Tesla Motors says it's unveiling a new product next month; not a car, but likely a battery

Tesla Motors says it will reveal a new product next month, but it's not a car.

CEO Elon Musk tweeted Monday that "a major new Tesla product line" will be revealed April 30.

Tesla shares rose 3 percent to $190.60 after the tweet.

Musk said in February that the company would soon unveil a home battery that would be ready to go into production in about six months.

Tesla has already partnered with Solar City — a solar energy company chaired by Musk — on battery storage systems for businesses that charge up during peak sunlight hours and use the energy in the evening, when demand spikes and rates rise.

Solar City has also installed Tesla battery storage systems in about 300 California homes as part of a pilot program.