Home Improvements page, select Yes, we made energy-efficient improvements or have a carryforward, then select Continue
From there, you should be able to enter your information. See the Instructions for Form 5695 for guidance.
If this isn't what you're referring to, feel free to post back with more information.