There is one toy under Susan Scott’s Christmas tree in Longmont, Colo. that does not require batteries.

It’s a silly little green plastic frog, she said. It jumps and moves along like a little robot frog, or at least that’s what it’s supposed to do. She hasn’t tested it out. It came in the mail, and she wrapped it up in red paper and a gold ribbon. It’s for her six-year-old son.

The little frog is one of countless solar-powered gadgets stuffing stockings this year.

Online retailers like Maninthebox.com and Amazon.com have listed solar gadgets in their own category, indicating the popularity of the trend.

While tax incentives and rebates have made major solar projects and home solar installations popular around the country and around the world, small-scale inventions have made solar a popular technology at home and a trendy gift idea.

Both Logitech and AU Optronics released solar-powered keyboards this year. Nerd hikers have been spotted with solar-powered backpacks to give life to their iPods and laptops even on long backcountry trips.

Among Maninthebox.com’s solar gadgets are solar iPhone battery chargers for $9.99, LED solar powered keychain flashlight for $1.69 and a goofy solar cockroach for just a few bucks.

Scott found her solar frog online and felt like it would be a fun toy and an educational gift for her son.

“It’s a junky little toy, but it’s so cool,” she said. “The solar is what makes it cool.”

She hopes to teach her son a little about how solar power works with the frog.

She and her husband hope to install solar panels on their home within the next few years and she’s been researching the technology. While major home installations aren’t in the budget, a solar frog is a fun experiment.

“I think it could probably teach me a bit about the technology, too,” she said.

Online retailers are also selling solar education kits this year, which allow kids and parents to assemble different solar-powered toys and see how the connections and power work.

Reviewers on Amazon.com are actually lauding the goofy solar toys like Scott’s frog, a “frightened grasshopper,” and the cockroach as educational gifts.

One woman said she used the grasshopper to teach home school children about solar cells.

“It’s a great tool,” the review writes. “My kids loved making a shadow over him to make him stop wriggling.”

Pictured: Elenco's Happy Hopping Solar Frog, an interactive toy that requires children to assemble it before they can play with it, forcing them to learn about solar when all they really want is to watch TV.