Elon Musk is about to announce a new product that’s not a car. He said so in a mysterious Tweet designed to induce the highest level of nail-biting suspense. But the Elon Musk of two months ago may have told us exactly what we should expect. “We are going to unveil the Tesla home battery, the consumer battery that would be for use in people’s houses or businesses fairly soon,” Musk said during an earnings conference call in February. He said the product unveiling would occur within the next month or two. Here’s his teaser from today, which drove up shares of Tesla 3.5 percent: Tesla is building the world’s biggest battery factory in Nevada — a $5 billion project that Musk says will reduce the price of battery storage by 30 percent. Combining solar panels with backup capacity could allow homeowners to avoid buying electricity from utilities. If the prices come […]