If I consider all of the aspects of the analysis, including the ones the PV caculators omit, the shortest break-even for SFRs that I've seen is ~15 years although shorter is possible.
Meanwhile, the present value in 2024 of a $20k purchase that was made with 2009 dollars is over $29,000. You have to pay $29k in cash today to get the equivalent purchasing power of a $20k investment you made in 2019. $29k in net income, not gross income. Not to mention losing out on the potential proceeds you might otherwise have earned in spending that $20k differently in 2009.
"Adds $10k to the resale price" + accrued savings in electric bills is cool and all, but it doesn't look so great when compared to spending that same $20k in a 2009 investment into Amazon stock. ($4.20 in 08/2009) vs ($161 in 08/2024). $20k into that stock in 2009 would have resulted in a 2024 payout of $700k. That adds a whole lot of opportunity cost to using that money for a solar install.