Joshua Zimmerman isn’t a full-time inventor, but that’s about to change.

The 30-year-old middle school science teacher has raised almost $100,000 on Kickstarter project, the "Folding USB Solar Cell." With 15 days left, the Milwaukee amateur inventor has well surpassed his $5,000 goal to build an inexpensive, easy-to-use, practical, every-day solar USB charging system.

As his Kickstarter description explains, the tool is for those of us not just preparing for the end of the world.

"I’ve been tinkering around the last two and half years as a hobby," says Zimmerman, who recently moved from his parents basement into a small West Side office.

Zimmermann calls himself an "enthusiastic hobbyist who has found a niche market."

The inventor approaches these projects from a middle-school science teacher perspective. "When I started, I found ‘step A’ and ‘step Z,’ with no projects in the middle," he says. So Zimmerman filled in the blanks with inexpensive, simple projects he could teach to his class.

Before the Kickstarter project, Zimmerman had been selling Altoid tins turned into USB phone chargers through his company called Brown Dog Gadgets. "These are the things keeping the lights on in Tosa," he says.

But the logical next step from these battery-powered chargers was solar. Zimmerman searched online for a charger his students could make, and he found one. "If you can solder two wires together, you could make this," he says.

Zimmerman continued making bigger and better prototypes until he built something that was too complicated and expensive for his students and customers on his Web site. It was also taking too much of his time.

"I realized I can’t make this thing myself," says Zimmerman.

So Zimmerman found a Chinese manufacturer to mass produce a fold-out group of solar cells that attaches to a USB plug. His slim solar panels, that look like an iPad case when folded, will charge an iPhone, for example, in 2-3 hours, depending on the amperage of the model (five or seven watt).

However, Zimmerman didn’t have the resources to bring his product to mass market, so he turned to Kickstarter, the crowdsourcing business incubator. "I thought I’d give it a shot."

That shot is paying off quickly. In five hours he met his initial goal. As of press time, nearly 900 different backers have donated.

Says Zimmerman, "I’m just going to see how high it will go."

The Kickstarter charger only works with natural light, of course. It sports just one LED light to indicate that sunlight is hitting the device, but it won’t overcharge. Zimmerman suggests pairing the charger with a portable USB battery so you can charge the external battery by day and hook it up to your phone or laptop or gadget by night.

The 5-watt folding solar cell charger will sell $55. Zimmerman will sell the 7-watt model for $70.

"Honestly, it’s electronics basics," says Zimmerman. "Everyone thinks that solar is this magical, mystical thing, but Edison was dealing with solar power."

And it looks like Zimmerman won’t be returning to his teaching job next fall.

"It’s very exciting, for someone who was just doing this as a hobby. Chicago has a very big technology entrepreneur thing going on right now," says Zimmerman. "Milwaukee, there are a few things popping up. My hope is that guys and gals get things going up here. Milwaukee used to be a big industrial area at one point, and it would be nice to see us going back there again."