Opinion:

The problem with door-to-door sales is they are commission sales and since they work on commission, it is in their interest to convenience you that you need more than you need, if not everything, because they make more the more you buy into whatever they're selling.

Additionally, times have changed and the person going door-to-door can just as easily be a scammer trying to collect your information or even try to case your home for theft, which is why it is important not to let anyone in who is going door-to-door. It is always a good idea to call your local police department, using the non-emergency line, to verify if anyone has checked in with the town to go around door-to-door (a requirement for most communities).

Lastly, as someone else said, if it sounds too good to be true, it likely is. Solar equipment is not cheap. It is partly why the government has offered a lot of tax rebates and incentives to encourage people to switch to solar (to help offset the cost).

If you ever do consider getting solar, please remember it is best to buy your equipment and not lease it. While the upfront cost may be greater, you will not be paying monthly or annual fees indefinitely. For many, the whole point of switching to solar is to either lower or, if possible, outright remove their electric bill, not add a new long-term bill. And lastly, many homeowner insurance policies will not cover your roof or solar equipment, if you lease. That means if something is installed wrong, or even some natural weather issue takes place, you're still out of pocket for all the repairs, replacements, and labor if you lease.

That all said, whatever your choice, it is best that you call a company of your choosing, and not the random person who happens to knock on your door. You will nearly always do better shopping around and doing your own homework.