If I bought a solar panel installation in 2023, but had it installed in 2024, but it is installed and working now, can I claim it on for 5695?

You can't claim the credit until the system is up and operational (placed in service), so you can claim it on your 2024 return.

Here's more on the Residential Clean Energy Credit and Homeowner's Guide to Solar Tax Credit. 

In that case, I'll need to file an amended return because I made a mistake, TurboTax did not advise that was the case.

How easy is it to file an amended return with TurboTax?

If you want to make changes or add a document to a tax return that has already been submitted, you should follow these guidelines. 

• You must first wait until the initial return is completely processed. 
• You will have to use the same TurboTax account that you used for the original tax return. 
• Once you begin your amendment, you'll see your original return.  
• The refund calculator will start new at $0 and only reflect the changes in the refund or tax due 
• Only make changes to the areas of your return that need amending. 
• You have three years from the date you filed your return or two years after you paid the tax due (whichever is later) to file an amendment 

Select your product below and follow the instructions. 

Amend TurboTax Online 

Amend TurboTax CD/Download 

When you say "Completely processed" what do you mean by that?

I filed an amended return via TurboTax already as I did not want to incur a penalty from getting money back on an ineligible deduction.  I'd run into that trouble previously and wanted to avoid it happening again.

Were you due a refund prior to amending or did you have to make a payment? Either you needed to wait until you got your original refund or your original payment cleared otherwise it can delay your amendment.

I was originally due a substantial refund.

I don't care about delays at this point.  I simply wish to avoid a penalty.