Tax credits for renewables

Hello financial experts.  I'm investing in renewables despite any credits or tax refunds.  But I figure I should know if I'm going to get any.  Without trying to give away too much of my personal finances...

I don't have any W2 income (paycheck) but I do have investment dividend income.  My income taxes are relatively low since my lifestyle is relatively simple.

I bought a plug in prius this year.  From what I can tell, it will generate about a $4,000 tax credit.  I believe that is a non-refundable tax credit.  So it will cut my taxes this year and the most it can reduce them is to 0 (no check from the IRS).  I also believe this can't be rolled over to next year's taxes.    Does anyone know if I have that all correct?

I'm beginning to plan out a solar electric system for the house.  If I do it next year, there's a 30% tax credit from the feds.  From what little I've found, that is also a non-refundable credit (lowest my taxes can go is $0) but it sounds like it can be rolled over to ensuing years.  Does anyone know if I have that correct?  Is there a limit regarding how long I can roll it over?

Thanks for your help/input!

If I recall that 30% federal credit is starting to go down beginning after next year, so 2019 is the last year it's 30%, and after a couple years will end. It's a credit towards your tax bill, rather than a deduction, and I think you can roll over excess if you can't take it all at once. The IRS site has the rules laid out for it on their web site including income limits if any.