How do I enter my credit amount for a solar energy credit on SC1040TC?

To claim the credit :

1. Open or continue your return, if you don't already have it open.
2. In TurboTax, search for Energy improvements. 
3. Click the Jump to link in the search results.
4. At the bottom of the Energy-Saving Home Improvements screen, answer Yes and continue. Follow the instructions.

To be eligible for the credit:

•  Your solar PV system was ‘placed in service’ between January 1, 2006, and December 31, 2021.
• The solar PV system is located at a residential location in the U.S. (but not necessarily your primary residence).
• You own the solar PV system ( e.g., you purchased it with cash or through financing)
• The solar PV system is new or being used for the first time. 

Also, the solar credit is a non refundable credit. A non-refundable tax credit can only reduce a taxpayer's liability to zero. It can't be used to increase your tax refund or to create a tax refund when you wouldn't have already had one.

I understand that. My question is more that last year when I filed my state taxes for SC, they were rejected because form SC1040TC was not supported by Turbo Tax electronically so I had to print my tax return out and mail it in with the form included which substantially slowed down my tax return. Is form SC1040TC electronically supported this year so my return does not again get rejected and have to be mailed in? Which then defeats the purpose of my paying for Turbo Tax to e-file and get my return much quicker. 

Yes, Form SC1040TC, Tax Credits, is available in TurboTax for electronic filing.  

Please see the TurboTax Help article State forms availability table for TurboTax individual (personal) tax products for more information.

Note that, according to Form SC1040TC, found at Individual Income Tax - Forms, 

For taxpayers installing a solar energy system, small hydropower system, or geothermal machinery and equipment in a South Carolina facility. This credit is limited to the lesser of $3,500 per facility or 50% of your tax liability.

Great, thank you!