Solar and wind are intermittent, and sometimes there's a glut. The Zappi helps you make use of that glut.
As distributed energy sources like solar get more popular, many homeowners will have times when they are producing more energy than they can realistically use. Often, they can sell that energy to the grid—but that's much less lucrative or efficient than using it yourself.
But for folks who are already driving an electric or plug-in hybrid car, the first place to look might be your own driveway or garage. Zappi is an electric vehicle charging station that was initially launched through a successful crowdfunding campaign, and is about to go into actual production.
It communicates with both your car and your home to maximize the amount of charge you're getting from on-site solar or wind. In fact, if you tell it to, it will only charge using excess solar or wind—whatever is not being used by your house—at whatever rate it can. That means, on sunny or windy days when you don't have to go anywhere, you can simply ask Zappi to soak up excess production and you'll be driving on free, green energy that you'd otherwise have had to sell.
Zappi is the brainchild of MyEnergi, a company whose explicit mission is to encourage more self-consumption of green energy. Their other main product, the Eddi, pushes excess solar consumption to hot water and/or heating devices.
Here's Robert Llewellyn getting very, very excited about the Zappi...