Well, nothing ventured, nothing gained. Does it cost anything to post on Craig’s List?
The solar company ad doesn’t say anything about the solar company using the photos. Based on the ad, the photographer could take the photos and not give them to the solar company.
The photographer’s pitch is pretty good. It’s also used frequently, usually to get a discount rather than free work. I can’t count the number of times some salesman has been looking for a discount for a customer because they are trying to get a foot in some door and want to provide a product for less than cost, while claiming they will make it up on future business with that customer. It seldom works that way though.