If you were interested in solar, you wouldn’t choose it based on some door knocker sales people. Due diligence re your state’s position is probably easy enough to do on the internet. If you are in a position to pay outright for something like this, you probably would already know it. Would you buy anything from a door to door salesman?
Nowadays up front paid up installation is getting very affordable. you just need to do the ROI. Is your house older? How is your roof? Is your weather really solar compatible?