Hi,I'm Zoey and I'll be assisting you. I'm reviewing your question now. Please be patient while I research and compose a reply for you.
It's always best not to jump at an unsolicited too good to be true offer from some company you can't verify. Many make calls like this just to scam people. Then once they get your credit card number and other personal information, they can use what they have to commit identity theft.
You are correct. There is no website at guaranteedsolar.com. The domain name has not been registered and is for sale.
The Better Business Bureau is aware of a company named Guaranteed Solar in Colorado. They are also known as Innersol Global. The company is F rated, which is a reason in and of itself not to do business with them. The BBB also has a red alert on the company's review indicating that the address of the company does not check out. Mail to them goes unreturned.
All in all, I'd block this caller. If you're interested in solar energy for your home, contact the Better Business Bureau and see if there are recommended dealers in your area in order to avoid fraud.
Just checking in to see if you need more help or any clarification of my answer. If so, please reply here on this question thread.