This is a hard question to answer!!!
Average is 13 years in MN, and most will see payback period between 10 and 16 years -
https://www.ecowatch.com/solar/worth-it/mn5-15 years in most of the US -
https://www.solarreviews.com/blog/how-to-calculate-your-solar-payback-periodWhy is it so hard to figure out? Here are some things to consider:
The roof size and size of system
The roof size matters because everyone has a different roof. The bigger your roof, the bigger the system you could install. Bigger system makes more power, but is more expensive
The electricity bill because you could have a small system and save money. And if we use lots of electricity we need a bigger system.