The unnamed narrator was relaxing at home while his wife Debbie prepared supper in the kitchen when the doorbell rang. He answered it and found Eric, a sales representative from Superior Solar, waiting with a pitch for a new solar system. The existing system came with the house so the narrator invited Eric in to discuss his company's products.
However, things aren't what they seem and the story takes a punny twist.
Turtledove got the idea when a salesman offered him "solar systems" meaning solar power systems. His daughter Rebecca pointed out the obvious pun, and Turtledove gave her royalties for the resulting story.