Turbo Tax advised I’ve maxed out my tax credit for my 2019 tax filing. Can I apply the extra credit to apply to my 2020 taxes?

under IRC code sec 25D - yes it's a carryforward that should transfer from your 2019 return when you start 2020 and you are asked if you want to transfer info. 

(c)Carryforward of unused credit
If the credit allowable under subsection (a) exceeds the limitation imposed by section 26(a) for such taxable year reduced by the sum of the credits allowable under this subpart (other than this section), such excess shall be carried to the succeeding taxable year and added to the credit allowable under subsection (a) for such succeeding taxable year.

subsection (a) applies to

a)Allowance of credit

In the case of an individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to the sum of the applicable percentages of—
(1)the qualified solar electric property expenditures,
(2)the qualified solar water heating property expenditures,